Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. YES ☑ NO ☐

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. YES ☐ NO ☑

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. YES ☐☑ NO ☑☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). YES ☑ NO ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer”, “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☑

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). YES ☐ NO ☑

The aggregate market value of the voting and non-voting common equity held by non-affiliates of the registrant, based upon the closing price of a share of the registrant’s common stock on June 30, ~~2019~~2020 as reported by the ~~NASDAQ~~Nasdaq Global Select Market on that date, was approximately ~~$6,612~~$6,293 million. This calculation does not reflect a determination that certain persons are affiliates of the registrant for any other purpose.

The number of shares outstanding of the registrant’s common stock as of February ~~7, 2020~~5, 2021 was ~~57,003,654~~57,394,377 shares.

Portions of the registrant’s Proxy Statement for its ~~2020~~2021 Annual Meeting of Stockholders (the “Proxy Statement”), to be filed with the Securities and Exchange Commission, are incorporated by reference into Part III of this Annual Report on Form 10-K where indicated. The Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the registrant’s fiscal year ended December 31, ~~2019.~~2020.

This Annual Report on Form 10-K contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this Annual Report on Form 10-K other than statements of historical fact, including statements regarding our future results of operations and financial position, our business strategy and plans, and our objectives for future operations, are forward-looking statements. The words “believe,” “may,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “expect,” and similar expressions are intended to identify forward-looking statements. We have based these forward-looking statements largely on our current expectations and projections about future events and trends that we believe may affect our financial condition, results of operations, business strategy, short-term and long-term business operations and objectives, and financial needs. These forward-looking statements are subject to a number of risks, uncertainties and assumptions, including those described in Part I, Item 1A, “Risk Factors” in this Annual Report on Form 10-K. Moreover, we operate in a very competitive and rapidly changing environment. New risks emerge from time to time. It is not possible for our management to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we may make. In light of these risks, uncertainties and assumptions, the future events and trends discussed in this Annual Report on Form 10-K may not occur and actual results could differ materially and adversely from those anticipated or implied in the forward-looking statements. We undertake no obligation to revise or publicly release the results of any revision to these forward-looking statements, except as required by law. Given these risks and uncertainties, readers are cautioned not to place undue reliance on such forward-looking statements.

Unless expressly indicated or the context requires otherwise, the terms “Proofpoint,” “Company,” “Registrant,” “we,” “us,” and “our” mean Proofpoint, Inc. and its subsidiaries unless the context indicates otherwise.

Proofpoint is a leading next-generation cybersecurity company that enables primarily large and mid-sized organizations worldwide to protect the way their people work from advanced threats and compliance risks. Our integrated suite of products works together to help organizations build people-centric security and compliance programs. We provide threat protection, information protection, user protection, business ecosystem protection, and compliance solutions to address today’s rapidly changing threat and compliance landscape. Our solutions are built on a flexible, cloud-based platform and leverage proprietary technologies - including big data analytics, machine learning, deep content inspection, secure storage, advanced encryption, intelligent message routing, dynamic malware analysis, threat correlation, and virtual execution environments.

Every company’s greatest asset and greatest security risk is its people. Cyberattacks have fundamentally shifted from targeting infrastructure to targeting people, relying on tricking users into running code, divulging their passwords, or even sending money or data. This transformation of the threat landscape manifests in nearly every form of cyber threat, from nation state advanced persistent threat ~~(APT)~~(“APT”) actors relying on phishing, through to cybercriminals launching massive ransomware email campaigns, and more targeted campaigns designed to steal valuable data from both legacy and cloud-based systems. At the same time, the rapid adoption of cloud applications has increased organizations’ attack surface by moving both threats and sensitive data away from the traditional network perimeter, reducing the effectiveness of many existing security products. These factors have contributed to an increasing number of severe data breaches and expanding regulatory mandates, notably the European Union’s General Data Protection Regulation ~~(GDPR)~~(“GDPR”), all of which have accelerated demand for effective threat protection and compliance solutions.

Our platform addresses this growing challenge by not only protecting data as it flows into and out of the enterprise via on-premises and cloud-based email, social media, and other cloud applications, but also by keeping track of this information as it is modified and distributed throughout the enterprise for compliance and data loss prevention, and securely archiving these communications for compliance and discovery. We help organizations reduce their critical risk in five major ways:

Our platform and its associated solutions are sold to customers on a subscription basis and can be deployed through our unique cloud-based architecture that leverages both our global data centers as well as optional points-of-presence behind our customers’ firewalls. Our flexible deployment model enables us to deliver superior security and compliance while maintaining the favorable economics afforded by cloud computing, creating a competitive advantage for us over legacy on-premises and cloud-only offerings.

We were founded in 2002 to provide a unified solution to help enterprises address their growing data security requirements. Our first solution was commercially released in 2003 to combat the burgeoning problem of spam and viruses and their impact on corporate email systems. To address the evolving threat landscape and the adoption of communication and collaboration systems beyond corporate email and networks, we have broadened our solutions to defend against a wide range of threats, including email, mobile apps and social media, to protect the information people create from both compromise and compliance risks, and to archive and govern corporate information. ~~Today, our solutions are used worldwide to protect well over 100 million end users at enterprise customers, and millions more via service providers through our Cloudmark division.~~ We market and sell our solutions worldwide both directly through our sales teams and indirectly through a hybrid model where our sales organization actively assists our network of distributors and resellers. We also distribute our solutions through strategic partners.

Our integrated suite of on-demand security-as-a-service solutions enables large and mid-sized organizations to protect people throughout the enterprise from advanced attacks and compliance risks. Our comprehensive platform provides a secure email gateway, advanced threat protection, security awareness training, threat intelligence, email authentication, email encryption, data loss prevention, digital risk protection, cloud application protection, web browser isolation, archiving, e-discovery, and threat response capabilities. These solutions are built on a cloud-based architecture, protecting enterprises and their customers from inbound threats via email, social media, and mobile apps, while identifying and protecting enterprise data not only where it is stored within the enterprise but also as it transits beyond the organization’s borders such as via email or social media. We have pioneered the use of innovative technologies to deliver better ease-of-use, greater protection against the latest advanced threats, and lower total cost of ownership than traditional alternatives. The key elements of our solution include:

We provide a multi-tiered security-as-a-service platform consisting of solutions, platform technologies and infrastructure. Our platform currently includes product families and related bundles for the convenience of our customers, distributors and resellers. Each of these solutions is built as an aspect of our security-as-a-service platform, which includes both platform services and enabling technologies for both security and compliance. Our platform services provide the key functionality to enable our various solutions while our enabling technologies work in conjunction with our platform services to enable the efficient construction, scaling and maintenance of our customer-facing solutions.

Our suite is delivered by a cloud infrastructure and can be deployed as a secure cloud-only solution, or as a hybrid solution with optional physical or virtual points-of-presence behind our customers’ firewalls for those who prefer to deploy certain functionality inside their security perimeter. In all deployment scenarios, our cloud-based architecture enables us to leverage the benefits of the cloud to cost-effectively deliver superior security and compliance while maintaining the flexibility to optimize deployments for customers’ unique environments. The modularity of our solutions enables our existing customers to implement additional modules in a simple and efficient manner.

Proofpoint Threat Protection products leverage a broad set of detection techniques that are constantly refined as the threat landscape evolves. The products detect and prevent threats across email, web, networks, and cloud applications, and deliver rich intelligence to enable enterprises to understand as much as possible about the attacks they are seeing and the adversaries behind them.

A comprehensive data protection strategy must address both security and compliance risks. Our enterprise data loss prevention, encryption insider threat management and compliance solutions defend against leaks of confidential information, and helps ensure compliance with common U.S., international and industry-specific data protection regulations - including the Health Care Insurance Portability and Accountability Act of 1996 (“HIPAA”), the Gramm-Leach-Bliley Act, Canada’s Personal Information Protection and Electronic Documents Act, as well as acts such as CA SB 24, MA 201 CMR 17.00, ITAR, NERC-CIP, CFTC red flag rules, Basel II, EuroSOX ~~(Directive~~(“Directive 84/253/~~EEC)~~EEC”), the European Union GDPR, and the Payment Card Industry Data Security Standard ~~(PCI-DSS)~~(“PCI-DSS”).

Proofpoint User Protection combines simulation, assessments, education, reinforcement, and measurement to provide the ideal foundation for your security awareness and training program, utilizing hundreds of different phishing templates across dozens of languages and categories to simulate attacks and evaluate end users on various threats, including malicious attachments, embedded links, and requests for personal data. Users who are deceived by simulated attacks receive “just-in-time teaching” and administrators receive real-time reporting to focus awareness efforts and track progress.

Proofpoint Business Ecosystem Protection looks beyond the enterprise perimeter to deliver real-time, omnichannel digital risk discovery and protection from email fraud, brand fraud, data loss, physical threats, and cyber threats. With this solution, enterprises can engage with their customers across web, email, mobile, and social media with the confidence that their brands and customers are safe from all forms of digital risk.

Key capabilities within Proofpoint Business Ecosystem Protection products include:

Proofpoint Compliance Solutions are designed to ensure accurate enforcement of data governance, data retention and supervision policies and mandates; cost-effective litigation support through efficient discovery; and active legal-hold management. It can store, govern and discover a wide range of data including email, instant message conversations, social media interactions, and other files throughout the enterprise. With this solution, enterprises can engage with their customers across web, email, mobile, and social media with the confidence that their brands and customers are safe from all forms of digital risk.

Our platform services provide the key functionality to implement our various solutions, using our enabling technologies. Our platform services primarily consist of:

Our enabling technologies are a proprietary set of building blocks that work in conjunction with our application services to enable the efficient construction, scaling and maintenance of our customer-facing solutions. These technologies primarily consist of:

We deliver our security-as-a-service solutions through our cloud architecture and international data center infrastructure. We operate thousands of physical and virtual servers across ~~sixteen~~fifteen data centers located in the United States, Canada, the Netherlands, France, Germany, and Australia.

Our cloud architecture is optimized to meet the unique demands of delivering real-time security-as-a-service to global enterprises. Key design elements include:

As of December 31, ~~2019,~~2020, we had customers of all sizes across a wide variety of industries. A number of our largest customers use our platform to protect more than a million users and handle over a billion messages per day. During the year ended December 31, 2020, two partners accounted for 13% and 11%, respectively, of total revenue. During the year ended December 31, 2019, two partners accounted for 12% and 11%, respectively, of total ~~revenue in each year.~~revenue. During the ~~years~~year ended December 31, 2018, ~~and 2017,~~ one partner accounted for 12% of total ~~revenue, respectively.~~revenue. These partners sold to a number of end users, none of which accounted for more than 10% of our total revenue in 2020, 2019 ~~2018~~ and ~~2017.~~2018. In each year since the launch of our first solution in 2003, we have maintained a renewal rate with our existing customers of ~~over~~ 90%. or higher.

We ~~target large~~had approximately 8,000 enterprise customers as of December 31, 2020, which consists of customers that generate more than $10,000 in annual recurring revenue, an increase of 13% as compared to December 31, 2019. Our enterprise customers included approximately 57% of the Fortune 1000 companies and mid-sized organizations across all major verticals including aerospace and defense, education, financial services, government, healthcare, manufacturing and retail. We have been particularly successful selling to27% of the ~~largest enterprises in the United States as ranked by Fortune Magazine. We have also had success penetrating the market leaders in a number of significant verticals including:~~Global 2000 companies.

We primarily target large and mid-sized organizations across all industries. Our sales and marketing programs are organized by geographic regions, including Asia-Pacific, EMEA, Japan, North America, and South America, and we further segment and organize our sales force into teams that focus on large enterprises (4,000 employees and above), mid-sized organizations (1,000 - 4,000 employees) and existing customers. In addition, we create integrated sales and marketing programs targeting specific vertical-markets. This vertical-market approach enables us to provide a higher level of service and understanding of our customers’ unique needs, including the industry-specific business and regulatory requirements in industries such as healthcare, financial services, retail and education.

We sell through both direct and indirect channels, including technology and channel partners:

For sales involving a partner such as a distributor, reseller or strategic partner, the partner engages with the prospective customer directly and involves our sales team as needed to assist in developing and closing an order. At the conclusion of a successful sales cycle, we sell the associated subscription, hardware and services to the partner who in turn resells these items to the customer, with the partner earning a margin based on the amount paid to Proofpoint as compared to the amount charged to the customer. With the order completed, we provide these customers with direct access to our security-as-a-service platform and other associated services, enabling us to establish a direct relationship and provide them with support as part of ensuring that the customer has a good experience with our platform. At the end of the contract term, the partner engages with the customer to execute a renewal order, with our team providing assistance as required.

We have a number of marketing initiatives to build awareness about our solutions and encourage customer adoption of our solutions. Our marketing programs include a variety of digital marketing, advertising, conferences, events, white-papers, public relations activities and web-based seminar campaigns targeted at key decision makers within our prospective customers.

We offer free trials, competitive evaluations, and free security and compliance risk assessments to allow prospective customers to experience the quality of our solutions, to learn in detail about the features and functionality of our suite, and to quantify the potential benefits of our solutions.

We believe that our customer service and support provide a competitive advantage and are critical to retaining and expanding our customer base. We conduct regular third-party surveys to measure customer loyalty and satisfaction with our solutions.

We deliver 24x7x365 customer support from support centers located in North America, EMEA and Asia-Pacific regions. We offer a wide range of support offerings with varying levels of access to our support resources.

With our security-as-a-service model, our solutions are designed to be implemented, configured, and operated without the need for any training or professional services. For those customers that would like to develop deeper expertise in the use of our solutions or would like some assistance with complex configurations or the importing of data, we offer various training and professional services. Many implementation services can be completed in one day and are primarily provided remotely using web-based conferencing tools. If requested, our professional services organization also provides additional assistance with data importing, design, implementation, customization, or advanced reporting. We also offer a learning center for both in-person and online training and certification.

We devote significant resources to improve and enhance our existing security solutions and maintain the effectiveness of our platform, monitoring the threat landscape in real-time and making constant adjustments to remain effective as the threat landscape shifts. We also work closely with our customers to gain valuable insights into their threat environments and security management practices to assist us in designing new solutions and features that extend the data protection, archiving and governance capabilities of our platform. Our technical staff monitors and tests our software on a regular basis, and we maintain a regular release process to update and enhance our existing solutions. Leveraging our on-demand platform model, we can deploy real-time upgrades with no downtime.

Our markets are highly competitive, fragmented and subject to rapid changes in technology. We compete primarily with companies that offer a broad array of data protection and governance solutions. Providers of data protection solutions generally have product offerings that include threat protection, virus protection, data loss prevention, flexible remediation, data encryption, and in some cases secure file transfer. Providers of archiving solutions generally have product offerings that provide data storage, search, policy enforcement, legal-hold management, and in some cases supervision.

Certain of our competitors have greater sales, marketing and financial resources, more extensive geographic presence and greater name recognition than we do. We may face future competition in our markets from other large, established companies, as well as from emerging companies. In addition, we expect that there is likely to be continued consolidation in our industry that could lead to increased price competition and other forms of competition.

We rely on a combination of trade secrets, patents, copyrights and trademarks, as well as contractual protections, to establish and protect our intellectual property rights and protect our proprietary technology. As of December 31, ~~2019,~~2020, we had ~~160~~198 patents and 5591 patent applications. We have a number of registered and unregistered trademarks. We require our employees, consultants and other third parties to enter into confidentiality and proprietary rights agreements and control access to software, documentation and other

proprietary information. Although we rely on intellectual property rights, including trade secrets, patents, copyrights and trademarks, as well as contractual protections to establish and protect our proprietary rights, we believe that factors such as the technological and creative skills of our personnel, creation of new modules, features and functionality, and frequent enhancements to our solutions are more essential to establishing and maintaining our technology leadership position.

Despite our efforts to protect our proprietary technology and our intellectual property rights, unauthorized parties may attempt to copy or obtain and use our technology to develop products with the same functionality as our solution. Policing unauthorized use of our technology and intellectual property rights is difficult.

We expect that software and other solutions in our industry may be subject to third-party infringement claims as the number of competitors grows and the functionality of products in different industry segments overlaps. Any of these third parties might make a claim of infringement against us at any time.

People are at the core of our values and our people-centric cybersecurity strategy. As of December 31, ~~2019,~~2020, the Company employed 3,658 people worldwide, of which approximately 70% were employed in the United States with the remaining 30% outside of the United States. None of our U.S. employees are represented by unions. However, there are employees outside of the United States that are represented by works councils in France and Germany.

The Company’s security and compliance products and services are created and supported through a global workforce passionate about the Company’s culture and cybersecurity vision. Our people-centric approach to cybersecurity is uniquely adept at protecting our customers’ greatest assets, their people, while addressing their greatest risks, their people. At Proofpoint, our people - and the diversity of their lived experiences and backgrounds, thinking and perspectives, and work skills and experiences - are the driving force behind much of our success. We encourage and value innovation at every level of our workforce. Our people include leaders across technical fields covering threat research, machine learning, analytics and cybersecurity engineering, to customer success, technical support, operations and information security. Our people, whether they are in sales, marketing, or general administrative functions, strive to understand the challenges and unique needs of our constituents and deliver predictable and efficient results.

Our Senior Vice-President, Human Resources (“SVPHR”), who reports directly to our Chief Executive Officer (“CEO”), leads the development and implementation of the Company’s human capital strategy, including the attraction, acquisition, development and engagement of talent; however, it is the responsibility of all of Proofpoint, its management and its employees, to execute and build a collaborative and engaging workplace where all employees have an opportunity to do their best work and where we ~~had 3,368 employees.~~act as a team to solve our customers’ most challenging security issues.

Our SVPHR, with our CEO and executive management team, are responsible for developing the Company’s diversity and inclusion vision and roadmap and integrating these into the Company’s culture and operations. The roadmap includes framing the Company's global policies and programs for leadership and talent development, compensation, benefits, staffing and workforce planning, human resources systems, education and organization development, workplace strategies, and global sourcing and indirect procurement, and ensuring effective and efficient internal company operations.

The CEO and SVPHR in concert regularly update our board of directors and the Compensation Committee on human capital matters.

Proofpoint’s purpose and culture, which defines how we, as individuals and as a company, act are built on the following tenets:

These cultural tenets allow our workforce to relentlessly pursue one of our central purposes: to earn our customers’ trust every day. We ~~also~~strive to earn this trust by:

As Proofpoint has grown, so have our programs continued to evolve to meet our colleagues’ needs, which we believe is essential to attract and retain employees of the highest caliber. We regularly and frequently communicate with and listen to our employees through small group surveys, interactive forums and townhalls, emails and online resources, to then iterate our processes and programs to improve the employee experience. For example, at our weekly townhall meetings, our CEO and other members of the executive team engage our global workforce with updates on the COVID-19 pandemic, our ongoing business operations, and other topics of interest.

Over the past year the employee experience has changed. They have encountered, observed and felt a ~~number of temporary~~transition from our traditional programs to virtual offerings that employees and ~~consultants. None~~their families can participate in, balancing a mix of live and on-demand activity. These online programs include educational classes taught by our fellow colleagues, mental health courses (mindfulness, resilience, meditation), cooking classes, financial well-being support, and “Vacation at Home” ideas. We realized that many of our parents sometimes need a little additional support, and because of this, Proofpoint created programming for Proofpoint kids, which included week-long STEAM camps during the summer, and offered ongoing story time, trivia games, art and dance, writing and oral presentation classes.

We launched in the summer of 2020, ProofpointEDU, a series of classes for Proofpoint kids taught by Proofpoint employees including topics like math, science, history, and cybersecurity for kids ages 5-15. Further, we introduced virtual team building programs such as trivia, bingo, escape rooms, and other group activities, all done via Zoom. Our Mindfulness program included music concerts, meditation, and resilience training.

In recognition of what we created for our employees, in July 2020, Proofpoint won the Espresa Innovation and Excellence Award for Culture Benefits.

The physical health, financial well-being, life balance and mental health of our employees is ~~represented by~~vital to the Company’s success. Throughout the year, we encourage healthy behaviors through regular communications, educational sessions, voluntary progress tracking, wellness challenges, and other incentives. Creating a ~~labor union with respect~~culture where all colleagues feel supported and valued is paramount to ~~his or her employment with us.~~ our corporate mission.

The ongoing COVID-19 pandemic has led to unique challenges and through it all, the health, safety, and the general well-being of our employees has remained our primary objective.

We ~~have not experienced any work stoppages~~embrace and foster the diversity of our team members, customers, stakeholders and consumers. Everyone is valued and appreciated for their unique backgrounds, experiences, thoughts and talents, all of which contributes to the growth and sustainability of our business. We strive to cultivate a culture and vision that supports and enhances the Company’s ability to recruit, develop and retain diverse talent at every level. As a global and distributed workforce, we recognize and celebrate our team members, their varied

backgrounds and cultures. Our career development opportunities are designed to foster inclusivity through ongoing career conversations that actively advance and develop people of all backgrounds.

We believe that diversity, inclusion, and opportunity is a journey and we ~~consider our relations with~~are committed to building a diverse and inclusive company and society for our employees, customers, partners, and shareholders. In order to create a more diverse and inclusive work environment, we provide education, training and tools so that all employees can become aware of bias, how it exists and how to mitigate it. As we continue to shape our work environment and world-class organization to be ~~good.~~more inclusive and inviting, we are actively striving to build an extensive pipeline of talent through various programs. Our internal programs enable and empower our hiring managers to identify alternative and emerging talent pools and to create an inclusive candidate experience.

Our talent strategy focuses on attracting the best talent, recognizing and rewarding their performance, while continually developing, engaging and retaining such talent. Our goal is to be the employer of choice within our market and peer groups. We strive to grow and develop the different capabilities and skills that we need for our future ~~success will depend upon our ability~~growth and strategy, while maintaining a robust pipeline of talent throughout the organization. We employ the best in the industry to ~~attract and retain qualified personnel. Competition for qualified personnel remains intense~~solve complex security challenges and we ~~may not be successful~~ensure their continued advancement and learning through internal and external development opportunities, such as provided by our own security awareness training platform and industry wide certification programs such as CISSP and CEH (“Certified Ethical Hacker”).

In addition, personal development opportunities are available to all employees through our learning programs, whose offerings include crucial conversations, time-management, and delegation. Our leadership development program, Elevate, is focused on building better leaders through personal growth, as well as building skills and tools for the modern leader. This investment in ~~retaining~~ our ~~key~~human capital ensures we are building a resilient and skilled workforce through career development and opportunities.

The Company is fully dedicated to conducting ourselves by the letter and in the spirit of the many laws and standards that apply to our business. Acting with honesty and integrity is a core cultural tenet at Proofpoint and we believe that conducting our business legally and ethically is foundational to our identity. The Company regularly re-enforces our commitment to ethics and integrity in employee communications from the CEO and other executive leaders, in our everyday actions and in processes and controls. As a part of our on-going efforts to ensure our employees conduct business with the highest levels of ethics and integrity, the Company mandates annual compliance training programs, provided in multiple languages for our global workforce. The Company encourages individuals to help it identify and raise ethical issues and concerns free of retaliation and to that end provides multiple means for individuals to report to the Board, management, the Company’s chief compliance officer, or ~~attracting skilled~~to legal or human resources personnel. In cases where any individual would feel more comfortable making a report anonymously, this is enabled via an online and telephonic ethics related hotline service.

We were incorporated in Delaware in 2002. Our principal executive offices are located at ~~892 Ross Drive,~~925 West Maude Avenue, Sunnyvale, California ~~94089,~~94085, and our telephone number is +1 (408) 517-4710. Our website is www.proofpoint.com.

Proofpoint, the Proofpoint logo, all of our product names and our other registered or common law trademarks, service marks, or trade names appearing in this Annual Report on Form 10-K are our property. Other trademarks appearing in this prospectus are the property of their respective holders.

For financial reporting purposes, net revenue and long-lived assets attributable to significant geographic areas are presented in Note 13, “Segment Reporting”, to the consolidated financial statements, which is incorporated herein by reference.

We file annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, proxy and information statements and amendments to reports filed or furnished pursuant to Sections 13(a), 14 and 15(d) of the Securities Exchange Act of 1934, as amended. The SEC also maintains a website at http://www.sec.gov that contains reports, proxy and information statements and other information regarding Proofpoint and other companies that file materials with the SEC electronically. The public may also obtain these filings at the Securities and Exchange Commission (“SEC”)’s Public Reference Room at 100 F Street, NE, Washington, DC 20549 or by calling the SEC at 1-800-SEC-0330. Copies of Proofpoint’s reports on Form 10-K, definitive Proxy Statements, Forms 10-Q and Forms 8-K, may be obtained, free of charge, electronically through our Internet website, https://investors.proofpoint.com/investors, or by sending an electronic message by visiting the Contact Us section within the investor relations portion of our website.

Investing in our common stock involves a high degree of risk. You should carefully consider the following risk factors, as well as the other information in this Annual Report on Form 10-K, including our consolidated financial statements and the related notes and "Management’s Discussion and Analysis of Financial Condition and Results of Operations" before deciding whether to invest in shares of our common stock. The occurrence of any of the events or developments described below, or of additional risks and uncertainties not presently known to us or that we currently deem immaterial, could materially and adversely affect our business, ~~financial condition,~~ results of ~~operation,~~operations, cash flows,financial condition and growth prospects. In such an event, the ~~trading~~market price of our common stock ~~may~~could decline and you ~~may~~could lose all or part of your investment.

Our business is subject to a number of risks and uncertainties, including those risks discussed at length below. These risks include, among others, the following:

We have a history of losses, and we are unable to predict the extent of any future losses or when, if ever, we will achieve profitability in the future.

We have incurred net losses in every year since our inception, including net losses of $163.8 million, $130.3 million and $103.7 million in 2020, 2019 and ~~$69.8 million in 2019,~~ 2018, ~~and 2017,~~ respectively. As a result, we had an accumulated deficit of ~~$725.6~~$889.4 million as of December 31, ~~2019.~~2020. Achieving profitability will require us to increase revenue, manage our cost structure, and avoid unanticipated liabilities. We do not expect to be profitable in the near term. Revenue growth may slow, or revenue may decline for a number of possible reasons,

including slowing demand for our solutions, increasing competition, a decrease in the growth of our overall market, or if we fail for any reason to continue to capitalize on growth opportunities. Any failure by us to obtain and sustain profitability, or to continue our revenue growth, could cause the price of our common stock to decline significantly.

We are unable to accurately predict the full extent to which the global COVID-19 pandemic may impact our business operations, financial performance, results of operations and stock price.

The COVID-19 pandemic continues to present extraordinary challenges in predicting future performance, and while we have modeled many scenarios and associated outcomes, there may be events that are more dire than we have modeled given the unique nature of this event. Although we are closely monitoring the impact of the COVID-19 pandemic and continually assess its potential effects on our business, our actual results could vary widely from our models. The extent to which our projections are affected by COVID-19 will largely depend on future developments, including the duration and spread of the outbreak, which still cannot be accurately predicted and remain uncertain. The COVID-19 pandemic or the perception of its effects could have a material adverse effect on our business, financial condition, results of operations, or cash flows.

Weakened global economic conditions may adversely affect our industry, business and financial results.

Our business depends on the overall demand for information technology and on the economic health of our current and prospective customers. Challenging economic conditions worldwide have from time to time contributed, and may continue to contribute, to slowdowns in the information technology industry, resulting in reduced demand for our solutions as a result of continued constraints on IT-related capital spending by our customers and increased price competition for our solutions. Further, any significant weakening of the economy in the United States or Europe and of the global economy, more limited availability of credit, a reduction in business confidence and activity, economic uncertainty and other difficulties, such as the COVID-19 pandemic, may affect one or more of the sectors or countries in which we sell our services. In addition, geopolitical developments, such as existing and potential trade wars and other events beyond our control, such as the COVID-19 pandemic, can increase levels of political and economic unpredictability globally and increase the volatility of global financial markets.

For example, current or potential customers have delayed and decreased and may continue to delay or decrease spending with us, or may not pay us or may delay paying us for previously performed services, given the impact that the COVID-19 pandemic has had and may continue to have on their business. Furthermore, the rate of customer terminations or service cancellations or failures to renew, which we refer to as churn, has and could also further increase as a result of the effects of the pandemic, which could include increased price competition or a reduction in customer spending. Due to restrictions on travel and in-person meetings, current or potential customers may also not be interested in taking sales meetings or cancel existing sales meetings with our sales representatives, which could materially lengthen our sales cycle and slow our sales growth. Any of these events could have an adverse effect on our business, operating results and financial position.

Our quarterly operating results and other metrics are likely to vary significantly and be unpredictable, which could cause the trading price of our stock to decline.

Our operating results and other metrics have historically varied from period to period, and we expect that they will continue to do so as a result of a number of factors, many of which are outside of our control and may be difficult to predict, including:

Any one of the factors above or the cumulative effect of some of the factors referred to above may result in significant fluctuations in our financial and other operating results, including fluctuations in our key metrics. This variability and unpredictability could result in our failing to meet the expectations of securities analysts or investors for any period. If we fail to meet or exceed such expectations for these or any other reasons, the market price of our shares could fall substantially and we could face costly lawsuits, including securities class action suits. In addition, a significant percentage of our operating expenses are fixed in nature and based on forecasted revenue and cash flow trends. Accordingly, in the event of revenue shortfalls, we are generally unable to mitigate the negative impact on margins or other operating results in the short term.

We may fail to meet or exceed the expectations of securities analysts and investors, and the market price for our common stock could decline. If one or more of the securities analysts who cover us change their recommendation regarding our stock adversely, the market price for our common stock could decline. Additionally, our stock price may be based on expectations, estimates or forecasts of our future performance that may be unrealistic or may not be achieved. Further, our stock price may be affected by financial media, including press reports and blogs.

Our customers may fail to pay us in accordance with the terms of their agreements, necessitating action by us to compel payment.

If customers fail to pay us under the terms of our agreements, we may be adversely affected both from the inability to collect amounts due and the cost of enforcing the terms of our contracts, including through litigation. The risk of such negative effects increases with the term length of our customer arrangements. Furthermore, some of our customers have attempted to and may continue to attempt to renegotiate contracts, seek bankruptcy protection or other similar relief and fail to pay amounts due to us, or pay those amounts more slowly, either of which could adversely affect our operating results, financial position and cash flow. The recent and ongoing global COVID-19 pandemic may also increase the likelihood, frequency and magnitude of these risks.

If we are unable to maintain high subscription renewal rates, our future revenue and operating results will be harmed.

Our customers have no obligation to renew their subscriptions for our solutions after the expiration of their initial subscription period, which typically ranges from one to three years. In addition, our customers may renew for fewer subscription services or users, renew for shorter contract lengths or renew at lower prices due to competitive or other pressures. We cannot accurately predict renewal rates and our renewal rates may decline or fluctuate as a result of a number of factors, including competition, customers’ IT budgeting and spending priorities, and deteriorating general economic ~~conditions.~~conditions, including as a result of the COVID-19 pandemic. If our customers do not renew their subscriptions for our solutions, our revenue would decline and our business would suffer.

If we are unable to sell additional solutions to our customers, our future revenue and operating results will be harmed.

Our future success depends on our ability to sell additional solutions to our customers. This may require increasingly sophisticated and costly sales efforts and may not result in additional sales. In addition, the rate at which our customers purchase additional solutions depends on a number of factors, including the perceived need for additional solutions, growth in the number of end users, and general economic conditions. If our efforts to sell additional solutions to our customers are not successful, our business may suffer.

If our solutions fail or are perceived to fail to protect our customers from security breaches, our brand and reputation could be harmed, which could have a material adverse effect on our business and results of operations.

The threats facing our customers are constantly evolving and the techniques used by attackers to access or sabotage data change frequently. As a result, we must constantly update our solutions to respond to these threats. If we fail to update our solutions in a timely or effective manner to respond to these threats, our customers could experience security breaches. Increasingly, companies are subject to a wide variety of attacks on their networks and systems, including traditional computer hackers, malicious code (such as viruses and worms), distributed denial-of-service attacks, sophisticated attacks conducted or sponsored by nation-states, advanced persistent threat intrusions, ransomware, and theft or misuse of intellectual property or business or personal data, including by disgruntled employees, former employees or contractors. Many federal, state and foreign governments have enacted laws requiring companies to notify individuals of data security breaches involving their personal data. These mandatory disclosures regarding a security breach often lead to widespread negative publicity, and any association of us with such publicity may cause our customers to lose confidence in the effectiveness of our data security measures. Any security breach at one of our customers or even an unproven allegation of a security breach at one of our customers, could harm our reputation as a secure and trusted company and could cause the loss of ~~customers.~~customers and sales, loss of competitive advantages over our competitors, increased costs to remedy any problems and otherwise respond to any incident, regulatory investigations and enforcement actions, costly litigation, and other liability. In addition, we may incur significant costs and operational consequences of investigating, remediating, eliminating and putting in place additional tools and devices designed to prevent actual or perceived security breaches and other security incidents, as well as the costs to comply with any notification obligations resulting from any security incidents. Similarly, if a well-publicized breach of data security at a customer of any other cloud‑based data protection or archiving service provider or other major enterprise cloud services provider were to occur, there could be a loss of confidence in the cloud‑based protection and storage of sensitive data and information generally.

In addition, our solutions work in conjunction with a variety of other elements in customers’ IT and security infrastructure, and we may receive blame and negative publicity for a security breach that may have been the result of the failure of one of the other elements not provided by us. The occurrence of a breach, whether or not caused by our solutions, or allegations of a breach, even if such allegations turn out to be untrue, could delay or reduce market acceptance of our solutions and have an adverse effect on our business and financial performance. In addition, any revisions to our solutions that we believe may be necessary or appropriate in connection with any such breach may cause us to incur significant expenses. We cannot assure you that any of our efforts to manage this risk, including adoption of a comprehensive incident response plan and process for detecting, mitigating, and investigating security incidents that we test through table-top exercises, testing of our security protocols through additional techniques, such as penetration testing, debriefing after security incidents, to improve our security and responses, and regular briefing of our directors and officers on our cybersecurity risks, preparedness, and management, will be effective in protecting us from such attacks. Any of these events could have material adverse effects on our brand and reputation, which could harm our business, financial condition, and operating results.

If our customers experience data losses and breaches via our products or solutions, our brand, reputation and business could be harmed.

Our customers rely on our archiving and other solutions to protect, transfer or store their corporate data, which may include financial records, credit card information, business information, health information, other personally identifiable information or other sensitive personal information. A breach of our network security and systems or other events that cause the loss or public disclosure of, or access by third parties to, our customers’ stored files or data could have serious negative consequences for our business, including possible fines, penalties and damages, reduced demand for our solutions, an unwillingness of our customers to use our solutions, harm to our brand and reputation, and time-consuming and expensive litigation. The techniques used to obtain unauthorized access, disable or degrade service, or sabotage systems change frequently, often are not recognized until launched against a target, and may originate from less regulated or remote areas around the world. As a result, we may be unable to proactively prevent these techniques, implement adequate preventative or reactionary measures, or enforce the laws and regulations that govern such activities. In addition, because of the large amount of data that we collect and manage, it is possible that hardware failures, insider errors or malfeasance or errors in our systems could result in data loss or corruption, or cause the information that we collect to be incomplete or contain inaccuracies that our customers regard as significant. If our customers experience any data loss, or any data corruption or inaccuracies, whether caused by security breaches or otherwise, our brand, reputation and business would be harmed.

Our insurance may be inadequate or may not be available in the future on acceptable terms, or at all. In addition, our policy may not cover any claim against us for loss of data or other indirect or consequential damages. Defending a suit based on any data loss or system disruption, regardless of its merit, could be costly and divert management’s attention.

Defects or vulnerabilities in our solutions could harm our reputation, reduce the sales of our solutions and expose us to liability for losses.

Because our solutions are complex, undetected errors, failures or bugs may occur, especially when solutions are first introduced or when new versions or updates are released, or when we introduce an acquired company’s products of services, despite our efforts to test those solutions and enhancements prior to release. This includes not only vulnerabilities that are specific to our solutions, but also vulnerabilities that impact the third-party or open source software or services that we use or the hardware that we rely on for our solutions. Additionally, we may be impacted by the evaluation of the security of our services by third party security scoring companies whether those evaluations are accurate or not. We may not be able to correct defects, errors, vulnerabilities or failures promptly, or ~~at all or~~ to correct inaccuracies in perceptions about these ~~matters.~~matters at all.

Any defects, errors, vulnerabilities or failures in our solutions could result in:

Limitation of liability provisions in our standard terms and conditions and our other agreements may not adequately or effectively protect us from any claims related to defects, errors, vulnerabilities or failures in our solutions, including as a result of federal, state or local laws or ordinances or unfavorable judicial decisions in the United States or other countries.

Our software, website, hosted and internal systems may be subject to intentional disruption or penetration from external attackers or insiders that could adversely impact our reputation and future sales.

We could be a target of attacks specifically designed to impede the performance of our solutions, redirect users to malicious sites, harm our reputation and brand, or misappropriate our or our customers’ proprietary information. Similarly, experienced computer hackers may attempt to penetrate our network or other security or the security of our website or other hosted or internal systems or to trick our employees into taking actions that compromise our security (such as via phishing or business email compromise attacks) in order to misappropriate proprietary information and/or cause interruptions of our services and/or expose perceived security vulnerabilities. It is also possible that systems may be disrupted or our sensitive information or the information of our customers might be exposed due to malfeasance or errors by employees or contractors. Because the techniques used by attackers to access or sabotage networks and compromise our systems and information change frequently and may not be recognized until launched against a target, we may be unable to anticipate these techniques. If an actual or perceived breach of network security occurs as a result of third-party action, including cyber-attacks or other intentional misconduct by computer hackers conducted or sponsored by nation-states, error or malfeasance by insiders, or otherwise, it could adversely affect the market perception of our company and our solutions, ~~and~~ may expose us to the loss of information, litigation and possible ~~liability.~~liability, and could cause a loss in revenue due to reputational or brand damage and customer churn. In addition, such a security breach could impair our ability to operate our business, including our ability to provide support services to our customers.

Our solutions may collect, filter and store customer data which may contain personal information, which raises privacy concerns and could result in us having liability or inhibit sales of our solutions.

Many federal, state and foreign government bodies and agencies have adopted or are considering adopting laws and regulations regarding the collection, use, and disclosure of personal information. Because many of the features of our solutions use, store, and report on customer data which may contain personal information from our customers, any inability to adequately address

privacy concerns, or comply with applicable privacy laws, regulations and policies could, even if unfounded, result in liability to us, damage to our reputation, loss of sales, and harm to our business. Furthermore, the costs of compliance with, and other burdens imposed by, such laws, regulations and policies that are applicable to the businesses of our customers may limit the use and adoption of our solutions and reduce overall demand for them. Privacy concerns, whether or not valid, may inhibit market adoption of our solutions. For example, in the United States regulations such as the Gramm‑Leach‑Bliley Act, which protects and restricts the use of consumer credit and financial information, and HIPAA which regulates the use and disclosure of personal health information, impose significant security and data protection requirements and obligations on businesses that may affect the use and adoption of our solutions. Similarly, we hold a FedRAMP authorization without which we would not be able to provide services and products to certain US federal entities.

In the past we have relied on U.S.-European Union Frameworks for transatlantic data flows such as the ~~EU-US~~EU-U.S. Privacy Shield, for which we self-certified under the ~~EU-US~~EU-U.S. Privacy Shield framework on October 5, 2016. However, Privacy Shield is currently being challenged in European Union (“EU”) courts, and on July 16, 2020, the Court of Justice of the EU issued a decision invalidating outright the EU-U.S. Privacy Shield framework, so there is some uncertainty regarding its future validity and our ability to rely on it for EU to US data transfers. We also rely on Standard Contractual Clauses (“SCCs”) authorized by the EU’s Data Protection Directive of 1995 for transatlantic data flows, but the SCCs are also being challenged in EU courts, so there is some uncertainty regarding our ability to rely on SCCs in the future for EU to US data transfer. Additionally, the EU’s General Data

Protection Regulation, began to be enforced on May 25, 2018, and carries with it significantly increased responsibilities and potential penalties for companies that process EU personal data. We have seen increased customer attention surrounding EU Data Privacy. Furthermore, outside of the EU, we continue to see increased regulation of data privacy and security, including the adoption of more stringent subject matter specific state laws (such as the New York Department of Financial Services’ Cybersecurity Regulation, ~~and~~ the ~~new~~ California Consumer Privacy Act of 2018 that became effective January 1, ~~2020)~~2020, and the new California Privacy Rights Act), national laws regulating the collection and use of data, and security and data breach obligations. The uncertainty and changes in the requirements of multiple jurisdictions may increase the cost of compliance, delay or reduce demand for our services, restrict our ability to offer services in certain locations, impact our customers’ ability to deploy our solutions in certain jurisdictions, or subject us to sanctions, by national data protection regulators, all of which could harm our business, financial condition and results of operations.

The regulatory framework for privacy issues is evolving worldwide, and various government and consumer agencies and public advocacy groups have called for new regulation and changes in industry practices. It is possible that new laws and regulations will be adopted in the United States and internationally, or existing laws and regulations may be interpreted in new ways, that would affect our business. Complying with any new regulatory requirements could force us to incur substantial costs or require us to change our business practices in a manner that could reduce our revenue or compromise our ability to effectively pursue our growth strategy.

Any failure or perceived failure to comply with laws and regulations or loss of certifications such as the FedRAMP authorization may result in proceedings or actions against us by government entities or others, or could cause us to lose users and customers, which could potentially have an adverse effect on our business.

We operate in a highly competitive environment with large, established competitors, and our competitors may gain market share in the markets for our solutions that could adversely affect our business and cause our revenue to decline.

Our traditional competitors include security‑focused software vendors, such as ~~Symantec Corporation (whose enterprise security business was recently acquired by~~ Broadcom Inc.) and Cisco Systems, Inc., which offer software products that directly compete with our solutions. In addition to competing with these vendors directly for sales to customers, we compete with them for the opportunity to have our solutions bundled with the product offerings of our strategic partners. Our competitors could gain market share from us if any of these partners replace our solutions with the products of our competitors or if these partners more actively promote our competitors’ products over our solutions. In addition, software vendors who have bundled our solutions with theirs may choose to bundle their software with their own or other vendors’ software, or may limit our access to standard product interfaces and inhibit our ability to develop solutions for their platform.

We also face competition from large technology companies, such as Broadcom Inc., Cisco Systems, Inc., Google Inc., Micro Focus International plc and Microsoft Corporation. These companies are increasingly developing and incorporating into their products features that compete on various levels with our solutions. Our competitive position could be adversely affected to the extent that our customers perceive that the functionality incorporated into these products would replace the need for our solutions or that buying from one vendor would provide them with increased leverage and purchasing power and a better customer experience. We also face competition from independent security vendors such as FireEye, Inc. that offer network security products and many smaller companies like ~~Barracuda Networks, Inc. and~~ Mimecast Ltd that specialize in particular segments of the markets in which we compete.

Many of our competitors have greater financial, technical, sales, marketing or other resources than we do and consequently may have the ability to influence our customers to purchase their products instead of ours. Further consolidation within our industry or other changes in the competitive environment could also result in larger competitors that compete with us on several levels. In addition, acquisitions of smaller companies by large technology companies that specialize in particular segments of the markets in which we compete would result in increased competition from these large technology companies. If we are unsuccessful in responding to our competitors or to changing technological and customer demands, our competitive position and financial results could be adversely affected.

If we do not effectively expand and train our sales force, we may be unable to add new customers or increase sales to our existing customers and our business will be harmed.

We continue to be substantially dependent on our sales force to obtain new customers and to sell additional solutions to our existing customers. We believe that there is significant competition for sales personnel with the skills and technical knowledge that we require. Our ability to achieve significant revenue growth will depend, in large part, on our success in recruiting, training and retaining sufficient numbers of sales personnel. New hires require significant training and may take significant time before they achieve full ~~productivity.~~productivity, a period which may be prolonged due to the remote working arrangements we have adopted due to the COVID-19 pandemic. Our recent hires and planned hires may not become as productive as we expect, and we may be unable to hire or retain sufficient numbers of qualified individuals in the markets where we do business or plan to do business. If we are unable to hire and train sufficient numbers of effective sales personnel, or the sales personnel are not successful in obtaining new customers or increasing sales to our existing customer base, our business will be harmed.

Our sales cycle is long and unpredictable, and our sales efforts require considerable time and expense. As a result, our results are difficult to predict and may vary substantially from quarter to quarter, which may cause our operating results to fluctuate.

We sell our security and compliance offerings primarily to enterprise IT departments that are managing a growing set of user and compliance demands, which has increased the complexity of customer requirements to be met and confirmed in the sales cycle. Increasingly, we have found that security, legal and compliance departments are involved in testing, evaluating and finally approving purchases, which has also made the sales cycle longer and less predictable. We may not be able to accurately predict or forecast the timing of sales, which makes our future revenue difficult to predict and could cause our results to vary significantly. In addition, we might devote substantial time and effort to a particular unsuccessful sales effort, and as a result we could lose other sales opportunities or incur expenses that are not offset by an increase in revenue, which could harm our business.

Because our long-term success depends, in part, on our ability to expand the sales of our platform to our customers located outside of the United States, our business will be increasingly susceptible to risks associated with international operations.

One key element of our growth strategy is to develop a worldwide customer base and expand our operations worldwide, such as by adding employees, offices and customers internationally, particularly in Europe and Asia.

Operating in international markets requires significant resources and management attention and will subject us to regulatory, economic, political and competitive risks and competition that are different from those in the United States.

In addition, our international operations may fail to succeed due to other risks inherent in operating businesses internationally, including:

In addition, the ~~current~~prior U.S. administration has ~~recently~~ instituted or proposed changes to foreign trade policy including the negotiation or termination of trade agreements, the imposition of tariffs on products imported from certain countries, economic

sanctions on individuals, corporations or countries and other government regulations affecting trade between the United States and other countries in which we do business. ~~New or increased tariffs and other changes in U.S. trade policy could trigger retaliatory actions by affected countries, and~~As a result, certain foreign governments have instituted or are considering imposing trade sanctions on certain U.S. manufactured goods. The escalation of protectionist or retaliatory trade measures in either the United States or any other countries in which we do business, such as a change in tariff structures, export compliance or other trade policies, may increase the cost of, or otherwise interfere with, conducting our business.

Our failure to manage any of these risks successfully could harm our existing and future international operations and seriously impair our overall business.

If we are unable to enhance our existing solutions and develop new solutions, our growth will be harmed, and we may not be able to achieve profitability.

Our ability to attract new customers and increase revenue from existing customers will depend in large part on our ability to enhance and improve our existing solutions and to introduce new solutions. The success of any enhancement or new solution depends on several factors, including the timely completion, introduction and market acceptance of the enhancement or solution. Any new enhancement or solution we develop or acquire may not be introduced in a timely or cost-effective manner and may not achieve the broad market acceptance necessary to generate significant revenue. If we are unable to successfully develop or acquire new solutions or enhance our existing solutions to meet customer requirements, we may not grow as expected and we may not achieve profitability.

We cannot be certain that our development activities will be successful or that we will not incur delays or cost overruns. Furthermore, we may not have sufficient financial resources to identify and develop new technologies and bring enhancements or new solutions to market in a timely and cost-effective manner. New technologies and enhancements could be delayed or cost more than we expect, and we cannot ensure that any of these solutions will be commercially successful if and when they are introduced.

If we are unable to cost-effectively scale or adapt our existing architecture to accommodate increased traffic, technological advances or changing customer requirements, our operating results could be harmed.

As our customer base grows, the number of users accessing our solutions over the Internet will correspondingly increase. Increased traffic could result in slow access speeds and response times. Since our customer agreements often include service availability commitments, slow speeds or our failure to accommodate increased traffic could result in breaches of our service level agreements or obligate us to issue service credits. In addition, the market for our solutions is characterized by rapid technological advances and changes in customer and regulatory requirements. In order to accommodate increased traffic and respond to technological advances and evolving customer and regulatory requirements, we expect that we will be required to make future investments in our network architecture. If we do not implement future upgrades to our network architecture cost-effectively, or if we experience prolonged delays or unforeseen difficulties in connection with upgrading our network architecture, our service quality may suffer, and our operating results could be harmed.

If we fail to manage our sales and distribution channels effectively or if our partners choose not to market and sell our solutions to their customers, our operating results could be adversely affected.

We have derived and anticipate that in the future we will continue to derive a substantial portion of the sales of our solutions through channel partners. In order to scale our channel program to support growth in our business, it is important that we continue to help our partners enhance their ability to independently sell and deploy our solutions. We may be unable to continue to successfully expand and improve the effectiveness of our channel sales program.

Our agreements with our channel partners are generally non-exclusive and some of our channel partners have entered, and may continue to enter, into strategic relationships with our competitors or are competitors themselves. Further, many of our channel partners have multiple strategic relationships and they may not regard us as significant for their businesses. Our channel partners may terminate their respective relationships with us with limited or no notice and with limited or no penalty, pursue other partnerships or

relationships, or attempt to develop or acquire products or services that compete with our solutions. Our partners also may impair our ability to enter into other desirable strategic relationships. If our channel partners do not effectively market and sell our solutions, if they choose to place greater emphasis on products of their own or those offered by our competitors, or if they fail to meet the needs of our customers, our ability to grow our business and sell our solutions may be adversely affected. Similarly, the loss of a substantial number of our channel partners, and our possible inability to replace them, the failure to recruit additional channel partners, any reduction or delay in their sales of our solutions, or any conflicts between channel sales and our direct sales and marketing activities could materially and adversely affect our results of operations.

Because we recognize revenue from subscriptions over the term of the relevant service period, decreases or increases in sales are not immediately reflected in full in our operating results.

We recognize revenue from subscriptions over the term of the relevant service period, which typically range from one to three years, with some up to five years. As a result, most of our quarterly revenue from subscriptions results from agreements entered into

during previous quarters. Consequently, a shortfall in demand for our solutions in any quarter may not significantly reduce our subscription revenue for that quarter, but could negatively affect subscription revenue in future quarters. We may be unable to adjust our cost structure to compensate for this potential shortfall in subscription revenue. Accordingly, the effect of significant downturns in sales of subscriptions may not be fully reflected in our results of operations until future periods. Our subscription model also makes it difficult for us to rapidly increase our subscription revenue through additional sales in any period, as subscription revenue must be recognized over the term of the contract.

~~Interruptions~~Any interruptions or delays in services provided through our internal operations or by ~~third parties~~third-parties, including data center hosting facilities, network service providers, cloud computing platform providers and other hardware and software vendors, or from our inability to adequately plan for and manage service interruptions or infrastructure capacity requirements, could impair the delivery of our ~~service~~services and harm our business.

Our business operations are subject to interruption by natural disasters, fire, power shortages, pandemics (including the ongoing COVID-19 pandemic) and other events beyond our control. We rely on a number of third-party providers for data center hosting facilities, equipment, maintenance and other services, and the loss of, or problems with, one or more of these providers or our internal operations and infrastructure, including any potential disruptions due to significantly increased global demand on certain cloud-based systems during the COVID-19 pandemic, may impact our ability to properly maintain and repair our systems, thereby causing us to lose customers.

We currently serve our customers from third‑party data center facilities and resources located in the United States, Canada, Australia and Europe. We also rely on bandwidth providers, Internet service providers, mobile networks and other third-party IT service providers to operate our business and to deliver our solutions. Any damage to, or failure or disruption of, the systems of our third‑party providers could result in interruptions to our service. If for any reason our arrangement with one or more of our data centers is terminated, we could experience additional expense in arranging for new facilities and support. Our data center facilities providers have no obligations to renew their agreements with us on commercially reasonable terms, or at all. If we are unable to renew our agreements with the facilities providers on commercially reasonable terms or if in the future, we add additional data center facility providers, we may experience costs or downtime in connection with the transfer to, or the addition of, new data center facilities. In addition, the failure of our data centers to meet our capacity requirements could result in interruptions in the availability of our solutions, impair the functionality of our solutions or impede our ability to scale our operations. As we continue to add data centers, restructure our data management plans, and increase capacity in existing and future data centers, we may move or transfer our data and our customers’ data. Despite precautions taken during such processes and procedures, any unsuccessful data transfers may impair the delivery of our service, and we may experience costs or downtime in connection with the transfer of data to other facilities. Similarly, some of our solutions’ features run or depend on IT services run by third parties, such as data feeds or public clouds, such as ~~AWS~~Amazon Web Services and Google Cloud, and an extended failure of such services might materially and adversely impact our ability to provide our services to our customers. Furthermore, some of our sales and business operations, such as CRM and billing and invoicing depend in part on third-party IT service providers and if those services were to be unavailable for extended periods of time it might materially and adversely affect our ability to operate.

We also depend on access to the Internet through third‑party bandwidth providers to operate our business. If we lose the services of one or more of our bandwidth providers, or if these providers experience outages, for any reason, we could experience disruption in delivering our solutions or we could be required to retain the services of a replacement bandwidth provider. Our business also depends on our customers having high-speed access to the Internet. Any Internet outages or delays could adversely affect our ability to provide our solutions to our customers.

Our operations rely heavily on the availability of electricity, which also comes from third-party providers. If we or the third-party data center facilities that we use to deliver our services were to experience a major power outage or if the cost of electricity were to increase significantly, our operations and financial results could be harmed. If we or our third‑party data centers were to experience a major power outage, we or they would have to rely on back-up generators, which might not work properly or might not provide an adequate power supply during a major power outage. Such a power outage could result in a significant disruption of our business.

For example, the COVID-19 pandemic and its adverse effects have become more prevalent in the locations where we conduct business and as a result, we have begun to experience more pronounced disruptions in our daily internal operations, including the closures of our physical domestic and international offices to promote the safety and security of our employees and to support the communities in which we operate. We have instituted remote working arrangements for employees where practicable, resulting in potential latent inefficiencies that may impact our operations.

Although we maintain crisis management and disaster response plans, including our business continuity plan, such events could make it difficult or impossible for us to deliver our services to our customers, could lead to lengthy interruptions in our service, and could decrease demand for our services. The occurrence of an extended interruption of our or third‑party services for any reason could result in lengthy interruptions in our services or in the delivery of customers’ email and require us to provide service credits, refunds, indemnification payments or other payments to our customers, and could also result in the loss of customers. ~~While we have~~Additionally, any such system failures or outages could compromise our ability to conduct business ~~continuity~~or delay our financial reporting, which could materially affect our operating results and ~~disaster recovery plans and contingencies in place, there can be no assurance that they will be adequate in the event of an extended or severe disruption.~~financial condition.

Any failure to offer or the inability of our customers to access our high-quality technical support services may adversely affect our relationships with our customers and harm our financial results.

Once our solutions are deployed, our customers depend on accessing our support organization to resolve any technical issues relating to our ~~solutions.~~solutions, which may be impaired by interruptions caused by natural disasters, fire, power shortages, pandemics (including the ongoing COVID-19 pandemic) and other events beyond our control. In addition, our sales process is highly dependent on our solutions and business reputation and on strong recommendations from our existing customers. Any failure to maintain or the inability of our customers to access our high-quality technical support, or a market perception that we do not maintain high-quality support or the inability of our customers to access our high-quality support, could harm our reputation, adversely affect our ability to sell our solutions to existing and prospective customers, and harm our business, operating results and financial condition.

We offer technical support services with many of our solutions. We may be unable to respond quickly enough to accommodate short-term increases in customer demand for support services. We also may be unable to modify the format of our support services to compete with changes in support services provided by competitors. Increased customer demand for these services, without corresponding revenue, could increase costs and adversely affect our operating results.

We have outsourced a substantial portion of our worldwide customer support functions to third‑party service providers. If these companies experience financial difficulties, do not maintain sufficiently skilled workers and resources to satisfy our contracts, or otherwise fail to perform at a sufficient level, the level of support services to our customers may be significantly disrupted, which could materially harm our reputation and our relationships with these customers.

We believe that developing and maintaining awareness and integrity of our company and our brand are important to achieving widespread acceptance of our existing and future offerings and are important elements in attracting new customers. We believe that the importance of brand recognition will increase as competition in our market further intensifies. Successful promotion of our brand will depend on the effectiveness of our marketing efforts and on our ability to provide reliable and useful solutions at competitive prices. We plan to continue investing substantial resources to promote our brand, both domestically and internationally, but there is no guarantee that our brand development strategies will enhance the recognition of our brand. Some of our existing and potential competitors have well-established brands with greater recognition than we have. If our efforts to promote and maintain our brand are not successful, our operating results and our ability to attract and retain customers may be adversely affected. In addition, even if our brand recognition and loyalty increase, this may not result in increased use of our solutions or higher revenue.

In addition, independent industry analysts often provide reviews of our solutions, as well as those of our competitors, and perception of our solutions in the marketplace may be significantly influenced by these reviews. We have no control over what these industry analysts report, and because industry analysts may influence current and potential customers, our brand could be harmed if they do not provide a positive review of our solutions or view us as a market leader.

The steps we have taken to protect our intellectual property rights may not be adequate.

We rely on a combination of contractual rights, trademarks, trade secrets, patents and copyrights to establish and protect our intellectual property rights. These offer only limited protection, however, and the steps we have taken to protect our proprietary technology may not deter its misuse, theft or misappropriation. Any of our patents, copyrights, trademarks or other intellectual property rights may be challenged by others or invalidated through administrative process or litigation. Competitors may independently develop technologies or products that are substantially equivalent or superior to our solutions or that inappropriately incorporate our proprietary technology into their products. Competitors may hire our former employees who may misappropriate our proprietary technology or misuse our confidential information. Although we rely in part upon confidentiality agreements with our employees, consultants and other third parties to protect our trade secrets and other confidential information, those agreements may not effectively prevent disclosure of trade secrets and other confidential information and may not provide an adequate remedy in the event of misappropriation of trade secrets or unauthorized disclosure of confidential information. In addition, others may

independently discover our trade secrets and confidential information, and in such cases, we could not assert any trade secret rights against such parties.

We might be required to spend significant resources to monitor and protect our intellectual property rights. We may initiate claims or litigation against third parties for infringement of our intellectual property rights or misappropriation of our trade secrets, or to establish the validity of our intellectual property rights. Any litigation, whether or not it is resolved in our favor, could result in significant expense to us and divert the efforts of our technical and management personnel, which may adversely affect our business, operating results and financial condition. Certain jurisdictions may not provide adequate legal infrastructure for effective protection of our intellectual property rights. Changing legal interpretations of liability for unauthorized use of our solutions or lessened sensitivity by corporate, government or institutional users to refraining from intellectual property piracy or other infringements of intellectual property could also harm our business.

Our issued patents may not provide us with any competitive advantages or may be challenged by third parties, and our patent applications may never be granted at all. It is possible that innovations for which we seek patent protection may not be protectable. Additionally, the process of obtaining patent protection is expensive and time consuming, and we may not be able to prosecute all necessary or desirable patent applications at a reasonable cost or in a timely manner. Given the cost, effort, risks and downside of obtaining patent protection, including the requirement to ultimately disclose the invention to the public, we may not choose to seek patent protection for certain innovations. However, such patent protection could later prove to be important to our business. Even if issued, there can be no assurance that any patents will have the coverage originally sought or adequately protect our intellectual property, as the legal standards relating to the validity, enforceability and scope of protection of patent and other intellectual property rights are uncertain. Any patents that are issued may be invalidated or otherwise limited, or may lapse or may be abandoned, enabling other companies to better develop products that compete with our solutions, which could adversely affect our competitive business position, business prospects and financial condition.

We cannot assure you that the measures we have taken to protect our intellectual property will adequately protect us, and any failure to protect our intellectual property could harm our business.

Third parties claiming that we infringe their intellectual property rights could cause us to incur significant legal expenses and prevent us from selling our solutions.

Companies and individuals in the software and technology industries, including some of our current and potential competitors, own large numbers of patents, copyrights, trademarks and trade secrets and frequently enter into litigation based on allegations of infringement, misappropriation or other violations of intellectual property rights. In addition, many of these third parties have the capability to dedicate substantially greater resources to enforce their intellectual property rights and to defend claims that may be brought against them. The litigation may involve patent holding companies or other adverse patent owners who have no

relevant product revenue and against whom our potential patents may provide little or no deterrence. We have received, and may in the future receive, notices that claim we have infringed, misappropriated or otherwise violated other parties’ intellectual property rights. We have been involved in litigation involving such allegations of infringement. To the extent we gain greater visibility, we could face a higher risk of being the subject of intellectual property infringement claims, which is not uncommon with respect to software technologies in general and information security technology in particular. There may be third‑party intellectual property rights, including issued or pending patents that cover significant aspects of our technologies or business methods. Any intellectual property claims, with or without merit, could be very time consuming, could be expensive to settle or litigate and could divert our management’s attention and other resources. These claims could also subject us to significant liability for damages, potentially including treble damages if we are found to have willfully infringed patents or copyrights. These claims could also result in our having to stop using technology found to be in violation of a third-party’s rights. We might be required to seek a license for the intellectual property, which may not be available on reasonable terms or at all. Even if a license were available, we could be required to pay significant royalties, which would increase our operating expenses. As a result, we may be required to develop alternative non-infringing technology, which could require significant effort and expense. If we cannot license or develop technology for any infringing aspect of our business, we would be forced to limit or stop sales of one or more of our solutions or features of our solutions and may be unable to compete effectively. Any of these results would harm our business, operating results and financial condition.

In addition, our agreements with customers and channel partners include indemnification provisions under which we agree to indemnify them for losses suffered or incurred as a result of claims of intellectual property infringement and, in some cases, for damages caused by us to property or persons. Large indemnity payments could harm our business, operating results and financial condition.

We rely on technology and intellectual property licensed from other parties, the failure or loss of which could increase our costs and delay or prevent the delivery of our solutions.

We utilize various types of software and other technology, as well as intellectual property rights, licensed from unaffiliated third parties in order to provide certain elements of our solutions. Any errors or defects in any third‑party technology could result in errors in our solutions that could harm our business. In addition, licensed technology and intellectual property rights may not continue to be available on commercially reasonable terms, or at all. While we believe that there are currently adequate replacements for the

third‑party technology we use, any loss of the right to use any of this technology on commercially reasonable terms, or at all, could result in delays in producing or delivering our solutions until equivalent technology is identified and integrated, which delays could harm our business. In this situation we would be required to either redesign our solutions to function with software available from other parties or to develop these components ourselves, which would result in increased costs. Furthermore, we might be forced to limit the features available in our current or future solutions. If we fail to maintain or renegotiate any of these technology or intellectual property licenses, we could face significant delays and diversion of resources in attempting to develop similar or replacement technology, or to license and integrate a functional equivalent of the technology.

Some of our solutions contain “open source” software, and any failure to comply with the terms of one or more of these open source licenses could negatively affect our business.

Some of our solutions are distributed with software licensed by its authors or other third parties under so-called “open source” licenses, which may include, by way of example, the GNU General Public License, or GPL, and the Apache License. Some of these licenses contain requirements that we make available source code for modifications or derivative works we create based upon the open source software, and that we license such modifications or derivative works under the terms of a particular open source license or other license granting third parties certain rights of further use. By the terms of certain open source licenses, we could be required to release the source code of our proprietary software, and to make our proprietary software available under open source licenses, if we combine our proprietary software with open source software in a certain manner. In the event that portions of our proprietary software are determined to be subject to an open source license, we could be required to publicly release the affected portions of our source code, re-engineer all or a portion of our technologies, or otherwise be limited in the licensing of our technologies, each of which could reduce or eliminate the value of our technologies and solutions. In addition to risks related to license requirements, usage of open source software can lead to greater risks than use of third-party commercial software, as open source licensors generally do not provide warranties or controls on the origin of the software. We have established processes to help alleviate these risks, including a review process for screening requests from our development organizations for the use of open source software, but we cannot be sure that all open source software is submitted for approval prior to use in our solutions, that our programmers have not incorporated open source software into our proprietary solutions and technologies or that they will not do so in the future. In addition, many of the risks associated with usage of open source software cannot be eliminated, and could, if not properly addressed, negatively affect our business.

Governmental regulations affecting the export of certain of our solutions could negatively affect our business.

Some of our products are subject to U.S. export controls, and we incorporate encryption technology into certain of our products. These encryption products and the underlying technology may be exported outside the United States only with the required export authorizations, including by license, a license exception or other appropriate government authorizations, including the filing of an encryption registration. Governmental regulation of encryption technology and regulation of imports or exports, or our failure to obtain required import or export approval for our products, could harm our international sales and adversely affect our revenue.

Failure to comply with such regulations, whether by us or companies that we have acquired, in the future could result in penalties, costs, and restrictions on export privileges, which could also harm our operating results.

We have, and may further, expand through acquisitions of, or investments in, other companies, which may divert our management’s attention, dilute our stockholders’ ownership interests and consume corporate resources that otherwise would be necessary to sustain and grow our business.

We have made multiple acquisitions in the past, and our business strategy may, from time to time, continue to include acquiring complementary products, technologies or businesses. We also may enter into relationships with other businesses in order to expand our solutions, which could involve preferred or exclusive licenses, additional channels of distribution, or investments by or between the two parties. Negotiating these transactions can be time consuming, difficult and expensive, and our ability to close these transactions may be subject to third‑party approvals, such as government regulation, which are beyond our control. Consequently, we can make no assurance that these transactions, once undertaken and announced, will close.

These transactions may result in unforeseen operating difficulties and expenditures. In particular, we may encounter difficulties assimilating or integrating the businesses, technologies, products, personnel or operations of acquired companies, particularly if the key personnel of the acquired business choose not to work for us, and we may have difficulty retaining the customers of any acquired business. Acquisitions may also disrupt our ongoing business, divert our resources and require significant management attention that would otherwise be available for development of our business. Any acquisition or investment could expose us to unknown liabilities.

In addition, as of December 31, ~~2019,~~2020, we had ~~$873.5~~$818.8 million in goodwill and intangible assets, net of accumulated amortization, recorded on our balance sheet. We will incur expenses related to the amortization of intangible assets and we may in the future need to incur charges with respect to the impairment of goodwill or intangible assets, which could adversely affect our operating results. Moreover, we cannot assure you that the anticipated benefits of any acquisition or investment would be realized or that we would not be exposed to unknown liabilities. In connection with these types of transactions, we may issue additional equity securities that would dilute our stockholders’ ownership interests, use cash that we may need in the future to operate our business, incur debt on terms unfavorable to us or that we are unable to repay, incur large charges or substantial liabilities, encounter difficulties integrating diverse business cultures, and become subject to adverse tax consequences, substantial depreciation or deferred compensation charges. These challenges related to acquisitions or investments could adversely affect our business, operating results and financial condition.

If we are unable to attract and retain qualified employees, lose key personnel, fail to integrate replacement personnel successfully, or fail to manage our employee base effectively, we may be unable to develop new and enhanced solutions, effectively manage or expand our business, or increase our revenue.

Our future success depends upon our ability to recruit and retain key management, technical, sales, marketing, finance, and other critical personnel. Competition for qualified management, technical and other personnel is intense, and we may not be successful in attracting and retaining such personnel. If we fail to attract and retain qualified employees, our ability to grow our business could be harmed. Our officers and other key personnel are employees-at-will, and we cannot assure you that we will be able to retain them. Competition for people with the specific skills that we require is significant. In order to attract and retain personnel in a competitive marketplace, we believe that we must provide a competitive compensation package, including cash and equity‑based compensation. Volatility in our stock price may from time to time adversely affect our ability to recruit or retain employees. If we lose the services of our senior management or other key personnel, including due to illness resulting from COVID-19, if we are unable to hire and retain qualified employees, or conversely, if we fail to manage employee performance or reduce staffing levels when required by market conditions, our business and operating results could be adversely affected.

In addition, hiring, training, and successfully integrating replacement personnel could be time consuming, may cause additional disruptions to our operations, and may be unsuccessful, which could negatively impact future revenue.

Changes in laws and/or regulations related to the Internet or changes in the Internet infrastructure itself may diminish the demand for our solutions, and could have a negative impact on our business.

The future success of our business depends upon the continued use of the Internet as a primary medium for commerce, communication and business applications. Federal, state or foreign government bodies or agencies have in the past adopted, and may in the future adopt, laws or regulations affecting data privacy and the use of the Internet as a commercial medium. Changes in these laws or regulations could require us to modify our solutions in order to comply with these changes. In addition, government agencies or private organizations may begin to impose taxes, fees or other charges for accessing the Internet or commerce conducted via the Internet. These laws or charges could limit the growth of Internet‑related commerce or communications generally, result in a decline in the use of the Internet and the viability of Internet‑based applications such as ours and reduce the demand for our solutions.

The legal and regulatory framework also drives demand for our solutions. Our customers are subject to laws, regulations and internal policies that mandate how they process, handle, store, use and transmit a variety of sensitive data and communications. These laws and regulations are subject to revision, change and interpretation at any time, and any such change could either help or hurt the demand for our solutions. We cannot be sure that the legal and regulatory framework in any given jurisdiction will be favorable to our business or that we will be able to sustain or grow our business if there are any adverse changes to these laws and regulations.

~~If we are required to collect sales and use taxes on the solutions we sell, we may be subject to liability for past sales and our future sales may decrease.~~

State and local taxing jurisdictions have differing rules and regulations governing sales and use taxes, and these rules and regulations are subject to varying interpretations that may change over time. In particular, the applicability of sales taxes to our subscription services in various jurisdictions is unclear. It is possible that we could face sales tax audits and that our liability for these taxes could exceed our estimates as state tax authorities could still assert that we are obligated to collect additional amounts as taxes from our customers and remit those taxes to those authorities. We could also be subject to audits with respect to state and international jurisdictions for which we have not accrued tax liabilities. A successful assertion that we should be collecting additional sales or other taxes on our services in jurisdictions where we have not historically done so and do not accrue for sales taxes could result in substantial tax liabilities for past sales, discourage customers from purchasing our application or otherwise harm our business and operating results.

~~Adverse conditions in the national and global economies and financial markets may adversely affect our business and financial results.~~

Adverse macroeconomic conditions could negatively affect our customers, thereby impacting our business, operating results or financial condition. Challenging economic conditions worldwide have from time to time contributed, and may continue to contribute, to slowdowns in the information technology industry, resulting in reduced demand for our solutions as a result of continued constraints on IT-related capital spending by our customers and increased price competition for our solutions. Moreover, we target some of our solutions to the financial services industry and therefore if there is consolidation in that industry, or layoffs, or lack of funding for IT purchases, our business may suffer. If economic conditions deteriorate, our business, financial condition and operating results could be materially and adversely affected.

~~Our business is subject to the risks of earthquakes, fire, power outages, floods and other catastrophic events, and to interruption by manmade problems such as terrorism.~~

Natural disasters or other catastrophic events may cause damage or disruption to our operations, international commerce and the global economy, and thus could have a strong negative effect on us. We have significant operations in the Silicon Valley area of Northern California, a region known for seismic activity. A major earthquake or other natural disaster, fire, act of terrorism or other catastrophic event that results in the destruction or disruption of any of our critical business operations or information technology systems could severely affect our ability to conduct normal business operations and, as a result, our future operating results could be harmed. These negative events could make it difficult or impossible for us to deliver our services to our customers, and could decrease demand for our services. Because we do not carry earthquake insurance for direct quake‑related losses, and significant recovery time could be required to resume operations, our financial condition and operating results could be materially adversely affected in the event of a major earthquake or catastrophic event.

A portion of our revenue is generated by sales to government entities, which are subject to a number of challenges and risks.

Sales to U.S. and foreign federal, state and local governmental agency customers have accounted for a portion of our revenue in past periods, and we may in the future increase sales to government entities. Sales into government entities are subject to a number of risks. Selling to government entities can be highly competitive, expensive and time consuming, often requiring significant upfront time and expense without any assurance that we will win a sale. We have invested in the creation of a cloud offering that has been certified under both the Federal Information Security Management Act and the Federal Risk and Authorization Management Program for government usage but we cannot be sure that we will continue to sustain or renew this certification, that the government will continue to mandate such certification or that other government agencies or entities will use this cloud offering. Government demand and payment for our solutions may be impacted by public sector budgetary cycles and funding authorizations, with funding reductions or delays adversely affecting public sector demand for our solutions. Government entities may have contractual or other legal rights to terminate contracts with our distributors and resellers for convenience or due to a default, and any such termination may adversely impact our future results of operations. For example, if the distributor receives a significant portion of its revenue from sales to such governmental entity, the financial health of the distributor could be substantially harmed, which could negatively affect our future sales to such distributor. Governments routinely investigate and audit government contractors’ administrative processes, and any unfavorable audit could result in the government refusing to continue buying our solutions, a reduction of revenue or fines or civil or

criminal liability if the audit uncovers improper or illegal activities. Any such penalties could adversely impact our results of operations in a material way.

If we fail to maintain an effective system of internal controls, our ability to produce timely and accurate financial statements or comply with applicable regulations could be impaired.

As a public company, we are subject to the reporting requirements of the Exchange Act, the Sarbanes‑Oxley Act of 2002 (the “Sarbanes-Oxley Act”), and the rules and regulations of the ~~NASDAQ~~Nasdaq Global Select Market. We expect that the requirements of these rules and regulations will continue to increase our legal, accounting and financial compliance costs, make some activities more difficult, time consuming and costly, and place significant strain on our personnel, systems and resources.

The Sarbanes-Oxley Act requires, among other things, that we maintain effective disclosure controls and procedures and internal control over financial reporting. We are continuing to develop and refine our disclosure controls and other procedures that are designed to ensure that information required to be disclosed by us in the reports that we file with the SEC, is recorded, processed, summarized and reported within the time periods specified in SEC rules and forms, and that information required to be disclosed in reports under the Exchange Act is accumulated and communicated to our principal executive and financial officers.

Our current controls and any new controls that we develop may become inadequate because of changes in conditions in our business. In addition, because we have acquired companies in the past and may continue to do so in the future, we will also need to expend resources to integrate the controls of these acquired entities with ours. Further, weaknesses in our internal controls may be discovered in the future. Any failure to develop or maintain effective controls, or any difficulties encountered in their implementation or improvement, could harm our operating results or cause us to fail to meet our reporting obligations and may result in a restatement of our financial statements for prior periods. Any failure to implement and maintain effective internal controls also could adversely affect the results of periodic management evaluations and annual independent registered public accounting firm report regarding the effectiveness of our internal control over financial reporting that we are required to include in our Annual Report on Form 10-K under Section 404 of the Sarbanes‑Oxley Act. Ineffective disclosure controls and procedures and internal control over financial reporting could also cause investors to lose confidence in our reported financial and other information, which would likely have a negative effect on the trading price of our common stock.

In order to maintain and improve the effectiveness of our disclosure controls and procedures and internal control over financial reporting, we have expended, and anticipate that we will continue to expend, significant resources, including accounting‑related costs, and provide significant management oversight. Any failure to maintain the adequacy of our internal controls, or consequent inability to produce accurate financial statements on a timely basis, could increase our operating costs and could materially impair our ability to operate our business. In the event that we or our independent registered public accounting firm are not able to complete the work required under Section 404 of the Sarbanes-Oxley Act on a timely basis, or we are not able to demonstrate compliance with Section 404, we could be subject to late filings of our annual and quarterly reports, restatements of consolidated financial statements or other corrective disclosure, and, investors may lose confidence in our operating results and our stock price could decline. In addition, if we are unable to continue to meet these requirements, we may not be able to remain listed on the ~~NASDAQ~~Nasdaq Global Select Market.

We may not be able to utilize a significant portion of our net operating loss or research tax credit carryforwards, which could adversely affect our profitability.

As of December 31, ~~2019,~~2020, we had federal and state net operating loss carryforwards due to prior period losses, some of which if not utilized will continue to expire in ~~2020~~2021 for federal and state purposes. We also have federal research tax credit carryforwards, which will continue to expire in ~~2020.~~2021. These net operating loss and research tax credit carryforwards could expire unused and be unavailable to offset future income tax liabilities, which could adversely affect our profitability.

In addition, under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, our ability to utilize net operating loss carryforwards or other tax attributes, such as research tax credits, in any taxable year may be limited if we experience an “ownership change.” An “ownership change” generally occurs if one or more stockholders or groups of stockholders who own at least 5% of our stock increase their ownership by more than 50 percentage points over their lowest ownership percentage within a rolling three-year period. Similar rules may apply under state tax laws.

Future issuances of our stock could cause an “ownership change.” It is possible that any future ownership change could have a material effect on the use of our net operating loss carryforwards or other tax attributes, which could adversely affect our profitability.

In August 2019, we completed an offering of $920.0 million aggregate principal amount of 0.25% Convertible Senior Notes due 2024 (the “2024 Notes”). As a result of this convertible notes offering, we incurred $920.0 million principal amount of indebtedness, the principal amount of which we may be required to pay at maturity in 2024, upon an event of default (as defined in the indenture governing the 2024 Notes (the “indenture”)), or upon the occurrence of a make-whole fundamental change (as defined in the indenture). There can be no assurance that we will be able to repay this indebtedness when due, or that we will be able to refinance this indebtedness on acceptable terms or at all. In addition, this indebtedness could, among other things:

Conversion of our 2024 Notes may affect the price of our common stock and the value of the 2024 Notes.

The conversion of some or all of our 2024 Notes may dilute the ownership interest of existing stockholders to the extent we deliver shares of common stock upon conversion. Holders of the 2024 Notes will be able to convert them only upon the satisfaction of certain conditions prior to April 15, 2024. Upon conversion, holders of the 2024 Notes will receive cash, shares of common stock or a combination of cash and shares of common stock, at our election. Any sales in the public market of shares of common stock issued upon conversion of the 2024 Notes could adversely affect the trading price of our common stock and the value of the 2024 Notes.

Servicing our debt will require a significant amount of cash. We may not have sufficient cash flow from our business to pay our substantial debt, and we may not have the ability to raise the funds necessary to settle conversions of the 2024 Notes in cash or to repurchase the 2024 Notes upon a fundamental change, which could adversely affect our business and results of operations.

Our ability to make scheduled payments of the principal of, to pay interest on, or to refinance our indebtedness, including the amounts payable under the 2024 Notes, depends on our future performance, which is subject to economic, financial, competitive, and other factors beyond our control. Our business may not continue to generate cash flow from operations in the future sufficient to service our indebtedness and make necessary capital expenditures. If we are unable to generate such cash flow, we may be required to adopt one or more alternatives, such as selling assets, restructuring debt, or obtaining additional equity capital on terms that may be onerous or highly dilutive. Our ability to refinance our indebtedness will depend on the capital markets and our financial condition at such time. We may not be able to engage in any of these activities or engage in these activities on desirable terms, which could result in a default on our debt obligations.

Further, holders of the 2024 Notes have the right to require us to repurchase all or a portion of their 2024 Notes upon the occurrence of a “fundamental change” (as defined in the indenture) before the maturity date at a repurchase price equal to 100% of the principal amount of the 2024 Notes to be repurchased, plus accrued and unpaid interest, if any. In addition, upon conversion of the 2024 Notes, unless we elect to deliver solely shares of our common stock to settle such conversion (other than paying cash in lieu of delivering any fractional share), we will be required to make cash payments in respect toof the 2024 Notes being converted. However,

we may not have enough available cash or be able to obtain financing at the time we are required to make repurchases of 2024 Notes surrendered therefor, or pay cash with respect toof 2024 Notes being converted.

The conditional conversion feature of the 2024 Notes, when triggered, may adversely affect our financial condition and operating results.

In the event the conditional conversion feature of the 2024 Notes is triggered, holders of the 2024 Notes will be entitled to convert their 2024 Notes at any time during specified periods at their option. If one or more holders elect to convert their 2024 Notes, unless we elect to satisfy our conversion obligation by delivering solely shares of our common stock (other than paying cash in lieu of delivering any fractional share), we would be required to settle a portion or all of our conversion obligation in cash, which could adversely affect our liquidity. In addition, even if holders of 2024 Notes do not elect to convert their 2024 Notes, we could be required under applicable accounting rules to reclassify all or a portion of the outstanding principal of the 2024 Notes as a current rather than long-term liability, which would result in a material reduction of our net working capital.

The accounting for convertible debt securities that may be settled in cash, such as the 2024 Notes, could have a material effect on our reported financial results.

Under Accounting Standards Codification 470-20, Debt with Conversion and Other Options (“ASC 470-20”), an entity must separately account for the liability and equity components of the convertible debt instruments (such as the 2024 Notes) that may be

settled entirely or partially in cash upon conversion in a manner that reflects the issuer’s economic interest cost. The effect of ASC 470-20 on the accounting for the 2024 Notes is that the equity component is required to be included in the additional paid-in capital section of stockholders’ equity on our consolidated balance sheet at the issuance date and the value of the equity component ~~would be~~is treated as debt discount for purposes of accounting for the debt component of the 2024 Notes. As a result, we ~~will be~~are required to record a greater amount of ~~noncash~~non-cash interest expense as a result of the amortization of the discounted carrying value of the 2024 Notes to their face amount over the term of the 2024 Notes. We ~~will~~ report larger net losses (or lower net income) in our financial results because ASC 470-20 ~~will require~~requires interest to include both the amortization of the debt discount and the instrument’s non-convertible coupon interest rate, which could adversely affect ~~our reported or future financial results,~~ the trading price of our common stock and the trading price of the 2024 Notes.

The capped call transactions may affect the value of the 2024 Notes and our common stock.

In connection with the pricing of the 2024 Notes, we entered into capped call transactions with certain financial institutions. The capped call transactions are expected generally to reduce or offset the potential dilution upon conversion of the 2024 Notes and/or offset any cash payments we are required to make in excess of the principal amount of converted 2024 Notes, as the case may be, with such reduction and/or offset subject to a cap.

In connection with establishing their initial hedges of the capped call transactions, these financial institutions or their respective affiliates likely purchased shares of our common stock and/or entered into various derivative transactions with respect to our common stock concurrently with or shortly after the pricing of the 2024 Notes. These financial institutions or their respective affiliates may modify their hedge positions by entering into or unwinding various derivatives with respect to our common stock and/or purchasing or selling our common stock or other securities of ours in secondary market transactions following the pricing of the 2024 Notes and prior to the maturity of the 2024 Notes (and are likely to do so during any observation period related to a conversion of 2024 Notes). This activity could also cause or avoid an increase or a decrease in the market price of our common stock or the 2024 Notes.

The potential effect, if any, of these transactions and activities on the price of our common stock or the 2024 Notes will depend in part on market conditions and cannot be ascertained at this time. Any of these activities could adversely affect the value of our common stock.

We are subject to counterparty risk with respect to the capped call transactions.

The counterparties to the capped call transactions we entered into in connection with our 2024 Notes are financial institutions, and we will be subject to the risk that one or more of these counterparties may default or otherwise fail to perform, or may exercise certain rights to terminate, their obligations under the capped call agreements. Our exposure to the credit risk of these counterparties will not be secured by any collateral.

If any of these counterparties to one or more of the capped call transactions becomes subject to insolvency proceedings, we will become an unsecured creditor in those proceedings with a claim equal to our exposure at the time under such transaction. Our exposure will depend on many factors but, generally, our exposure will increase if the market price or the volatility of our common stock increases. In addition, upon a default or other failure to perform, or a termination of obligations, by a counterparty, we may suffer less relief from dilution than we currently anticipate with respect to our common stock. We can provide no assurances as to the financial stability or viability of these counterparties.

Our stock price has been volatile in the past and may be subject to volatility in the future.

The trading price of our common stock has been volatile historically, and is likely to continue to be subject to wide fluctuations in response to various factors described below. Factors affecting the market price of our securities include:

In addition, the stock markets in general and the ~~NASDAQ~~Nasdaq Global Select Market in particular, have experienced substantial price and volume volatility that is often seemingly unrelated to the operating results of any particular companies. Moreover, if the market for technology stocks, especially security and cloud computing-related stocks, or the stock market in general experiences uneven investor confidence, the market price of our common stock could decline for reasons unrelated to our business, operating results or financial condition. The market price for our stock might also decline in reaction to events that affect other companies within, or outside, our industry, even if these events do not directly affect us. Some companies that have experienced volatility in the trading price of their stock have been subject of securities litigation. If we are the subject of such litigation, it could result in substantial costs and a diversion of management’s attention and resources. Furthermore, market volatility arising from the COVID-19 pandemic may lead to increased shareholder activism if we experience a market valuation that they believe is not reflective of our intrinsic value. Activist campaigns that contest or conflict with our strategic direction or seek changes in the composition of our board of directors could have an adverse effect on our operating results and financial condition.

Share repurchases under our Repurchase Program could increase the volatility of the trading price of our common stock, could diminish our cash reserves, could occur at non-optimal prices and may not result in the most effective use of our capital.

On August 27, 2020, our board of directors approved a share repurchase program under which the Company is authorized to repurchase up to $300.0 million of its common stock. As of December 31, 2020, $160.6 million remained available for future share repurchases under the Repurchase Program. Share repurchases under the Repurchase Program could affect the price of our common stock, increase stock price volatility and diminish our cash reserves. In addition, an announcement of the reduction, suspension or termination of the Repurchase Program could result in a decrease in the trading price of our common stock. Moreover, our stock price could decline, resulting in repurchases made at non-optimal prices. Our failure to repurchase our stock at optimal prices may be perceived by investors as an inefficient use of our cash and cash equivalents, which could result in litigation that may have an adverse effect on our business, operating results and financial condition. In addition, while our board of directors carefully considers various alternative uses of our cash and cash equivalents in determining whether to authorize stock repurchases, there can be no assurance that the decision by our board of directors to repurchase stock would result in the most effective uses of our cash and cash equivalents, and there may be alternative uses of our cash and cash equivalents that would be more effective, such as investing in growing our business organically or through acquisitions.

Anti-takeover provisions contained in our certificate of incorporation and bylaws, as well as provisions of Delaware law, and provisions in the indenture for our 2024 Notes, could impair a takeover attempt.

Our certificate of incorporation and bylaws contain provisions that could have the effect of rendering more difficult, delaying or preventing an acquisition of our company deemed undesirable by our board of directors. These provisions could also reduce the price that investors might be willing to pay in the future for shares of our common stock and result in the market price of our common stock being lower than it would be without these provisions. Our corporate governance documents include provisions:

In addition, if a fundamental change occurs prior to the maturity date of the 2024 Notes, holders of the 2024 Notes will have the right, at their option, to require us to repurchase all or a portion of their 2024 Notes. If a “make-whole fundamental change” (as defined in the indenture) occurs prior to the maturity date, we will in some cases be required to increase the conversion rate of the 2024 Notes for a holder that elects to convert its 2024 Notes in connection with such make-whole fundamental change. Furthermore, the indenture prohibits us from engaging in certain mergers or acquisitions unless, among other things, the surviving entity assumes our obligations under the 2024 Notes.

These provisions, alone or together, could frustrate, delay or prevent hostile takeovers and changes in control or changes in our management.

As a Delaware corporation, we are also subject to provisions of Delaware law, including Section 203 of the Delaware General Corporation law, which prevents some stockholders holding more than 15% of our outstanding common stock from engaging in certain business combinations merging or combining with us without approval of the holders of a substantial majority of all of our outstanding common stock.

Our failure to raise additional capital or generate the significant capital necessary to expand our operations and invest in new solutions could reduce our ability to compete and could harm our business.

We may need to raise additional funds, and we may not be able to obtain additional debt or equity financing on favorable terms, if at all. If we raise additional equity financing, our stockholders may experience significant dilution of their ownership interests and the per share value of our common stock could decline. If we issue equity securities in any additional financing, the new securities may have rights and preferences senior to our common stock. If we engage in debt financing, we may be required to accept terms that restrict our ability to incur additional indebtedness and force us to maintain specified liquidity or other ratios. The trading prices for our common stock and the stock of other technology companies have been highly volatile as a result of the COVID-19 pandemic, which may reduce our ability to access capital on favorable terms or at all. In addition, a recession, depression or other sustained adverse market event resulting from the spread of COVID-19 could materially and adversely affect our business and the value of our common stock. If we need additional capital and cannot raise it on acceptable terms, we may not be able to, among other things:

Future sales of our common stock in the public market could lower the market price for our common stock and adversely impact the trading price of our common stock.

In the future, we may sell additional shares of our common stock to raise capital. In addition, a substantial number of shares of our common stock is reserved for issuance upon the conversion of the 2024 Notes, exercise of stock options, the vesting of restricted stock units and restricted stock pursuant to our employee benefit plans, and for purchase by employees under our employee stock purchase plan. We cannot predict the size of future issuances or the effect, if any, that they may have on the market price for our common stock. The issuance and sale of substantial amounts of common stock, or the perception that such issuances and sales may occur, could adversely affect the market price of our common stock and impair our ability to raise capital through the sale of additional equity securities.

We do not anticipate paying cash dividends, and accordingly, stockholders must rely on stock appreciation for any return on their investment.

We do not anticipate paying cash dividends on our common stock in the future. As a result, only appreciation of the price of our common stock will provide a return to our stockholders. Investors seeking cash dividends should not invest in our common stock.

If we are required to collect sales and use taxes on the solutions we sell, we may be subject to liability for past sales and our future sales may decrease.

Our business is subject to the risks of earthquakes, fire, power outages, floods and other catastrophic events, and to interruption by manmade problems such as terrorism.

Natural disasters or other catastrophic events may cause damage or disruption to our operations, international commerce and the global economy, and thus could have a strong negative effect on us. We have significant operations in the Silicon Valley area of Northern California, a region known for seismic activity and wildfires. A major earthquake, wildfire or other natural disaster, fire, act of terrorism or other catastrophic event that results in the destruction or disruption of any of our critical business operations or information technology systems could severely affect our ability to conduct normal business operations and, as a result, our future operating results could be harmed. These negative events could make it difficult or impossible for us to deliver our services to our customers, and could decrease demand for our services. Because we do not carry earthquake insurance for direct quake‑related losses, and significant recovery time could be required to resume operations, our financial condition and operating results could be materially adversely affected in the event of a major earthquake or catastrophic event.

~~Our~~In November 2020, we relocated our corporate headquarters from 892 Ross Drive, Sunnyvale, California to 925 West Maude Avenue, Sunnyvale, California. Our new corporate headquarters at 925 West Maude Avenue, which includes our operations and research and development facilities, ~~is located in Sunnyvale, California, and currently~~ consists of ~~95,557~~approximately 242,400 square feet of space under a lease that expires in ~~2020,~~2031, with ~~a five-year extension option, and 43,925 square feet space under a lease that expires in 2024, with a five-year extension option.~~

In October 2018, we entered into a lease agreement to lease approximately 242,400 square feet of corporate office space in Sunnyvale, California, which is expected to become our new corporate headquarters beginning in 2020. The property will be constructed by the landlord, with the completion date expected to occur between August and November 2020. The lease has a term of 127 months and a five-year extension option.

We lease additional U.S. offices in California, Utah, Pennsylvania, ~~Texas,~~ Massachusetts, Indiana and Colorado. We also lease offices in Canada, France, Japan, ~~Germany,~~ the United Kingdom, ~~Ireland,~~ Australia, Dubai and Israel. We believe our facilities are adequate for our current needs and for the foreseeable future.

We operate ~~sixteen~~fifteen data centers at third-party facilities throughout the world: ~~ten~~nine in the United States, two in Canada, one in the Netherlands, one in France, one in Germany and one in Australia.

From time to time, we may be involved in legal proceedings and subject to claims in the ordinary course of business.

Although the results of these proceedings and claims cannot be predicted with certainty, we do not believe the ultimate cost to resolve these matters would individually, or taken together, have a material adverse effect on our business, operating results, cash flows or financial condition. Regardless of the outcome, such proceedings can have an adverse impact on us because of defense and settlement costs, diversion of resources and other factors, and there can be no assurances that favorable outcomes will be obtained.

ITEM 5. MARKET FOR REGISTRANT’S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES

Our common stock is traded on the ~~NASDAQ~~Nasdaq Global Select Market, under the symbol PFPT.

As of February ~~7, 2020,~~5, 2021, there were 3132 stockholders of record, although we believe that there are a larger number of beneficial owners as many of our shares of our common stock are held by brokers and other institutions on behalf of stockholders.

We have never declared or paid any cash dividends on our common stock. We currently intend to retain any future earnings and do not expect to pay any cash dividends on our common stock for the foreseeable future. Any determination to pay dividends in the future will be at the discretion of our board of directors and will be dependent on a number of factors, including our earnings, capital requirements and overall financial conditions.

On August 27, 2020, the board of directors approved a share repurchase program under which the Company is authorized to repurchase up to $300.0 million of its common stock. The Repurchase Program does not have an expiration date. Below is a summary of our common share repurchased during the three months ended December 31, 2020. See Note 11 to our consolidated financial statements for information regarding our Repurchase Program.

The following graph shows a comparison of the five years ended December 31, ~~2019,~~2020, of the cumulative total return for our common stock, the ~~NASDAQ~~Nasdaq Composite Index, and the ~~NASDAQ~~Nasdaq Computer Index. The graph assumes an investment of $100 on December 31, ~~2014~~2015 and reinvestment of any dividends. The comparisons in the graph below are required by the Securities and Exchange Commission and are not intended to forecast or be indicative of possible future performance of our common shares.

The above stock Performance Graph and related information shall not be deemed “filed” with the SEC and is not to be incorporated by reference into any filing of Proofpoint, Inc. made under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended.

The following tables present selected historical financial data for our business. You should read this information together with “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and the consolidated financial statements, related notes and other financial information included elsewhere in this Annual Report on Form 10-K. The selected consolidated financial data in this section are not intended to replace the consolidated financial statements and are qualified in their entirety by the consolidated financial statements and related notes included elsewhere in this Annual Report on Form 10-K.

We derived the consolidated statements of operations data for the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, and the consolidated balance sheet data as of December 31, ~~2019~~2020 and ~~2018~~2019 from our audited consolidated financial statements included elsewhere in this report. We derived the consolidated statements of operations data for the years ended December 31, ~~2016~~2017 and ~~2015~~2016 and the consolidated balance sheet data as of December 31, 2018, 2017 ~~2016~~ and ~~2015~~2016 from our consolidated financial statements not included in this report. Our historical results are not necessarily indicative of the results to be expected in the future.

																Year Ended December 31,
	Years Ended December 31,															2020			2019			2018			2017 (a)			2016 (a)
	2019			2018			2017 (a)			2016 (a)			2015
	(in thousands, except per share data)															(in thousands, except per share data)
Consolidated Statements of Operations Data:
Revenue:
Subscription	$	875,006		$	704,400		$	506,355		$	367,494		$	257,329		$	1,031,045		$	875,006		$	704,400		$	506,355		$	367,494
Hardware and services		13,184			12,594			13,326			10,843			8,068			18,965			13,184			12,594			13,326			10,843
Total revenue		888,190			716,994			519,681			378,337			265,397			1,050,010			888,190			716,994			519,681			378,337
Cost of revenue:(1)
Subscription		206,997			180,253			125,832			94,716			71,746			240,615			206,997			180,253			125,832			94,716
Hardware and services		29,217			21,508			17,546			13,877			12,312			34,844			29,217			21,508			17,546			13,877
Total cost of revenue		236,214			201,761			143,378			108,593			84,058			275,459			236,214			201,761			143,378			108,593
Gross profit		651,976			515,233			376,303			269,744			181,339			774,551			651,976			515,233			376,303			269,744
Operating expense:(1)
Research and development		230,463			185,391			129,803			98,506			74,459			283,799			230,463			185,391			129,803			98,506
Sales and marketing		416,717			345,368			248,694			189,324			148,414			488,235			416,717			345,368			248,694			189,324
General and administrative		109,727			86,185			52,735			52,774			36,616			97,713			109,727			86,185			52,735			52,774
Total operating expense		756,907			616,944			431,232			340,604			259,489			869,747			756,907			616,944			431,232			340,604
Operating loss		(104,931	)		(101,711	)		(54,929	)		(70,860	)		(78,150	)		(95,196	)		(104,931	)		(101,711	)		(54,929	)		(70,860	)
Interest expense (b)		(12,526	)		(16,761	)		(28,608	)		(25,082	)		(18,374	)
Other income (expense), net		7,109			1,491			3,785			441			(1,553	)
Interest expense																	(36,241	)		(12,526	)		(16,761	)		(28,608	)		(25,082	)
Other income, net																	548			7,109			1,491			3,785			441
Loss before income taxes		(110,348	)		(116,981	)		(79,752	)		(95,501	)		(98,077	)		(130,889	)		(110,348	)		(116,981	)		(79,752	)		(95,501	)
(Provision for) benefit from income taxes		(19,917	)		13,232			9,950			(986	)		(635	)		(32,920	)		(19,917	)		13,232			9,950			(986	)
Net loss	$	(130,265	)	$	(103,749	)	$	(69,802	)	$	(96,487	)	$	(98,712	)	$	(163,809	)	$	(130,265	)	$	(103,749	)	$	(69,802	)	$	(96,487	)
Net loss per share, basic and diluted	$	(2.33	)	$	(1.99	)	$	(1.58	)	$	(2.31	)	$	(2.48	)	$	(2.86	)	$	(2.33	)	$	(1.99	)	$	(1.58	)	$	(2.31	)
Weighted average shares outstanding, basic and diluted		55,902			52,111			44,258			41,859			39,787			57,324			55,902			52,111			44,258			41,859

											As of December 31,
	As of December 31,										2020		2019		2018		2017 (a)		2016 (a)
	2019		2018		2017 (a)		2016 (a)		2015
	(in thousands)										(in thousands)
Consolidated Balance Sheet Data:
Cash, cash equivalents and short-term investments	$	890,940	$	231,699	$	331,598	$	396,751	$	406,237	$	910,279	$	890,940	$	231,699	$	331,598	$	396,751
Deferred commissions, current and long-term	$	137,555	$	107,380	$	78,203	$	60,768	$	22,802	$	166,541	$	137,555	$	107,380	$	78,203	$	60,768
Property and equipment, net	$	73,512	$	70,627	$	73,617	$	52,523	$	34,501	$	111,030	$	73,512	$	70,627	$	73,617	$	52,523
Total assets	$	2,337,511	$	1,233,018	$	1,018,432	$	836,929	$	705,616	$	2,498,710	$	2,337,511	$	1,233,018	$	1,018,432	$	836,929
Convertible senior notes	$	749,620	$	—	$	197,858	$	366,541	$	345,699	$	783,561	$	749,620	$	—	$	197,858	$	366,541
Other debt, current and long-term	$	—	$	—	$	89	$	123	$	155	$	—	$	—	$	—	$	89	$	123
Deferred revenue, current and long-term	$	784,063	$	598,130	$	427,829	$	295,015	$	223,726	$	892,280	$	784,063	$	598,130	$	427,829	$	295,015
Total stockholders’ equity	$	592,497	$	512,534	$	299,115	$	96,379	$	83,185	$	441,744	$	592,497	$	512,534	$	299,115	$	96,379

ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with our “Selected Consolidated Financial Data” and our consolidated financial statements and related notes included elsewhere in this Annual Report on Form 10-K. This discussion contains forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those forward-looking statements below. Factors that could cause or contribute to those differences include, but are not limited to, those identified below and those discussed in the section entitled “Risk Factors” included elsewhere in this Annual Report on Form 10-K. This Annual Report on Form 10-K contains “forward-looking statements” within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). These statements are often identified by the use of words such as “may,” “will,” “expect,” “believe,” “anticipate,” “intend,” “could,” “estimate,” or “continue,” and similar expressions or variations. Such forward-looking statements are subject to risks and uncertainties, including risk and uncertainty around the impact of the COVID-19 outbreak, and other factors that could cause actual results and the timing of certain events to differ materially from future results expressed or implied by such forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those identified herein, and those discussed in the section titled “Risk Factors”, set forth in Part I, Item 1A of this Form 10-K. Except as required by law, we disclaim any obligation to update any forward-looking statements to reflect events or circumstances after the date of such statements.

Proofpoint is a leading next generation cybersecurity company that enables large and mid-sized organizations worldwide to protect their employees from advanced threats and compliance risks. Our security and compliance platform is comprised of an integrated suite of advanced threat protection, information protection, and brand protection solutions. These capabilities include email protection and authentication, advanced threat protection, data loss prevention, email encryption, SaaS application protection, response orchestration and automation, digital risk, security training, web browser isolation, archiving, eDiscovery, supervision, and secure communication. Our solutions are built on a flexible, cloud-based platform and leverage a number of proprietary technologies - including big data analytics, machine learning, deep content inspection, secure storage, advanced encryption, intelligent message routing, dynamic malware analysis, threat correlation, and virtual execution environments to address today’s rapidly changing threat and compliance landscape.

Our platform addresses this growing challenge by not only protecting data as it flows into and out of the enterprise via on-premises and cloud-based email, social media and other cloud applications, but also by keeping track of this information as it is modified and distributed throughout the enterprise for compliance and data loss prevention, and securely archiving these communications for compliance and discovery. We help organizations reduce their critical risk in five major ways:

We were founded in 2002 to provide a unified solution to help enterprises address their growing data security requirements. Our first solution was commercially released in 2003 to combat the burgeoning problem of spam and viruses and their impact on corporate email systems. To address the evolving threat landscape and the adoption of communication and collaboration systems beyond corporate email and networks, we have broadened our solutions to defend against a wide range of threats, including email, mobile apps and social media, to protect the information people create from both compromise and compliance risks, and to archive and govern corporate information. ~~Today, our solutions are used worldwide to protect well over 100 million end users at enterprise customers, and millions more via service providers through our Cloudmark division.~~ As the threat environment has continued to evolve, we have dedicated significant resources to meet the ongoing challenges that this highly dynamic environment creates for our customers such as investing significantly to expand the breadth of our data protection platform as these expenditures are primarily in connection with the replacement and upgrade of equipment to lower the cost of deployment as well as to improve the efficiency for our cloud-based architecture.

Our business is based on a recurring revenue model. Our customers pay a subscription fee to license the various components of our SaaS platform for a contract term that is typically one to three years. At the end of the license term, customers may renew their subscription and in each year since the launch of our first solution in 2003, we have maintained a renewal rate with our existing customers of ~~over~~ 90%. or higher. We derive this retention rate by calculating the total annually recurring subscription revenue from customers currently using our SaaS platform and dividing it by the total annually recurring subscription revenue from both these current customers as well as all business lost through non-renewal.

We market and sell our solutions worldwide both directly through our sales teams and indirectly through a hybrid model where our sales organization actively assists our network of distributors and resellers. We also derive a lesser portion of our total revenue from the license of our solutions to strategic partners who offer our solutions in conjunction with one or more of their own products or services.

Our solutions are designed to be implemented, configured and operated without the need for any training or professional services. We offer various training and professional services for those customers that seek to develop deeper expertise in the use of our solutions or would like assistance with complex configurations or the importing of data. In some cases, we provide a hardware appliance to those customers that elect to host elements of our solution behind their firewall. Increasing adoption of virtualization in the data center has led to a decline in the sales of our hardware appliances and a shift towards our software-based virtual appliances, which are delivered as a download via the Internet. Our hardware and services offerings carry lower margins and are provided as a courtesy to our customers. We expect the overall proportion of revenue derived from the hardware and services offerings to generally remain below 5% of our total revenue.

Historically, the majority of our revenue was derived from our customers in the United States. We believe the markets outside of the United States offer an opportunity for growth and we intend to make additional investments in sales and marketing to expand in these markets. Revenue from customers outside of the United States grew ~~32%~~25% for the year ended December 31, ~~2019~~2020 as compared to the prior year. In terms of customer concentration, there were two partners who accounted for ~~12%~~13% and 11%, respectively, of our total revenue in ~~2019.~~2020. In ~~2018~~2019, there were two partners who accounted for 12% and ~~2017,~~11%, respectively, of our total revenue. In 2018, one partner accounted for 12% of our total ~~revenue in each year.~~revenue. These partners sold to a number of end users, none of which accounted for more than 10% of our total revenue in 2020, 2019 ~~2018~~ and ~~2017.~~2018. The partners’ sales were spread across many individual customers, all of which have a direct relationship with us as part of their access to our demand services.

We have not been profitable to date and will need to grow revenue at a rate faster than our investments in cost of revenue and operating expenses in order to achieve profitability, as discussed in more detail below.

In March 2020, the World Health Organization declared the outbreak of the COVID-19 pandemic, which continues to spread throughout the U.S. and the world and has resulted in authorities implementing numerous measures to contain the virus, including travel bans and restrictions, quarantines, shelter-in-place orders, and business limitations and shutdowns. The Company’s overall financial results and operations were modestly impacted by the COVID-19 outbreak in 2020. The Company’s travel expense and marketing expense for in-person events were decreased due to global restrictions on travel issued by most major nations where the Company does business. We have shifted our internal annual Sales Kick Off conference, which was held in January 2021, to a virtual-only conference and in the near term we have changed our customer, employee and industry events to virtual-only formats. In addition, see Part II-Item 1A, “Risk Factors,” included herein for an update that we made to our existing risk factors to include information on risks associated with pandemics in general and COVID-19 specifically. The extent to which the COVID-19 outbreak impacts our financial results and operations going forward will depend on future developments which are highly uncertain and cannot be predicted, including new information which may emerge concerning the severity of the outbreak and the actions being taken to contain and treat it.

We are taking a variety of measures to ensure the availability and functioning of our critical infrastructure, to promote the safety and security of our employees and to support the communities in which we operate. These measures include requiring remote working arrangements for employees where practicable. We are following public and private sector policies and initiatives to reduce the transmission of COVID-19, such as the imposition of travel restrictions, the promotion of social distancing and the adoption of work-from-home arrangements, and all of these policies and initiatives could impact our operations. The COVID-19 pandemic presents extraordinary challenges in predicting future performance, and while we have modeled many scenarios and associated outcomes, there may be events or trends that are more dire than we have modeled given the unique nature of this event. In particular, we are monitoring COVID-19’s effects on our business across many dimensions, including its broad effects on customers in highly impacted industries and on key European economies as they each attempt to recover. These dimensions may change as the pandemic and the response to the pandemic evolve. Some of our customers impacted by COVID-19 seek to manage cash by executing shorter contract durations or by furloughing or laying off employees, especially in highly impacted industries such as travel and hospitality. Other customers are choosing to slow or defer projects, especially those in highly impacted industries and with complex projects requiring large archiving imports that rely heavily on third party resources to manage and execute. We will continue to monitor the

impact of the COVID-19 pandemic and continually assess its potential effects on our business and our outlook, the actual results of which will largely depend on future developments, including the duration and spread of the outbreak as well as the varied impacts to our customer base by region or industry, which cannot be accurately predicted and are uncertain.

The total costs associated with the teams tasked with closing business with new customers and additional business with our existing customers have represented more than 90% of our total sales and marketing costs since 2008. Although we expect customers to be profitable over the duration of the customer relationship, the upfront costs typically exceed related revenue during the earlier periods of a contract. As a result, while our practice of invoicing our customers for the entire amount of the contract at the start of the term provides us with a relatively immediate contribution to cash flow, the revenue is recognized ratably over the term of the contract, and hence contributions toward operating income are limited in the period where the sales and marketing costs are incurred. Accordingly, an increase in the mix of new customers as a percentage of total customers would likely negatively impact our near-term operating results. On the other hand, we expect that an increase in the mix of existing customers as a percentage of total customers would positively impact our operating results over time. As we accumulate customers that continue to renew their contracts, we anticipate that our mix of existing customers will increase, contributing to a decrease in our sales and marketing costs as a percentage of total revenue and a commensurate improvement in our operating income.

As part of maintaining our SaaS platform, we provide ongoing updates and enhancements to the platform services both in terms of the software as well as the underlying hardware and data center infrastructure. These updates and enhancements are provided to our customers at no additional charge as part of the subscription fees paid for the use of our platform. While more traditional products eventually become obsolete and require replacement, we are constantly updating and maintaining our cloud-based services and as such they operate with a continuous product life cycle. Much of this work is designed to both maintain and enhance the

customers’ experience over time while also lowering our costs to deliver the service. Our SaaS platform is a shared infrastructure that is used by all of our customers. Accordingly, the costs of the platform are spread in a relatively uniform manner across the entire customer base and no specific infrastructure elements are directly attached to any particular customer. As such, in the event that a customer chooses to not renew its subscription, the underlying resources are reallocated either to new customers or to accommodate the expanding needs of our existing customers and, as a result, we do not believe that the loss of any particular customer has a meaningful impact on our gross profit as long as we continue to grow our customer base.

~~To date,~~Historically our customers have primarily used our cybersecurity and compliance solutions ~~in conjunction~~ with email messaging content. ~~We have developed~~Increasingly, customers are also adopting many of our emerging solutions as part of a people-centric approach to ~~address new~~cybersecurity, which focuses on identifying and ~~evolving messaging solutions~~mitigating risks posed by individual users and the attacks that target them. Our people-centric portfolio includes CASB, Isolation, Insider Threat Management, and Proofpoint Security Awareness Training, many of which provide cyber resiliency across other vectors such as ~~social media~~cloud, web and file sharing applications, but these solutions are relatively nascent. If customers increase their use of these new messaging solutions in the future, we anticipate that our growth in revenue associated with older email messaging solutions may slow over time. Although revenue associated with our social mediaendpoint as well as security awareness training and file sharing applications has not been material to date, we believe that our ability to provide security, archiving, governance and discovery for these new solutions will be viewed as valuable by our existing customers, enabling us to derive revenue from these new forms of messaging and communication.phishing simulation.

With the majority of our business, we invoice our customers for the entire contract amount at the start of the term and these amounts are recorded as deferred revenue on our balance sheet, with the dollar weighted average duration of these contracts for any given period over the past three years typically ranging from 14 to 20 months. As a result, while our practice of invoicing customers for the entire amount of the contract at the start of the term provides us with a relatively immediate contribution to cash flow, the revenue is recognized ratably over the term of the contract, and hence contributions toward operating income are realized over an extended period. As such, our efforts to improve our profitability require us to invest far less in operating expenses than the cash flow generated by our business might otherwise allow. As we strive to invest in an effort to continue to increase the size and scale of our business, we expect that the level of investment afforded by our growth in revenue should be sufficient to fund the investments needed to drive revenue growth and broaden our product line.

Considering all of these factors, we do not expect to be profitable on a GAAP basis in the near term and in order to achieve profitability we will need to grow revenue at a rate faster than our investments in operating expenses and cost of revenue.

We intend to grow our revenue through acquiring new customers by investing in our sales and marketing activities. We believe that an increase in new customers in the near term will result in a larger base of renewal customers, which, over time, we expect to be more profitable for us.

Sales and marketing is our largest expense and hence a significant contributing factor to our operating losses. We believe that our opportunity to improve our return on investment on sales and marketing costs relies primarily on our ongoing ability to cost-effectively renew our business with existing customers, thereby lowering our overall sales and marketing costs as a percentage of revenue as the mix of revenue derived from this more profitable renewal activity increases over time. Therefore, we anticipate that our initial significant investments in sales and marketing activities will, over time, generate a larger base of more profitable customers. Cost of subscription revenue is also a significant expense for us, and we expect to continue to build on the improvements over the past years, such as in replacing third-party technology with our proprietary technology and improving the utilization of our fixed investments in equipment and infrastructure, in order to provide the opportunity for improved subscription gross margins over time.

Although we plan to continue enhancing our solutions, we intend to lower our rate of investment in research and development as a percentage of revenue over time by deriving additional revenue from our existing solutions rather than by adding entirely new categories of solutions. In addition, as personnel costs are one of the primary drivers of the increases in our operating expenses, we plan to reduce our historical rate of headcount growth over time.

We regularly review a number of metrics, including the following key metrics presented in the table below, to evaluate our business, measure our performance, identify trends in our business, prepare financial projections and make strategic decisions. Many of these key metrics, such as non-GAAP gross margin, billings and free cash flow, are non-GAAP measures. This non-GAAP information is not necessarily comparable to non-GAAP information of other companies. Users of this financial information should consider the types of events and transactions for which adjustments have been made.

										Year Ended December 31,
	Year Ended December 31,									2020			2019			2018
	2019			2018			2017
	(in thousands)									(in thousands)
Total revenue	$	888,190		$	716,994		$	519,681		$	1,050,010		$	888,190		$	716,994
Growth		24	%		38	%		37	%		18	%		24	%		38	%
Gross margin percentage		73	%		72	%		72	%		74	%		73	%		72	%
Non-GAAP gross margin		79	%		78	%		78	%		80	%		79	%		78	%
Billings (non-GAAP)	$	1,072,159		$	875,323		$	638,839		$	1,157,341		$	1,072,159		$	875,323
Growth		22	%		37	%		38	%		8	%		22	%		37	%
Free cash flows (non-GAAP)	$	207,315		$	155,222		$	106,728		$	192,068		$	207,315		$	155,222

We define non-GAAP gross margin as non-GAAP gross profit divided by GAAP revenue. We define non-GAAP gross profit as GAAP gross profit, adjusted to exclude stock-based compensation expense and the amortization of intangibles associated with acquisitions. We consider this non-GAAP financial measure to be a useful metric for management and investors because it excludes the effect of stock-based compensation expense and the amortization of intangibles associated with acquisitions so that our management and investors can compare our business operating results over multiple periods, and compare our financial results with other companies in its industry, many of which present similar non-GAAP financial measure. However, there are a number of limitations related to the use of non-GAAP gross margin versus gross margin calculated in accordance with GAAP. For example, stock-based compensation has been and will continue to be for the foreseeable future a significant recurring expense in our business. Stock-based compensation is an important part of our employees’ compensation and impacts their performance. In addition, the components of the costs that we exclude in our calculation of non-GAAP gross margin may differ from the components that our peer companies exclude when they report their non-GAAP results. Management compensates for these limitations by providing specific information regarding the GAAP amounts excluded from non-GAAP gross margin and evaluating non-GAAP gross margin together with gross margin calculated in accordance with GAAP.

The following table presents the reconciliation of gross margin to Non-GAAP gross margin for the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017:~~2018:

										Year Ended December 31,
	Year Ended December 31,									2020			2019			2018
	2019			2018			2017
	(in thousands)									(in thousands)
GAAP gross profit	$	651,976		$	515,233		$	376,303		$	774,551		$	651,976		$	515,233
GAAP gross margin		73	%		72	%		72	%		74	%		73	%		72	%
Plus:
Stock-based compensation expense		20,967			16,299			12,528			26,040			20,967			16,299
Amortization of intangible assets		30,760			26,971			14,512			41,277			30,760			26,971
Non-GAAP gross profit	$	703,703		$	558,503		$	403,343		$	841,868		$	703,703		$	558,503
Non-GAAP gross margin		79	%		78	%		78	%		80	%		79	%		78	%

We have included billings, a non‑GAAP financial measure, in this report because it is a key measure used by our management and board of directors to manage our business and monitor our near term cash flows. We define billings as revenue recognized plus the change in deferred revenue and customer prepayments less unbilled accounts receivable from the beginning to the

end of the period, but excluding additions to deferred revenue and customer prepayments from acquisitions. We have provided reconciliation between total revenue, the most directly comparable GAAP financial measure, and billings. Accordingly, we believe that billings provide useful information to investors and others in understanding and evaluating our operating results in the same manner as our management and board of directors.

Our use of billings as a non-GAAP measure has limitations as an analytical tool, and you should not consider it in isolation or as a substitute for revenue or an analysis of our results as reported under GAAP. Some of these limitations are:

Our deferred revenue consists of amounts that have been invoiced but have not been recognized as revenue as of the period end. Customer prepayments represent billed amounts for which the contract can be terminated and the customer has a right of refund. Unbilled accounts receivable represent amounts for which we have recognized revenue, pursuant to our revenue recognition policy, for subscription software already delivered and professional services already performed, but billed in arrears and for which we believe we have an unconditional right to payment.

The following table presents the reconciliation of total revenue to billings for the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017:~~2018:

										Year Ended December 31,
	Year Ended December 31,									2020		2019			2018
	2019			2018			2017
	(in thousands)									(in thousands)
Total revenue	$	888,190		$	716,994		$	519,681		$	1,050,010	$	888,190		$	716,994
Deferred revenue and customer prepayments
Ending		797,173			605,073			431,371			904,126		797,173			605,073
Beginning		605,073			431,371			295,996			797,173		605,073			431,371
Net change		192,100			173,702			135,375			106,953		192,100			173,702
Unbilled accounts receivable
Ending		2,255			1,276			603			1,877		2,255			1,276
Beginning		1,276			603			486			2,255		1,276			603
Net change		(979	)		(673	)		(117	)		378		(979	)		(673	)
Less: deferred revenue and customer prepayments contributed by acquisitions		(7,152	)		(14,700	)		(16,100	)		—		(7,152	)		(14,700	)
Billings	$	1,072,159		$	875,323		$	638,839		$	1,157,341	$	1,072,159		$	875,323

We define free cash flow as net cash provided by operating activities minus capital expenditures. We consider free cash flow to be a liquidity measure that provides useful information to management and investors about the amount of cash generated by the business that, after the acquisition of property and equipment, can be used for strategic opportunities, including investing in our business, making strategic acquisitions, and strengthening the balance sheet. Analysis of free cash flow facilitates management’s comparisons of our operating results to competitors’ operating results. A limitation of using free cash flow versus the GAAP measure of net cash provided by operating activities as a means for evaluating our company is that free cash flow does not represent the total increase or decrease in the cash balance from operations for the period because it excludes cash used for capital expenditures during the period. Management compensates for this limitation by providing information about our capital expenditures on the face of the cash flow statement and in the “Liquidity and Capital Resources” section below.

										Year Ended December 31,
	Year Ended December 31,									2020			2019			2018
	2019			2018			2017
	(in thousands)									(in thousands)
GAAP cash flows provided by operating activities:	$	242,508		$	184,744		$	153,686		$	264,488		$	242,508		$	184,744
Less:
Purchase of property and equipment		(35,193	)		(29,522	)		(46,958	)		(72,420	)		(35,193	)		(29,522	)
Non-GAAP free cash flows	$	207,315		$	155,222		$	106,728		$	192,068		$	207,315		$	155,222

We derive our revenue primarily through the license of various solutions and services on our security-as-a-service platform on a subscription basis, supplemented by the sales of training, professional services and hardware depending upon our customers’ requirements.

Subscription. We license our platform and its associated solutions and services on a subscription basis. The fees are charged on a per user, per year basis. Subscriptions are typically one to three years in duration. We invoice our customers upon signing for the entire term of the contract. The invoiced non-cancellable amounts billed in advance are treated as deferred revenue on the balance sheet and are recognized ratably, in accordance with the appropriate revenue recognition guidelines, over the term of the contract. We also derive a portion of our subscription revenue from the license of our solutions to strategic partners. We bill these strategic partners monthly. We expect our subscription revenue will continue to grow and remain above 95% of our total revenue.

Hardware and services. We provide hardware appliances as a convenience to our customers and as such it represents a small part of our business. Our solutions are designed to be implemented, configured and operated without the need for any training or professional services. For those customers that seek to develop deeper expertise in the use of our solutions or would like assistance with complex configurations or the importing of data, we offer various training and professional services. We typically invoice the customer for hardware at the time of shipment. We typically invoice customers for services at the time the order is placed and recognize this revenue as the services are performed. On occasion, customers may retain us for special projects such as archiving import and export services; these types of services are recognized upon completion of the project. We expect the overall proportion of revenue derived from hardware and service offerings to generally remain below 5% of our total revenue.

Our cost of revenues consists of cost of subscription revenue and cost of hardware and services revenue. Personnel costs, which consist of salaries, benefits, bonuses, stock-based compensation, data center costs and hardware costs, are the most significant components of our cost of revenues. We expect personnel costs to continue to increase in absolute dollars as we hire new employees to continue to grow our business.

Cost of Subscription Revenue. Cost of subscription revenue primarily includes personnel costs, consisting of salaries, benefits, bonuses, and stock-based compensation, for employees who provide support services to our customers and operate our data centers. Other costs include fees paid to contractors who supplement our support and data center personnel; expenses related to the use of third-party data centers in both the United States and internationally; depreciation of data center equipment; amortization of licensing fees and royalties paid for the use of third-party technology; amortization of internally developed intangible assets; and the amortization of intangible assets acquired through business combinations. Growth in subscription revenue generally consumes production resources, requiring us to gradually increase our cost of subscription revenue in absolute dollars as we expand our investment in data center equipment, the third-party data center space required to house this equipment, and the personnel needed to manage this higher level of activity.

Cost of Hardware and Services Revenue. Cost of hardware and services revenue includes personnel costs for employees who provide training and professional services to our customers as well as the cost of server hardware shipped to our customers that we procure from third parties and configure with our software solutions.

Our operating expenses consist of research and development, sales and marketing, and general and administrative expenses. Personnel costs, which consist of salaries, benefits, bonuses, and stock-based compensation, are the most significant component of our operating expenses. Our headcount has increased from ~~2,047~~2,613 employees as of December 31, ~~2017~~2018 to ~~3,368~~3,658 employees as of December 31, ~~2019.~~2020. As a result of this growth in headcount, operating expenses have increased significantly over these periods. We expect personnel costs to continue to increase in absolute dollars as we hire new employees to continue to grow our business.

Research and Development. Research and development expenses include personnel costs, consulting services and depreciation. We believe that these investments have played an important role in broadening the capabilities of our platform over the course of our operating history, enhancing the relevance of our solutions in the market in general and helping us to retain our customers over time. We expect to continue to devote substantial resources to research and development in an effort to continuously improve our existing solutions as well as to develop new offerings. We believe that these investments are necessary to maintain and improve our competitive position. However, over the longer term, we intend to monitor these costs so as to decrease this spending as a percentage of total revenue. Our research efforts include both software developed for our internal use on behalf of our customers as well as software elements to be used by our customers in their own facilities. To date, our capitalized costs on software developed for internal use on behalf of our customers were not material. For the software developed for use on our customers’ premises, the costs associated with the development work between technological feasibility and the general availability has not been material and as such we have not capitalized any of these development costs to date.

Sales and Marketing. Sales and marketing expenses include personnel costs, sales commissions, and other costs including travel and entertainment, marketing and promotional events, public relations and marketing activities. These costs also include amortization of intangible assets as a result of our past acquisitions. Due to our continued investment in growing our sales and marketing operations, both domestically and internationally, headcount increases were reflected in higher compensation expense consistent with our revenue growth. Our sales personnel are typically not immediately productive, and therefore the increase in sales and marketing expenses we incur when we add new sales representatives is not immediately offset by increased revenue and may not result in increased revenue over the long-term if these new sales people fail to become productive. The timing of our hiring of new sales personnel and the rate at which they generate incremental revenue will affect our future financial performance. We expect that sales and marketing expenses will continue to increase in absolute dollars and be among the most significant components of our operating expenses.

General and Administrative. General and administrative expenses consist of personnel costs, consulting services, audit fees, tax services, legal expenses and other general corporate items. As a result of our operational growth, we expect our general and administrative expenses to increase in absolute dollars in future periods as we continue to expand our operations and hire additional personnel.

Interest expense consists of interest expense and loss on conversion related to our convertible senior notes.

Other income, net, consists primarily of interest income earned on our cash, cash equivalents and short-term investments, and the net effect of foreign currency transaction gains and losses.

For most of the prior years, our income tax expense or benefit were primarily related to state and foreign income taxes. As we have incurred operating losses in all periods to date and recorded a full valuation allowance against our deferred tax assets, we had not historically recorded a provision for federal income taxes. However, in the year ended December 31, 2017, we recognized $0.2 million of deferred tax benefit in the U.S. related to amortization of tax goodwill on business acquisitions and $12.3 million of deferred tax benefit in the U.S. related to changes in the Company’s valuation allowance resulting from the Cloudmark, Inc. and WebLife Balance, Inc. business acquisitions. For the year ended December 31, 2018, we recognized $14.7 million of deferred tax benefit in the U.S. related to changes in the Company’s valuation allowance resulting from the Wombat Security Technologies, Inc. acquisition. For the year ended December 31, 2019, we recognized $0.3 million of deferred tax benefit in the U.S. related to amortization of tax goodwill on certain business acquisitions. For the year ended December 31, 2020, we recognized $0.2 million of deferred tax expense in the U.S. related to amortization of tax goodwill on certain business acquisitions. Realization of any of our deferred tax assets depends upon future earnings, the timing and amount of which are uncertain. Utilization of our net operating losses and research and development credits may be subject to substantial annual limitation due to the ownership change limitations provided by the Internal Revenue Code and similar state provisions. Analyses have been conducted to determine whether an ownership change had occurred since inception. The analyses have indicated that although ownership changes have occurred in prior years, the net operating losses and research and development credits would not expire before utilization as a result of the ownership change. In the event we have subsequent changes in ownership, net operating losses and research and development credit carryovers could be limited and may expire unutilized as a result of the subsequent ownership change.

										Year Ended December 31,
	Year Ended December 31,									2020			2019			2018
	2019			2018			2017
	(in thousands)									(in thousands)
Revenue:
Subscription	$	875,006		$	704,400		$	506,355		$	1,031,045		$	875,006		$	704,400
Hardware and services		13,184			12,594			13,326			18,965			13,184			12,594
Total revenue		888,190			716,994			519,681			1,050,010			888,190			716,994
Cost of revenue:(1)
Subscription		206,997			180,253			125,832			240,615			206,997			180,253
Hardware and services		29,217			21,508			17,546			34,844			29,217			21,508
Total cost of revenue		236,214			201,761			143,378			275,459			236,214			201,761
Gross profit		651,976			515,233			376,303			774,551			651,976			515,233
Operating expense:(1)
Research and development		230,463			185,391			129,803			283,799			230,463			185,391
Sales and marketing		416,717			345,368			248,694			488,235			416,717			345,368
General and administrative		109,727			86,185			52,735			97,713			109,727			86,185
Total operating expense		756,907			616,944			431,232			869,747			756,907			616,944
Operating loss		(104,931	)		(101,711	)		(54,929	)		(95,196	)		(104,931	)		(101,711	)
Interest expense		(12,526	)		(16,761	)		(28,608	)		(36,241	)		(12,526	)		(16,761	)
Other income, net		7,109			1,491			3,785			548			7,109			1,491
Loss before income taxes		(110,348	)		(116,981	)		(79,752	)		(130,889	)		(110,348	)		(116,981	)
(Provision for) benefit from, income taxes		(19,917	)		13,232			9,950			(32,920	)		(19,917	)		13,232
Net loss	$	(130,265	)	$	(103,749	)	$	(69,802	)	$	(163,809	)	$	(130,265	)	$	(103,749	)

The following table sets forth our consolidated results of operations for the specified periods as a percentage of our total revenue for those periods.

	Year Ended December 31,									Year Ended December 31,
	2019			2018			2017			2020			2019			2018
Revenue:
Subscription		99	%		98	%		97	%		98	%		99	%		98	%
Hardware and services		1			2			3			2			1			2
Total revenue		100			100			100			100			100			100
Cost of revenue:(1)
Subscription		24			25			24			23			24			25
Hardware and services		3			3			4			3			3			3
Total cost of revenue		27			28			28			26			27			28
Gross profit		73			72			72			74			73			72
Operating expense:(1)
Research and development		26			26			25			27			26			26
Sales and marketing		47			48			47			47			47			48
General and administrative		12			12			10			9			12			12
Total operating expense		85			86			82			83			85			86
Operating loss		(12	)		(14	)		(10	)		(9	)		(12	)		(14	)
Interest expense		(1	)		(2	)		(5	)		(4	)		(1	)		(2	)
Other income, net		—			—			—			—			—			—
Loss before income taxes		(13	)		(16	)		(15	)		(13	)		(13	)		(16	)
(Provision for) benefit from income taxes		(2	)		2			2			(3	)		(2	)		2
Net loss		(15	)%		(14	)%		(13	)%		(16	)%		(15	)%		(14	)%

							Year Ended December 31,
	Year Ended December 31,						2020		2019		2018
	2019		2018		2017
	(in thousands)						(in thousands)
Stock-based compensation:
Cost of subscription revenue	$	16,966	$	14,012	$	10,635	$	20,571	$	16,966	$	14,012
Cost of hardware and services revenue	$	4,001	$	2,287	$	1,893	$	5,469	$	4,001	$	2,287
Research and development	$	50,739	$	40,204	$	30,588	$	63,504	$	50,739	$	40,204
Sales and marketing	$	61,858	$	50,320	$	33,962	$	74,568	$	61,858	$	50,320
General and administrative	$	42,761	$	35,885	$	20,382	$	22,587	$	42,761	$	35,885
Amortization of intangible assets:
Cost of subscription revenue	$	30,760	$	26,971	$	14,512	$	41,277	$	30,760	$	26,971
Research and development	$	—	$	45	$	60	$	—	$	—	$	45
Sales and marketing	$	14,888	$	14,141	$	3,934	$	16,228	$	14,888	$	14,141

																				Year Ended December 31,				Change					Year Ended December 31,				Change
	Year Ended December 31,				Change					Year Ended December 31,				Change						2020		2019		$		%			2019		2018		$		%
	2019		2018		$		%			2018		2017		$			%
	(in thousands)									(in thousands)										(in thousands)									(in thousands)
Subscription	$	875,006	$	704,400	$	170,606		24	%	$	704,400	$	506,355	$	198,045			39	%	$	1,031,045	$	875,006	$	156,039		18	%	$	875,006	$	704,400	$	170,606		24	%
Hardware and services		13,184		12,594		590		5	%		12,594		13,326		(732	)		(5	)%		18,965		13,184		5,781		44	%		13,184		12,594		590		5	%
Total revenue	$	888,190	$	716,994	$	171,196		24	%	$	716,994	$	519,681	$	197,313			38	%	$	1,050,010	$	888,190	$	161,820		18	%	$	888,190	$	716,994	$	171,196		24	%

Subscription revenue increased $156.0 million and $170.6 million, or 18% and ~~$198.0 million, or~~ 24% ~~and 39%~~, respectively, for ~~2019~~2020 and ~~2018.~~2019. These increases were due to a ~~$128.6~~$114.3 million and ~~$153.1~~$128.6 million increase in revenue from the United States and a ~~$42.0~~$41.7 million and ~~$44.9~~$42.0 million increase from international customers for ~~2019~~2020 and ~~2018,~~2019, respectively.

The increases in subscription revenue for ~~2019~~2020 and ~~2018~~2019 were due to the ongoing demand for our solutions, increase in add-on activity and renewal rate being ~~higher than~~ 90%. or higher. Our enterprise customer count, which consists of customers that generate more than $10,000 in annual recurring revenue, increased from approximately ~~6,100~~7,100 at the end of ~~2018~~2019 to approximately ~~7,100,~~8,000, or ~~16%~~13%, at the end of ~~2019.~~2020. We had 6,100 enterprise customers at the end of 2018. In addition, the number of customers with three or more products increased 39% in 2020 and 38% in 2019 as compared to ~~2018. Our enterprise customer count increased from approximately 4,400 at the end of 2017 to approximately 6,100, or 39%, at the end of 2018.~~2019 and 2018, respectively. The revenue recognized from acquired deferred revenue related to the acquisitions we made was $5.5 million, $5.8 million and $20.8 million in 2020, 2019 and ~~$3.2 million in 2019,~~ 2018, ~~and 2017,~~ respectively. The change in subscription revenue due to pricing was not significant for either period.

Hardware and services revenue for 2020 increased $5.8 million, or 44%, as compared to 2019, primarily due to an increase in hardware revenue of $1.8 million and an increase in professional service revenue of $4.0 million primarily due to the timing of completion of service. Hardware and services revenue for 2019 increased $0.6 million or 5%, as compared to 2018, primarily due to higher professional service revenue. ~~The decrease in hardware and services revenue in 2018 as compared to 2017 was $0.7 million or 5%, primarily due to lower professional service revenue.~~

																			Year Ended December 31,				Change					Year Ended December 31,				Change
	Year Ended December 31,				Change					Year Ended December 31,				Change					2020		2019		$		%			2019		2018		$		%
	2019		2018		$		%			2018		2017		$		%
	(in thousands)									(in thousands)									(in thousands)									(in thousands)
Subscription	$	206,997	$	180,253	$	26,744		15	%	$	180,253	$	125,832	$	54,421		43	%	$	240,615	$	206,997	$	33,618		16	%	$	206,997	$	180,253	$	26,744		15	%
Hardware and services		29,217		21,508		7,709		36	%		21,508		17,546		3,962		23	%		34,844		29,217		5,627		19	%		29,217		21,508		7,709		36	%
Total cost of revenue	$	236,214	$	201,761	$	34,453		17	%	$	201,761	$	143,378	$	58,383		41	%	$	275,459	$	236,214	$	39,245		17	%	$	236,214	$	201,761	$	34,453		17	%

Cost of subscription revenue increased $33.6 million, or 16%, in 2020 as compared to 2019, and $26.7 million, or 15%, in 2019 as compared to ~~2018, and $54.4 million, or 43%, in 2018 as compared to 2017.~~2018. The increases were primarily due to increases in operations-related expense of ~~$13.9~~$23.9 million and ~~$35.4~~$13.9 million, respectively, due to increased headcount, network expense due to an increase in usage, depreciation expense as a result of higher capital expenditures to support our growth, and larger amortization of intangible assets expense of developed technology from recent acquisitions. Additionally, support-related expenses increased ~~$10.9~~$10.5 million and ~~$13.3~~$10.9 million, respectively, primarily due to higher headcount and consulting costs. ~~Data center costs increased $5.3 million in 2018 as compared to 2017 due to the expansion.~~

Cost of hardware and services revenue for 2020 and 2019 increased $5.6 million and ~~2018 increased~~ $7.7 million, or 19% and ~~$4.0 million, or~~ 36% ~~and 23%~~, respectively, as compared to the year before, primarily due to an increase in professional service costs of $4.5 million and $7.6 million, respectively, as our headcount increased. Additionally, the cost of hardware units sold increased $0.8 million in 2020.

																							Year Ended December 31,						Change					Year Ended December 31,						Change
	Year Ended December 31,						Change					Year Ended December 31,						Change					2020			2019			$		%			2019			2018			$		%
	2019			2018			$		%			2018			2017			$		%
	(in thousands)											(in thousands)											(in thousands)											(in thousands)
Research and development	$	230,463		$	185,391		$	45,072		24	%	$	185,391		$	129,803		$	55,588		43	%	$	283,799		$	230,463		$	53,336		23	%	$	230,463		$	185,391		$	45,072		24	%
Percent of total revenue		26	%		26	%							26	%		25	%							27	%		26	%							26	%		26	%

Research and development expenses increased $53.3 million and $45.1 million, or 23% and ~~$55.6 million, or~~ 24% ~~and 43%~~, for ~~2019~~2020 and ~~2018,~~2019, respectively. The increases were primarily due to increases in personnel-related costs of $47.6 million and $40.3 million for 2020 and ~~$46.1 million for~~ 2019, ~~and 2018,~~ respectively, from higher headcount, including those from the integration of the acquisitions in ~~2019~~2020 and ~~2018.~~2019. Additionally, corporate expense allocated to research and development increased $3.2 million and $4.7 million for 2020 and ~~$7.9 million for~~ 2019, ~~and 2018,~~ respectively, primarily due to higher costs from expanded operations, higher allocated costs from facilities, human resources and IT-related expense as we grew year-over-year. ~~Outside service expenses increased $1.0 million and travel related expenses increased $0.4 million in 2018 as compared to 2017.~~

																							Year Ended December 31,						Change					Year Ended December 31,						Change
	Year Ended December 31,						Change					Year Ended December 31,						Change					2020			2019			$		%			2019			2018			$		%
	2019			2018			$		%			2018			2017			$		%
	(in thousands)											(in thousands)											(in thousands)											(in thousands)
Sales and marketing	$	416,717		$	345,368		$	71,349		21	%	$	345,368		$	248,694		$	96,674		39	%	$	488,235		$	416,717		$	71,518		17	%	$	416,717		$	345,368		$	71,349		21	%
Percent of total revenue		47	%		48	%							48	%		47	%							47	%		47	%							47	%		48	%

Sales and marketing expenses increased $71.5 million and $71.3 million, or 17% and ~~$96.7 million, or~~ 21% ~~and 39%~~, for ~~2019~~2020 and ~~2018,~~2019, respectively. The increase in headcount on a worldwide basis and increase in revenue resulted in increased personnel-related and commissions costs of $78.1 million and $59.7 million, for 2020 and ~~$65.8 million, for~~ 2019, ~~and 2018, respectively. Travel expenses increased $4.2 million and $4.5 million in 2019 and 2018,~~ respectively. Corporate and facilities expenses allocated to sales and marketing increased $3.9 million in 2020 and $2.6 million in 2019 ~~and $6.1 million in 2018~~ due to costs related to our acquisitions and higher allocated costs as the company expanded. ~~Marketing~~Amortization expense of acquired intangible assets increased $1.3 million and $0.7 million in 2020 and 2019, respectively. These increases for 2020 were partially offset by the decreases of $11.4 million in travel expensedue to travel restrictions imposed by COVID-19. Travel expenses increased $4.2 million in 2019, while marketing expenses related to lead generation, trade shows, advertising and other initiatives increased $6.1 million in ~~2019 and $8.0 million in 2018. Amortization expense of acquired intangible assets increased $0.7 million and $10.2 million in 2019 and 2018, respectively.~~2019.

																							Year Ended December 31,						Change						Year Ended December 31,						Change
	Year Ended December 31,						Change					Year Ended December 31,						Change					2020			2019			$			%			2019			2018			$		%
	2019			2018			$		%			2018			2017			$		%
	(in thousands)											(in thousands)											(in thousands)												(in thousands)
General and administrative	$	109,727		$	86,185		$	23,542		27	%	$	86,185		$	52,735		$	33,450		63	%	$	97,713		$	109,727		$	(12,014	)		(11	)%	$	109,727		$	86,185		$	23,542		27	%
Percent of total revenue		12	%		12	%							12	%		10	%							9	%		12	%								12	%		12	%

General and administrative expenses decreased $12.0 million, or 11%, in 2020 as compared to 2019. In the three months ended June 30, 2020, management determined that the performance conditions for certain performance stock units were not probable to be achieved, as a result, due to the change in estimate and cumulative catch-up adjustment, the expense associated with those performance stock units decreased $17.9 million in 2020, as compared to 2019. Additionally, a non-recurring one-year RSU grant to the Chief Executive Officer fully vested in June 2019, and, as such the expense in 2020 were reduced $6.5 million. Remaining personnel-related costs increased $13.7 million due to an increase in headcount to support our continued growth as a public company. Outside consulting and audit costs decreased $4.5 million, and acquisition related costs decreased $2.5 million primarily due to the timing of business acquisitions made. The decreases were partially offset by a $2.9 million increase in corporate and facilities expense due to an increase in headcount. Legal expense increased $3.7 million primarily due to trade secret litigation brought by us against a third party.

General and administrative expenses increased $23.5 million, or 27%, in 2019 as compared to ~~2018, and $33.5 million, or 63%, in 2018 as compared to 2017. Personnel-related~~2018. Personnel-related costs increased $14.3 million ~~and $25.6 million for 2019 and 2018, respectively,~~ due to an increase in headcount to support our continued growth as a public company. Corporate and facilities expense increased ~~$2.2~~$1.3 million ~~and $2.1 million for 2019 and 2018, respectively,~~ primarily due to an increase in headcount. Legal expense increased $1.9 million in 2019 due to trade secret litigation brought by us against a third party. Outside consulting and audit costs increased $3.6 million ~~and $1.8 million for 2019 and 2018, respectively,~~ primarily due to ~~investments~~costs for our new accounting systems implemented in ~~business applications,~~2019, and other accounting related costs. Acquisition related costs increased $1.9 million ~~and $1.8 million~~ in 2019, ~~and 2018~~ primarily due to the timing of business acquisitions made. ~~Legal expense increased $0.9 million and $1.4 million in 2019 and 2018.~~

Interest expense ~~for~~increased $23.7 million in 2020 as compared to 2019, ~~was~~ due to the 2024 Notes issued on August 23, ~~2019 and~~2019. The increases consisted of higher accretion of ~~$11.7~~$22.2 million and higher cash interest expense of ~~$0.8~~$1.5 million.

Interest expense for 2018 consisted of the 2020 Notes accretion expense of $8.4 million, loss on conversion of the 2020 Notes of $7.2 million and cash interest expense of $1.2 million (see Note 10 “Convertible Senior Notes” to the Consolidated Financial Statements).

Interest expense decreased $11.4 million in 2018, primarily due to decreases in accretion expense and cash interest expense of $13.4 million and $3.0 million, respectively, because of conversions of the 2018 Notes in 2017 and the 2020 Notes in the third

~~quarter of 2018, offset by a $4.5 million increase in loss on conversion of the 2018 Notes and 2020 Notes (see Note 10 “Convertible Senior Notes” to the Consolidated Financial Statements).~~

Other income, net decreased $6.6 million in 2020 as compared to 2019, primarily due to a $5.4 million decrease in interest income from cash and investments due to a reduction in investments and lower interest rate, and a $1.0 million increase in foreign currency translation loss.

Other income, net increased $5.6 million in 2019 as compared to 2018 because of an increase in interest income of $6.3 million due to higher cash and investment balances, partially offset by a $0.9 million increase in foreign currency translation losses.

~~Other income, net decreased $2.3 million in 2018 as compared to 2017, primarily due to a $1.5 million increase in foreign currency translation losses and $0.4 million reduction in interest income.~~

Total provision for income taxes increased $13.0 million in 2020 as compared to 2019. The increase was primarily due to an increase of tax expense of $9.4 million related to the transfers of intellectual property between our consolidated entities, a $2.8 million increase of foreign taxes related to operations in our non-US subsidiaries and a $1.0 million increase related to uncertain tax positions.

Total provision for income taxes increased $33.1 million in 2019 as compared to 2018. The increase was primarily due to a transfer of intellectual property from Israel to the U.S., which occurred in 2019 and resulted in $17.7 million of tax expense, combined with a $14.7 million deferred tax benefit, which occurred in 2018 related to changes in the U.S. valuation allowance resulting from the Wombat business acquisition.

Total benefit from income taxes increased $3.3 million in 2018 as compared to 2017. The increase was primarily due to a $14.7 million deferred tax benefit from the Wombat business acquisition in 2018 as compared to a $12.3 million benefit from the businesses acquired in 2017 and a $1.1 million benefit for U.K. research and development credits recorded in 2018.

The following table sets forth our unaudited quarterly consolidated statements of operations data for each of the eight quarters in the period ended December 31, ~~2019.~~2020. We have prepared the quarterly data on a basis consistent with our audited annual financial statements, including, in the opinion of management, all normal recurring adjustments necessary for the fair statement of the financial information contained in these statements. The historical results are not necessarily indicative of future results and should be read in conjunction with our consolidated financial statements and the related notes included elsewhere in this Annual Report on Form 10-K.

																									Three Months Ended
	Three Months Ended																								Dec. 31, 2020			Sept. 30, 2020			June 30, 2020			Mar. 31, 2020			Dec. 31, 2019			Sept. 30, 2019			June 30, 2019			Mar. 31, 2019
	Dec. 31, 2019			Sept. 30, 2019			June 30, 2019			Mar. 31, 2019			Dec. 31, 2018			Sept. 30, 2018			June 30, 2018			Mar. 31, 2018
	(in thousands, except per share amounts)																								(in thousands, except per share amounts)
Consolidated Statements of Operations Data:
Revenue:
Subscription	$	240,367		$	224,275		$	210,780		$	199,584		$	195,089		$	181,505		$	169,019		$	158,787		$	271,412		$	260,672		$	254,892		$	244,069		$	240,367		$	224,275		$	210,780		$	199,584
Hardware and services		3,062			3,110			3,659			3,353			3,390			2,674			2,856			3,674			3,717			5,997			3,546			5,705			3,062			3,110			3,659			3,353
Total revenue		243,429			227,385			214,439			202,937			198,479			184,179			171,875			162,461			275,129			266,669			258,438			249,774			243,429			227,385			214,439			202,937
Cost of revenue:(1)
Subscription		55,789			52,308			50,648			48,252			46,758			45,679			45,618			42,198			61,430			60,144			59,193			59,848			55,789			52,308			50,648			48,252
Hardware and services		7,473			7,573			7,180			6,991			6,237			5,258			5,154			4,859			8,602			8,777			8,382			9,083			7,473			7,573			7,180			6,991
Total cost of revenue		63,262			59,881			57,828			55,243			52,995			50,937			50,772			47,057			70,032			68,921			67,575			68,931			63,262			59,881			57,828			55,243
Gross profit		180,167			167,504			156,611			147,694			145,484			133,242			121,103			115,404			205,097			197,748			190,863			180,843			180,167			167,504			156,611			147,694
Operating expense:(1)
Research and development		61,969			60,060			55,185			53,249			48,215			45,917			47,527			43,732			71,559			71,743			70,602			69,895			61,969			60,060			55,185			53,249
Sales and marketing		111,374			105,502			102,837			97,004			92,554			90,006			84,911			77,897			127,500			121,294			116,279			123,162			111,374			105,502			102,837			97,004
General and administrative		29,633			26,388			27,881			25,825			25,754			23,877			19,029			17,525			27,525			25,821			14,812			29,555			29,633			26,388			27,881			25,825
Total operating expense		202,976			191,950			185,903			176,078			166,523			159,800			151,467			139,154			226,584			218,858			201,693			222,612			202,976			191,950			185,903			176,078
Operating loss		(22,809	)		(24,446	)		(29,292	)		(28,384	)		(21,039	)		(26,558	)		(30,364	)		(23,750	)		(21,487	)		(21,110	)		(10,830	)		(41,769	)		(22,809	)		(24,446	)		(29,292	)		(28,384	)
Interest expense		(8,828	)		(3,698	)		—			—			—			(9,746	)		(3,531	)		(3,484	)		(9,202	)		(9,106	)		(9,013	)		(8,920	)		(8,828	)		(3,698	)		—			—
Other income (expense), net		3,544			2,180			659			726			550			224			(289	)		1,006
Other (expense) income, net																										(2,862	)		(119	)		(1,092	)		4,621			3,544			2,180			659			726
Loss before income taxes		(28,093	)		(25,964	)		(28,633	)		(27,658	)		(20,489	)		(36,080	)		(34,184	)		(26,228	)		(33,551	)		(30,335	)		(20,935	)		(46,068	)		(28,093	)		(25,964	)		(28,633	)		(27,658	)
(Provision for) benefit from income taxes		(641	)		(18,376	)		(280	)		(620	)		(746	)		20			(114	)		14,072
Provision for income taxes																										(1,551	)		(1,540	)		(1,660	)		(28,169	)		(641	)		(18,376	)		(280	)		(620	)
Net loss	$	(28,734	)	$	(44,340	)	$	(28,913	)	$	(28,278	)	$	(21,235	)	$	(36,060	)	$	(34,298	)	$	(12,156	)	$	(35,102	)	$	(31,875	)	$	(22,595	)	$	(74,237	)	$	(28,734	)	$	(44,340	)	$	(28,913	)	$	(28,278	)
Net loss per share, basic and diluted	$	(0.51	)	$	(0.79	)	$	(0.52	)	$	(0.51	)	$	(0.39	)	$	(0.69	)	$	(0.67	)	$	(0.24	)	$	(0.61	)	$	(0.55	)	$	(0.39	)	$	(1.30	)	$	(0.51	)	$	(0.79	)	$	(0.52	)	$	(0.51	)
Weighted average shares outstanding, basic and diluted		56,474			56,014			55,768			55,335			54,805			52,184			50,935			50,504			57,335			57,616			57,369			56,974			56,474			56,014			55,768			55,335

																	Three Months Ended
	Three Months Ended																Dec. 31, 2020		Sept. 30, 2020		June 30, 2020			Mar. 31, 2020		Dec. 31, 2019		Sept. 30, 2019		June 30, 2019		Mar. 31, 2019
	Dec. 31, 2019		Sept. 30, 2019		June 30, 2019		Mar. 31, 2019		Dec. 31, 2018		Sept. 30, 2018		June 30, 2018		Mar. 31, 2018
	(in thousands)																(in thousands)
Stock-based compensation:
Cost of subscription revenue	$	4,303	$	4,519	$	4,269	$	3,875	$	3,610	$	3,503	$	3,448	$	3,451	$	4,662	$	5,132	$	5,235		$	5,542	$	4,303	$	4,519	$	4,269	$	3,875
Cost of hardware and services revenue		998		1,043		1,054		906		651		474		571		591		1,288		1,402		1,408			1,371		998		1,043		1,054		906
Research and development		12,983		13,735		12,522		11,499		10,505		9,678		9,986		10,035		15,006		16,462		16,431			15,605		12,983		13,735		12,522		11,499
Sales and marketing		15,790		16,515		15,799		13,754		13,245		13,191		12,382		11,502		19,039		19,963		17,047			18,519		15,790		16,515		15,799		13,754
General and administrative		9,897		9,871		12,006		10,987		11,732		11,250		7,410		5,493		7,771		7,948		(3,660	)		10,528		9,897		9,871		12,006		10,987
Total stock-based compensation expenses	$	43,971	$	45,683	$	45,650	$	41,021	$	39,743	$	38,096	$	33,797	$	31,072	$	47,766	$	50,907	$	36,461		$	51,565	$	43,971	$	45,683	$	45,650	$	41,021
Amortization of intangible assets:
Cost of subscription revenue	$	8,607	$	7,886	$	7,505	$	6,762	$	6,830	$	7,121	$	7,244	$	5,776	$	10,591	$	10,756	$	9,992		$	9,938	$	8,607	$	7,886	$	7,505	$	6,762
Research and development		—		—		—		—		—		15		15		15
Sales and marketing		4,085		3,632		3,634		3,537		3,762		3,982		3,982		2,415		3,821		3,947		3,947			4,513		4,085		3,632		3,634		3,537
Total amortization of intangible assets	$	12,692	$	11,518	$	11,139	$	10,299	$	10,592	$	11,118	$	11,241	$	8,206	$	14,412	$	14,703	$	13,939		$	14,451	$	12,692	$	11,518	$	11,139	$	10,299

The following unaudited table sets forth our consolidated results of operations data as a percentage of total revenue.

	Three Months Ended																								Three Months Ended
	Dec. 31, 2019			Sept. 30, 2019			June 30, 2019			Mar. 31, 2019			Dec. 31, 2018			Sept. 30, 2018			June 30, 2018			Mar. 31, 2018			Dec. 31, 2020			Sept. 30, 2020			June 30, 2020			Mar. 31, 2020			Dec. 31, 2019			Sept. 30, 2019			June 30, 2019			Mar. 31, 2019
Consolidated Statements of Operations Data:
Revenue:
Subscription		99	%		99	%		98	%		98	%		98	%		99	%		98	%		98	%		99	%		98	%		99	%		98	%		99	%		99	%		98	%		98	%
Hardware and services		1			1			2			2			2			1			2			2			1			2			1			2			1			1			2			2
Total revenue		100			100			100			100			100			100			100			100			100			100			100			100			100			100			100			100
Cost of revenue:
Subscription		23			23			24			24			24			25			27			26			23			23			23			24			23			23			24			24
Hardware and services		3			3			3			3			3			3			3			3			3			3			3			4			3			3			3			3
Total cost of revenue		26			26			27			27			27			28			30			29			26			26			26			28			26			26			27			27
Gross profit		74			74			73			73			73			72			70			71			74			74			74			72			74			74			73			73
Operating expense:
Research and development		25			26			26			26			24			25			28			27			26			27			27			28			25			26			26			26
Sales and marketing		46		��	46			48			48			47			49			49			48			46			45			45			49			46			46			48			48
General and administrative		12			12			13			13			13			13			11			11			10			10			6			12			12			12			13			13
Total operating expense		83			84			87			87			84			87			88			86			82			82			78			89			83			84			87			87
Operating loss		(9	)		(10	)		(14	)		(14	)		(11	)		(15	)		(18	)		(15	)		(8	)		(8	)		(4	)		(17	)		(9	)		(10	)		(14	)		(14	)
Interest expense		(4	)		(2	)		—			—			—			(5	)		(2	)		(2	)		(3	)		(3	)		(4	)		(4	)		(4	)		(2	)		—			—
Other income (expense), net		1			1			1			—			—			—			—			1
Other (expense) income, net																										(1	)		—			—			2			1			1			1			—
Loss before income taxes		(12	)		(11	)		(13	)		(14	)		(11	)		(20	)		(20	)		(16	)		(12	)		(11	)		(8	)		(19	)		(12	)		(11	)		(13	)		(14	)
(Provision for) benefit from income taxes		—			(8	)		—			—			—			—			—			9
Provision for income taxes																										(1	)		(1	)		(1	)		(11	)		—			(8	)		—			—
Net loss		(12	)%		(19	)%		(13	)%		(14	)%		(11	)%		(20	)%		(20	)%		(7	)%		(13	)%		(12	)%		(9	)%		(30	)%		(12	)%		(19	)%		(13	)%		(14	)%

As of December 31, ~~2019,~~2020, we had ~~$847.6~~$910.3 million in cash and cash ~~equivalents and $43.4 million in short-term investments, for a total of $890.9 million.~~equivalents. Also refer to Note 10 “Convertible Senior Notes” to the consolidated financial statements for discussion of the 2024 Notes. The Company’s financial condition and liquidity remain strong. Net cash provided by operations was $264.5 million in 2020 compared to $242.5 million in 2019. Although there is uncertainty related to the anticipated impact of the recent COVID-19 outbreak on the Company’s future results, we believe our efficient business model leaves us positioned to manage our business through this crisis as it continues to unfold. We continue to manage all aspects of our business including, but not limited to, monitoring the financial health of our customers, suppliers and other third-party relationships, implementing gross margin enhancement strategies and developing new opportunities for growth. We have also not observed any impairments of our assets or a significant change in the fair value of assets due to the COVID-19 pandemic.

On August 27, 2020, our board of directors approved a share repurchase program under which the Company is authorized to repurchase up to $300.0 million of the Company’s common stock. Repurchases under the Repurchase Program may be made through open market purchases (including through trading plans administered under pre-determined purchasing criteria), block trades and/or privately negotiated transactions, subject to market conditions, applicable legal requirements, and other relevant factors. The timing, volume and nature of the repurchases are at the discretion of management, based on its evaluation of the capital needs of the Company, market conditions, applicable legal requirements and other factors. The Repurchase Program does not have an expiration date and may be suspended or discontinued by the Company at any time without prior notice. We plan to grow our customer base by continuing to emphasize investments in sales and marketing to add new customers, expand our customers’ use of our platform, and maintain high renewal rates. We also expect to incur additional cost of subscription revenue in accordance with the resulting growth in our customer base. We believe that the combination of our ongoing improvements in gross margins, the benefits of lower sales and marketing costs associated with our renewal activity, and the fact that our contracts are structured to bill our customers in advance should enable us to improve our cash flow from operations as we grow. Based on our current level of operations and anticipated growth, both of which are expected to be consistent with recent quarters, we believe that our existing sources of liquidity will be sufficient to fund our operations for at least the next 12 months. Our future capital requirements will depend on many factors, including our rate of revenue growth, the expansion of our sales and marketing activities, and the timing and extent of spending to support product development efforts and expansion into new territories, and the timing of introductions of new features and enhancements to our solutions. To the extent that existing cash and cash equivalents and cash from operations are insufficient to fund our future activities, we may need to raise additional funds through public or private equity or debt financing. We have invested, and plan to continue investing in acquiring complementary businesses, applications and technologies, and may continue to make such investments in the future, any of which could also require us to seek equity or debt financing. Additional funds may not be available on terms favorable to us or at all.

As of December 31, ~~2019,~~2020, the amount of cash and cash equivalents held by our foreign subsidiaries was ~~$51.3~~$66.6 million, including intercompany receivable balances. If these funds were needed for our operations in the United States, we would be required to withhold foreign taxes on the funds repatriated of approximately ~~$0.7~~$0.8 million. We have not recorded a liability for these taxes, as it is our intention that the majority of these funds are indefinitely reinvested outside the United States and our current plans do not demonstrate a need to repatriate these funds to our United States operations.

Due to negative earnings and profits in our foreign subsidiaries, we have not recorded a provisional tax liability relating to the one-time mandatory transition tax imposed by the Tax Act on our accumulated foreign earnings. As the Tax Act also eliminates U.S. taxes on foreign subsidiary distributions, future earnings in foreign jurisdictions will be available for distribution to the U.S. without incremental U.S. taxes.

The following table sets forth a summary of our consolidated cash flows for the periods indicated:

										Year Ended December 31,
	Years Ended December 31,									2020			2019			2018
	2019			2018			2017
	(in thousands)									(in thousands)
Net cash provided by operating activities	$	242,508		$	184,744		$	153,686		$	264,488		$	242,508		$	184,744
Net cash used in investing activities	$	(349,465	)	$	(250,664	)	$	(190,427	)	$	(31,769	)	$	(349,465	)	$	(250,664	)
Net cash provided by (used in) financing activities	$	778,738		$	(33,861	)	$	(23,212	)
Net cash (used in) provided by financing activities										$	(174,527	)	$	778,738		$	(33,861	)

Our net loss and cash flows from operating activities are significantly influenced by our investments in headcount and data center operations to support anticipated growth. Our cash flows are also influenced by cash payments from customers. We invoice customers for the entire contract amount at the start of the term, and as such our cash flow from operations is also affected by the length of a customer contract.

Net cash provided by operating activities was $264.5 million in 2020 as compared to $242.5 million in 2019. The increase of $22.0 million was primarily due to:

Net cash provided by operating activities was $242.5 million in 2019 as compared to $184.7 million in 2018. The increase of $57.8 million was primarily due to:

The increase was offset by a $26.5 million increase in net loss, $7.2 million decrease in loss on conversion due to the 2020 Notes converted into common shares in the third quarter of 2018 (see Note 10 “Convertible Senior Notes” to the Consolidated Financial Statements), $24.5 million decrease in operating lease liabilities change primarily due to the adoption of ASC 842 effective January 1, 2019, an increase in deferred commissions change of $14.3 million due to higher billings, and an increase in prepaid expense change of $6.0 million due to the timing of payments.

~~Net cash provided by operating activities was $184.7 million in 2018 as compared to $153.7 million in 2017. The increase of $31.0 million was primarily due to:~~

The increase was offset by a $33.9 million increase in net loss, $13.4 million decrease in amortization of debt issuance costs and accretion of debt discount due to the conversion of the convertible notes in 2017 and 2018 (see Note 10 “Convertible Senior

~~Notes” to the Consolidated Financial Statements), an increase in accounts receivable change of $50.1 million, and an increase in deferred commissions change of $20.3 million due to higher billings.~~

Our primary investing activities consisted of acquisitions of businesses, capital expenditures in support of expanding our infrastructure and workforce and the purchase and sale of short-term investments. As our business grows, we expect our capital expenditures and our investment activity to continue to increase. We may also target other companies for acquisition.

Net cash used in investing activities was $31.8 million in 2020 as compared to $349.5 million in 2019. The decrease in cash used in investing activities of $317.7 million was primarily due to a $314.4 million decrease in payments for acquired businesses, and a $71.1 million decrease in cash spent to acquire short-term investments, offset by a $30.7 million decrease in maturities of short-term investments, and a $37.2 million increase in capital expenditures primarily due to a $34.6 million increase in new corporate campus related payments.

Net cash used in investing activities was $349.5 million in 2019 as compared to $250.7 million in 2018. The increase in cash used of $98.8 million was due to an increase in cash paid for business acquisitions of $93.4 million, a decrease in proceeds from sales of short-term investments of $11.9 million, an increase in purchase of short-term investments of $12.3 million, an increase in capital expenditure of $5.7 million, and a decrease in receipts from escrow account of $3.3 million, partially offset by an increase in maturities of short-term investments of $27.8 million.

Net cash used in ~~investing~~financing activities was ~~$250.7~~$174.5 million in ~~2018~~2020 as compared to ~~$190.4~~$778.7 million provided by financing activities in ~~2017.~~ 2019. The increase in cash used in financing activities of ~~$60.3~~$953.3 million was primarily due to an$901.3 million proceeds from issuance of the 2024 Notes in 2019, net of costs; $139.4 million paid to repurchase commons stock in 2020, and a $3.4 million increase in ~~cash~~withholding taxes paid ~~for business acquisitions of $68.4 million, a $36.5 million decrease in maturities of short-term investments, and a decrease in receipts from escrow account of $2.7 million,~~related to restricted stock net share settlement, partially offset by an$84.6 million used to purchase capped calls in connection with the issuance of the 2024 Notes in 2019 and a $6.2 million increase in proceeds from ~~sales of short-term investments of $11.9 million, a decrease in purchase of short-term investments of $18.1 million, and a decrease in capital expenditures of $17.4 million.~~

~~Net Cash Flows Provided in Financing Activities~~common stock issuance related to employee stock plans.

Net cash provided inby financing activities was $778.7 million in 2019 as compared to $33.9 million used in 2018. The increase in cash provided of $812.6 million was primarily due to $901.3 million in proceeds from issuance of the 2024 Notes, net of costs, partially offset by $84.6 million used to purchase capped calls in connection with the issuance of the 2024 Notes, and a $5.3 million increase in withholding taxes paid related to restricted stock net share settlement.

Net cash used in financing activities was $33.9 million in 2018 as compared to $23.2 million in 2017. The increase in cash used of $10.7 million was primarily due to a $17.9 million increase in withholding taxes paid related to restricted stock unit net share settlement, offset by a $1.9 million increase in proceeds from common stock issuance related to employee stock plans, and $5.5 million decrease in contingent consideration payment.

The following table summarizes our contractual obligations as of December 31, ~~2019~~2020 (in thousands):

	Payment Due by Period										Payment Due by Period
	Total		Less Than 1 Year		1-3 Years		3-5 Years		More than 5 years		Total		Less Than 1 Year		1-3 Years		3-5 Years		More than 5 Years
0.25% Convertible Senior Notes due 2024	$	920,000	$	—	$	—	$	920,000	$	—	$	920,000	$	—	$	—	$	920,000	$	—
Operating lease obligations(1)		228,992		20,858		47,791		41,543		118,800		260,388		26,352		64,384		46,911		122,741
Purchase obligations(2)		100,215		42,078		58,058		79		—		57,217		40,806		16,185		226		—
Total(3)	$	1,249,207	$	62,936	$	105,849	$	961,622	$	118,800	$	1,237,605	$	67,158	$	80,569	$	967,137	$	122,741

During the periods presented, we did not have, nor do we currently have, any relationships with unconsolidated entities or financial partnerships, such as entities often referred to as structured finance or special purpose entities, which would have been established for the purpose of facilitating off-balance sheet arrangements or other contractually narrow or limited purposes. We are therefore not exposed to any financing, liquidity, market or credit risk that could arise if we had engaged in those types of relationships.

Under the indemnification provisions of our standard customer agreements, we agree to indemnify, defend and hold harmless our customers against, among other things, infringement of any patents, trademarks or copyrights under any country’s laws or the misappropriation of any trade secrets arising from the customer’s legal use of our solutions. Certain indemnification provisions potentially expose us to losses in excess of the aggregate amount paid to us by the customer under the applicable customer agreement. No material claims have been made against us pursuant to these indemnification provisions to date.

Our management’s discussion and analysis of our financial condition and results of operations are based on our consolidated financial statements, which have been prepared in accordance with GAAP. GAAP requires us to make certain estimates and judgments that can affect the reported amounts of assets and liabilities, the disclosure of contingencies, and the reported amounts of revenue and expenses. We base our estimates on historical experience and on various other assumptions that we believe to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities. If actual results or events differ materially from those contemplated by us in making these estimates, our reported financial condition and results of operations for future periods could be materially affected. See “Risk Factors” for certain matters that may affect our future financial condition or results of operations. An accounting policy is deemed to be critical if it requires an accounting estimate to be made based on assumptions about matters that are uncertain at the time the estimate is made, if different estimates reasonably could have been used, or if the changes in estimate that are reasonably likely to occur could materially impact the financial statements.

Our significant accounting policies, including those considered to be critical accounting policies, are summarized in Note 1 “The Company and Summary of Significant Accounting Policies” to the accompanying consolidated financial statements in this report. The following critical accounting policies reflect significant judgments and estimates used in the preparation of our consolidated financial statements:

The Company derives its revenue primarily from: (1) subscription service revenue; (2) subscription software revenue, and (3) hardware and services, which include professional service and training revenue provided to customers related to their use of the platform. Subscription service revenue is derived from a subscription-based enterprise licensing model with contract terms typically ranging from one to three years, and consists of (1) subscription fees from the licensing of the Company’s security-as-a-service platform and it’s various components, (2) subscription fees for software with support and related future updates where the software updates are critical to the customers’ ability to derive benefit from the software due to the fast changing nature of the technology. These function together as one performance obligation, and (3) subscription fees for the right to access the Company’s customer support services for software with significant standalone functionality and support services for hardware. Subscription software revenue is primarily derived from term-based software that is deployed on the customers’ own servers and has significant standalone functionality, is recognized upon transfer of control to the customer.

We apply significant judgment in identifying and evaluating any terms and conditions in contracts which may impact revenue recognition. Most of the Company’s contracts with customers contain multiple performance obligations. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require judgment. For these contracts, we account for individual performance obligations separately if they are distinct. The transaction price is allocated to individual performance obligation on a relative standalone selling price basis. The transaction price allocated to subscription services and subscription software that does not have significant standalone functionality is determined by considering factors such as historical pricing practices, and the selling price of hardware and professional services is estimated using a cost plus model. The selling price for support of a functional subscription software license is calculated as a percentage of functional subscription software license value which is derived by analyzing internal pricing practice, customer expectations, and industry practice.

We capitalize sales commissions and associated payroll taxes paid to internal sales personnel, and referral fees paid to independent third-parties, that are incremental to the acquisition of customer contracts. These costs are recorded as deferred commissions on the consolidated balance sheets. We determine whether costs should be deferred based on sales compensation plans, if the commissions are incremental and would not have occurred absent the customer contract. Sales commissions for renewal of a subscription contract are not considered commensurate with the commissions paid for the acquisition of the initial subscription contract given the substantive difference in commission rate between new and renewal contracts. Commissions paid upon the initial acquisition of a contract are amortized over an estimated period of benefit of five years while commissions paid related to renewal contracts are amortized over a contractual renewal period. Amortization is recognized based on the expected future revenue streams under the customer contracts. Amortization of deferred sales commissions is included in sales and marketing expense in the

accompanying consolidated statements of operations. We determine the period of benefit for commissions paid for the acquisition of the initial subscription contract by taking into consideration its initial estimated customer life and the technological life of the Company’s software and related significant features.

In each of our acquisitions, we used the purchase method of accounting which requires us to allocate the fair value of the total consideration transferred to tangible and identifiable intangible assets acquired and liabilities assumed based on their estimated fair values on the date of the acquisition, with the difference between the net assets acquired and the total consideration transferred recorded as goodwill. The fair values assigned, defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between willing market participants, are based on significant estimates and assumptions determined by

management. These estimates and assumptions are inherently uncertain and subject to refinement, as a result, during the adjustment period, which may be up to one year from the acquisition date, we may record adjustments to the assets acquired or liabilities assumed with any corresponding offset to goodwill. Upon conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded within our consolidated statements of operations.

We used either the Discounted Cash Flow Method, the Cost to Recreate Method or the Relief from Royalty Method to assign fair values to acquired identifiable intangible assets. Management applies significant judgment in estimating the fair value of these intangible assets, which involved the use of significant assumptions with respect to forecasted future revenue, forecasted operating results, cost and time to build the acquired technology, developer’s profit, rate of return, royalty rates and discount rates. These models are based on reasonable estimates and assumptions given available facts and circumstances, including industry estimates and averages, as of the acquisition dates and are consistent with the plans and estimates that we use to manage our business. If the subsequent actual results and updated projections of the underlying business activity change compared with the estimates and assumptions used to develop these values, we could experience impairment charges. In addition, we have estimated the economic lives of certain acquired assets and these lives are used to calculate depreciation and amortization expense. If our estimates of the economic lives change, depreciation or amortization expenses could be accelerated or slowed.

Accounting for business combinations requires our management to make significant estimates and assumptions, especially at the acquisition date including our estimates for intangible assets as described above, contractual obligations assumed, restructuring liabilities, pre-acquisition contingencies and contingent consideration, where applicable. Although we believe the assumptions and estimates we have made in the past have been reasonable and appropriate, they are based in part on historical experience and information obtained from the management of the acquired companies and are inherently uncertain.

Unanticipated events and circumstances may occur that may affect the accuracy or validity of such assumptions, estimates or actual results.

For a given acquisition, we may identify certain pre-acquisition contingencies as of the acquisition date and may extend our review and evaluation of these pre-acquisition contingencies throughout the measurement period in order to obtain sufficient information to assess whether we include these contingencies as a part of the fair value estimates of assets acquired and liabilities assumed and, if so, to determine their estimated amounts.

If we cannot reasonably determine the fair value of a pre-acquisition contingency (non-income tax related) by the end of the measurement period, which is generally the case given the nature of such matters, we will recognize an asset or a liability for such pre-acquisition contingency if: (i) it is probable that an asset existed or a liability had been incurred at the acquisition date and (ii) the amount of the asset or liability can be reasonably estimated. Subsequent to the measurement period, changes in our estimates of such contingencies will affect earnings and could have a material effect on our results of operations and financial position.

In addition, uncertain tax positions and tax related valuation allowances assumed in connection with a business combination are initially estimated as of the acquisition date. We reevaluate these items quarterly based upon facts and circumstances that existed as of the acquisition date with any adjustments to our preliminary estimates being recorded to goodwill if identified within the measurement period. Subsequent to the measurement period or our final determination of the tax allowance’s or contingency’s estimated value, whichever comes first, changes to these uncertain tax positions and tax related valuation allowances will affect our provision for income taxes in our consolidated statements of operations and could have a material impact on our results of operations and financial position.

Goodwill, Intangible Assets and Other Long-Lived Assets - Impairment Assessments

We review goodwill for impairment annually and whenever events or changes in circumstances indicate its carrying value may not be recoverable. For the purposes of impairment testing, we have determined that we have one reporting unit. We perform the two-step impairment test, whereby we compare the fair value of the reporting unit to its carrying value. If the fair value of the reporting unit exceeds the carrying value of the net assets assigned to that unit, goodwill is not considered impaired and we are not required to perform further testing. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of the reporting unit, then we ~~must perform~~will record an impairment charge in the ~~second step of the impairment test in order to determine the implied fair value of the~~

~~reporting unit’s goodwill. If the carrying value of~~amount by which a reporting unit’s ~~goodwill~~carrying value exceeds its ~~implied~~ fair value, ~~then we would record impairment loss equal~~not to exceed the ~~difference. No impairment has been noted to date.~~carrying amount of goodwill.

We periodically review the carrying amounts of intangible assets and other long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. We measure the recoverability of these assets by comparing the carrying amount of such assets (or asset group) to the future undiscounted cash flow we expect the assets (or asset group) to generate. If we consider any of these assets to be impaired, the impairment to be recognized equals the amount by which the carrying value of the assets exceeds its fair value. We make judgments about the recoverability of purchased intangible assets whenever events or changes in circumstances indicate that impairment may exist.

Each period we evaluate the estimated remaining useful lives of intangible assets and other long-lived assets to assess whether a revision to the remaining periods of amortization is required. Assumptions and estimates about remaining useful lives of our intangible and other long-lived assets are subjective. They can be affected by a variety of factors, including external factors such as industry and economic trends and internal factors such as changes in our business strategy. Although we believe the historical assumptions and estimates we have made are reasonable and appropriate, different assumptions and estimates could materially impact our reported financial results. We did not recognize any intangible asset impairment charges to date.

We evaluate contingent liabilities including threatened or pending litigation in accordance with the authoritative guidance on contingencies. We assess the likelihood of any adverse judgments or outcomes from potential claims or legal proceedings, as well as potential ranges of probable losses, when the outcomes of the claims or proceedings are probable and reasonably estimable. A determination of the amount of accrued liabilities required, if any, for these contingencies is made after the analysis of each separate matter. Because of uncertainties related to these matters, we base our estimates on the information available at the time of our assessment. As additional information becomes available, we reassess the potential liability related to our pending claims and litigation and may revise our estimates. Any revisions in the estimates of potential liabilities could have a material impact on our operating results and financial position.

We grant performance stock units (PSUs) to key executives. The vesting of the PSUs is subject to the executive’s continuing employment and the Company's achievement of certain performance goals. We recognize share-based compensation expense for the PSUs on a straight-line basis over the requisite service period for each separately vesting portion of the award when it is probable that the performance conditions will be achieved. At each reporting period, we estimate the probability of achieving the specified performance targets associated with each PSUs. Changes in the probability estimates associated with the PSUs are accounted for in the period of change using a cumulative catch up adjustment to apply the new probability estimate. In any period in which we determine the achievement of the performance targets is not probable, we cease recording compensation expense and all previously recognized compensation expense for the PSUs is reversed.

We determine our current and deferred tax provisions based on estimates and assumptions that could differ from the actual results reflected in our income tax returns filed during the subsequent year. We record adjustments based on filed returns when we have identified and finalized them, which is generally in the fourth ~~quarters~~quarter of the subsequent year for U.S. federal and state provisions, respectively. We have placed a full valuation allowance on all net U.S. deferred tax assets because realization of these tax benefits through future taxable income cannot be reasonably assured. We intend to maintain the valuation allowance until sufficient positive evidence exists to support the reversal of the valuation allowance. Any decision to reverse part or all of the valuation allowance would be based on our estimate of future profitability. If our estimate were to be wrong, we could be required to charge potentially significant amounts to income tax expense to establish a new valuation allowance.

Our effective tax rate includes the impact of certain undistributed foreign earnings for which we partially provided taxes because we plan to reinvest the majority of such earnings indefinitely outside the United States. We plan foreign earnings remittance amounts based on projected cash flow needs as well as the working capital and long-term investment requirements of our foreign subsidiaries and our domestic operations. Material changes in our estimates of cash, working capital and long-term investment requirements in the various jurisdictions in which we do business could impact our effective tax rate. We are subject to income taxes in the United States and certain foreign countries, and we are subject to corporate income tax audits in some of these jurisdictions. We believe that our tax return positions are fully supported, but tax authorities are likely to challenge certain positions, which may not be fully sustained. However, our income tax expense includes amounts intended to satisfy income tax assessments that result from these challenges. Determining the income tax expense for these potential assessments and recording the related assets and liabilities requires management judgments and estimates. We evaluate our uncertain tax positions in accordance with the guidance for accounting for uncertainty in income taxes. We believe that our liability for uncertain tax positions is adequate. We review our liability for uncertain tax positions quarterly, and we may adjust such liability because of proposed assessments by tax authorities, changes in facts and circumstances, issuance of new regulations or new case law, previously unavailable information obtained during the course of an examination, negotiations between tax authorities of different countries concerning our transfer prices, or the expiration of statutes of limitations.

Refer to Note 1 of the notes to our consolidated financial statements in Part II, Item 8 of this Annual Report on Form 10-K for a full description of recent accounting pronouncements.

We have operations both within the United States and internationally, and we are exposed to market risks in the ordinary course of our business. These risks primarily include interest rate, foreign exchange and inflation risks, as well as risks relating to changes in the general economic conditions in the countries where we conduct business. To reduce certain of these risks, we monitor the financial condition of our large clients and limit credit exposure by collecting in advance and setting credit limits as we deem appropriate. In addition, our investment strategy has been to invest in financial instruments that are highly liquid and readily convertible into cash. To date, we have not used derivative instruments to mitigate the impact of our market risk exposures. We have also not used, nor do we intend to use, derivatives for trading or speculative purposes.

We are exposed to market risk related to changes in interest rates. Our investments primarily consist of money market funds, corporate debt securities, commercial papers, U.S. agency and Treasury securities, and certificates of deposit. As of December 31, ~~2019,~~2020, we had cash and cash equivalents ~~and~~of $910.3 million. We didn’t have short-term investments as of ~~$890.9 million. The carrying amount of our cash equivalents and short-term investments reasonably approximates fair value, due to the short maturities of these investments.~~December 31, 2020. The primary objectives of our investment activities are the preservation of capital, the fulfillment of liquidity needs and the fiduciary control of cash and investments. We do not enter into investments for trading or speculative purposes. Our investments are exposed to market risk due to a fluctuation in interest rates, which may affect our interest income and the fair market value of our investments. Due to the short-term nature of our investment portfolio, we believe only dramatic fluctuations in interest rates would have a material effect on our investments. We do not believe that an immediate 10% increase in interest rates would have a material effect on the fair market value of our portfolio. As such we do not expect our operating results or cash flows to be materially affected by a sudden change in market interest rates.

The functional currency for our wholly owned foreign subsidiaries is the U.S. dollar. Accordingly, the subsidiaries remeasure monetary assets and liabilities at period-end exchange rates, while nonmonetary items are remeasured at historical rates. Income and expense accounts are remeasured at the average exchange rates in effect during the year. Remeasurement adjustments are recognized in the consolidated statements of operations as foreign currency transaction gains or losses in the year of occurrence. Aggregate foreign currency transaction ~~gains (losses)~~losses included in determining net loss were ~~$(1.7)~~$2.8 million, ~~$(0.9)~~$1.7 million, and ~~$0.6~~$0.9 million for 2020, 2019 ~~2018,~~ and ~~2017,~~2018, respectively. Transaction gains and losses are included in other income (expense), net.

As our international operations grow, our risks associated with fluctuation in currency rates will become greater, and we will continue to reassess our approach to managing this risk. In addition, currency fluctuations or a weakening U.S. dollar can increase the costs of our international expansion. For our operating results and cash flows, we evaluated the effects of a 10% shift in exchange rates between those currencies and the U.S. dollar. We have determined that there would not be a material effect on our results of operations from such a shift. To date, we have not entered into any foreign currency hedging contracts, since exchange rate fluctuations have not had a material impact on our operating results and cash flows. Based on our current international structure, we do not plan on engaging in hedging activities in the near future.

We do not believe that inflation has had a material effect on our business, financial condition or results of operations. Nonetheless, if our costs were to become subject to significant inflationary pressures, we may not be able to fully offset such higher costs through price increases. Our inability or failure to do so could harm our business, financial condition and results of operations.

The information in response to this item is included in our consolidated financial statements, together with the report thereon of PricewaterhouseCoopers LLP, appearing in Item 15 of this Annual Report on Form 10-K, and in Item 7 under the heading Management’s Discussion and Analysis of Financial Condition and Results of Operations.

ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE

Regulations under the Securities Exchange Act of 1934, or the Exchange Act, require public companies, including us, to maintain “disclosure controls and procedures,” which are defined in Rule 13a-15(e) and Rule 15d-15(e) to mean a company’s controls

and other procedures that are designed to ensure that information required to be disclosed in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed in our reports that we file or submit under the Exchange Act is accumulated and communicated to management, including our Chief Executive Officer and Chief Financial Officer, as appropriate to allow timely decisions regarding required disclosures. Our management, with the participation of our Chief Executive Officer and Chief Financial Officer, evaluated the effectiveness of the Company’s disclosure controls and procedures as of December 31, ~~2019.~~2020. Based on their evaluation, as of December 31, ~~2019,~~2020, our Chief Executive Officer and Chief Financial Officer have concluded that the Company’s disclosure controls and procedures were effective.

Our management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Exchange Act Rule 13a-15(f) and Rule 15d-15(f). Our management, including our Chief Executive Officer and Chief Financial Officer, conducted an evaluation of the effectiveness of our internal control over financial reporting based on the framework in I~~nternal~~Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on its evaluation under the framework in Internal Control - Integrated Framework (2013), our management concluded that our internal control over financial reporting was effective as of December 31, ~~2019.~~2020.

The effectiveness of our internal control over financial reporting as of December 31, ~~2019,~~2020, has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in their report which appears in Item 15(a) of this Annual Report on Form 10-K.

There have been no changes in our internal control over financial reporting during the quarter ended December 31, ~~2019~~2020 that materially affected, or are reasonably likely to materially affect, our internal control over financial reporting. We have not experienced any material impact to our internal control over financial reporting despite the fact that most of our employees are working remotely due to the COVID-19 pandemic. We are continually monitoring and assessing the COVID-19 situation on our internal controls to minimize the impact on their design and operating effectiveness.

Management does not expect that our disclosure controls and procedures or our internal control over financial reporting will prevent or detect all error and fraud. Any control system, no matter how well designed and operated, is based upon certain assumptions and can provide only reasonable, not absolute, assurance that its objectives will be met. Further, no evaluation of controls can provide absolute assurance that misstatements due to error or fraud will not occur or that all control issues and instances of fraud, if any, within the Company have been detected.

The information required by this item will be set forth in the definitive Proxy Statement for our ~~2020~~2021 Annual Meeting of Stockholders (the “Proxy Statement”) and is incorporated into this report by reference.

The information required by this item will be set forth in the Proxy Statement and is incorporated into this report by reference.

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS

The information required by this item will be set forth in the Proxy Statement and is incorporated into this report by reference.

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE

The information required by this item will be set forth in the Proxy Statement and is incorporated into this report by reference.

Financial statement schedules have been omitted because they are not required, not applicable, not present in amounts sufficient to require submission of the schedule, or the required information is shown in the Consolidated Financial Statements or Notes thereto.

The information required by this Item is set forth in the Exhibits Index that precedes the signature page of this Annual Report on Form 10-K.

Opinions on the Financial Statements and Internal Control over Financial Reporting

We have audited the accompanying consolidated balance sheets of Proofpoint, Inc. and its subsidiaries (the “Company”) as of December 31, ~~2019~~2020 and ~~2018,~~2019, and the related consolidated statements of operations, of comprehensive loss, of stockholders' equity and of cash flows for each of the three years in the period ended December 31, ~~2019,~~2020, including the related notes (collectively referred to as the “consolidated financial statements”). We also have audited the Company's internal control over financial reporting as of December 31, ~~2019,~~2020, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, ~~2019~~2020 and ~~2018,~~2019, and the results of its operations and its cash flows for each of the three years in the period ended December 31, ~~2019~~2020 in conformity with accounting principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, ~~2019,~~2020, based on criteria established in Internal Control - Integrated Framework (2013) issued by the COSO.

As discussed in Note 1 to the consolidated financial statements, the Company changed the manner in which it accounts for leases in ~~2019.~~2019 and the manner in which it accounts for revenue from contracts with customers in 2018.

The Company's management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in Management’s Annual Report on Internal Control over Financial Reporting appearing under Item 9A. Our responsibility is to express opinions on the Company’s consolidated financial statements and on the Company's internal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects.

Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

The critical audit ~~matters~~matter communicated below ~~are matters~~is a matter arising from the current period audit of the consolidated financial statements that ~~were~~was communicated or required to be communicated to the audit committee and that (i) ~~relate~~relates to accounts or disclosures that are material to the consolidated financial statements and (ii) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit ~~matters~~matter below, providing a separate ~~opinions~~opinion on the critical audit ~~matters~~matter or on the accounts or disclosures to which ~~they relate.~~it relates.

Revenue – Identifying and evaluating terms and conditions in contracts that impact revenue recognition

As described in Note 2 to the consolidated financial statements, revenue recognition is determined by management through the following steps: 1) identification of the contract, or contracts, with a customer; 2) identification of the performance obligations in the contract; 3) determination of the transaction price; 4) allocation of the transaction price to the performance obligations in the contract; and 5) recognition of revenue when, or as, the Company satisfies a performance obligation. Management applies significant judgment in identifying and evaluating any terms and conditions in contracts which may impact revenue recognition. For the year ended December 31, ~~2019,~~2020, the Company’s revenue was ~~$888~~ $1,050million.

The principal considerations for our determination that performing procedures relating to revenue, specifically identifying and evaluating terms and conditions in contracts that impact revenue recognition, is a critical audit matter are ~~that there was~~the significant judgment by management in identifying and evaluating terms and conditions in contracts that impact revenue ~~recognition. This~~recognition; this in turn led to significant auditor judgment and effort in performing procedures to evaluate whether terms and conditions were appropriately identified and evaluated by management.

~~Acquisition of ObserveIT, Ltd. – Valuation of Developed Technology and In-process Research and Development Intangible Assets~~

As described in Note 3 to the consolidated financial statements, the Company acquired ObserveIT, Ltd. on November 25, 2019 for net consideration of $214 million, which resulted in $35 million of developed technology and $21 million of in-process research and development intangible assets being recorded. A discounted cash flow method was used to value the developed technology and in-process research and development intangible assets. Management applied significant judgement in estimating the fair value of these intangible assets, which involved the use of significant assumptions with respect to forecasted revenue, forecasted operating results and discount rates.

The principal considerations for our determination that performing procedures relating to the valuation of developed technology and in-process research and development intangible assets in the acquisition of ObserveIT, Ltd. is a critical audit matter are that there was a high degree of auditor judgment and subjectivity in applying procedures relating to the fair value measurement of the developed technology and in-process research and development intangible assets due to the significant judgment by management when developing the estimates. Significant audit effort was required in performing procedures and evaluating the significant assumptions relating to the estimates, including forecasted revenue, forecasted operating results and discount rates. The audit effort also involved the use of professionals with specialized skill and knowledge to assist in evaluating the audit evidence obtained from these procedures.

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included testing the effectiveness of controls relating to the acquisition accounting, including controls over management’s valuation of the developed technology and in-process research and development intangible assets and controls over the development of the assumptions related to the valuation, including forecasted revenue, forecasted operating results and discount rates. These procedures also included, among others, reading the purchase agreement and testing management’s process for estimating the fair value of the developed technology and in-process research and development intangible assets. Testing management’s process included (i) evaluating the appropriateness of the discounted cash flow method, (ii) testing the completeness, accuracy and relevance of underlying data used in the discounted cash flow method (ii) and evaluating the reasonableness of the significant assumptions, which involved considering the past performance of the acquired business and industry data. Professionals with specialized skill and knowledge were used to assist in the evaluation of the discounted cash flow method used by management and the reasonableness of the discount rates.

We have served as the Company’s auditor since 2008, which includes periods before the Company became subject to SEC reporting requirements.

	At December 31,						At December 31,
	2019			2018			2020			2019
Assets
Current assets:
Cash and cash equivalents	$	847,555		$	185,392		$	910,279		$	847,555
Short-term investments		43,385			46,307			0			43,385
Accounts receivable, net		265,741			199,194			255,390			265,741
Inventory		1,249			481			317			1,249
Deferred product costs		2,723			1,800			3,480			2,723
Deferred commissions		47,250			37,391			57,779			47,250
Prepaid expenses and other current assets		22,081			16,872			32,493			22,081
Total current assets		1,229,984			487,437			1,259,738			1,229,984
Property and equipment, net		73,512			70,627			111,030			73,512
Operating lease right-of-use asset		51,852			—
Operating lease right-of-use assets								182,228			51,852
Long-term deferred product costs		581			303			420			581
Goodwill		687,517			460,425			688,454			687,517
Intangible assets, net		186,023			136,645			130,392			186,023
Long-term deferred commissions		90,305			69,989			108,762			90,305
Other assets		17,737			7,592			17,686			17,737
Total assets	$	2,337,511		$	1,233,018		$	2,498,710		$	2,337,511
Liabilities and Stockholders’ Equity
Current liabilities:
Accounts payable	$	16,311		$	20,237		$	2,233		$	16,311
Accrued liabilities		119,423			90,719			132,187			119,423
Deferred rent		—			829
Operating lease liabilities		20,202			—			28,560			20,202
Deferred revenue		615,874			490,296			702,248			615,874
Total current liabilities		771,810			602,081			865,228			771,810
Convertible senior notes		749,620			—			783,561			749,620
Long-term deferred rent		—			3,757
Long-term operating lease liabilities		36,223			—			178,506			36,223
Other long-term liabilities		19,172			6,812			39,639			19,172
Long-term deferred revenue		168,189			107,834			190,032			168,189
Total liabilities		1,745,014			720,484			2,056,966			1,745,014
Commitments and contingencies (Note 9)
Stockholders’ equity:
Convertible preferred stock, $0.0001 par value; 5,000 shares authorized; 0 shares issued and outstanding as of December 31, 2019 and 2018		—			—
Common stock, $0.0001 par value; 200,000 shares authorized; 56,784 and 55,149 shares issued and outstanding at December 31, 2019 and December 31, 2018, respectively		6			6
Convertible preferred stock, $0.0001 par value; 5,000 shares authorized; 0 shares issued and outstanding as of December 31, 2020 and 2019								0			0
Common stock, $0.0001 par value; 200,000 shares authorized; 58,513 shares issued and 57,178 shares outstanding at December 31, 2020; 56,784 shares issued and outstanding at December 31, 2019								6			6
Additional paid-in capital		1,318,084			1,107,953			1,470,497			1,318,084
Accumulated other comprehensive income (loss)		1			(7	)
Treasury stock, at cost; 1,335 shares at December 31, 2020								(139,356	)		0
Accumulated other comprehensive income								0			1
Accumulated deficit		(725,594	)		(595,418	)		(889,403	)		(725,594	)
Total stockholders’ equity		592,497			512,534			441,744			592,497
Total liabilities and stockholders’ equity	$	2,337,511		$	1,233,018		$	2,498,710		$	2,337,511

The accompanying notes are an integral part of these consolidated financial statements.

	Year Ended December 31,									Year Ended December 31,
	2019			2018			2017			2020			2019			2018
Revenue:
Subscription	$	875,006		$	704,400		$	506,355		$	1,031,045		$	875,006		$	704,400
Hardware and services		13,184			12,594			13,326			18,965			13,184			12,594
Total revenue		888,190			716,994			519,681			1,050,010			888,190			716,994
Cost of revenue:(1)(2)
Subscription		206,997			180,253			125,832			240,615			206,997			180,253
Hardware and services		29,217			21,508			17,546			34,844			29,217			21,508
Total cost of revenue		236,214			201,761			143,378			275,459			236,214			201,761
Gross profit		651,976			515,233			376,303			774,551			651,976			515,233
Operating expense:(1)(2)
Research and development		230,463			185,391			129,803			283,799			230,463			185,391
Sales and marketing		416,717			345,368			248,694			488,235			416,717			345,368
General and administrative		109,727			86,185			52,735			97,713			109,727			86,185
Total operating expense		756,907			616,944			431,232			869,747			756,907			616,944
Operating loss		(104,931	)		(101,711	)		(54,929	)		(95,196	)		(104,931	)		(101,711	)
Interest expense		(12,526	)		(16,761	)		(28,608	)		(36,241	)		(12,526	)		(16,761	)
Other income, net		7,109			1,491			3,785			548			7,109			1,491
Loss before income taxes		(110,348	)		(116,981	)		(79,752	)		(130,889	)		(110,348	)		(116,981	)
(Provision for) benefit from income taxes		(19,917	)		13,232			9,950			(32,920	)		(19,917	)		13,232
Net loss	$	(130,265	)	$	(103,749	)	$	(69,802	)	$	(163,809	)	$	(130,265	)	$	(103,749	)
Net loss per share, basic and diluted	$	(2.33	)	$	(1.99	)	$	(1.58	)	$	(2.86	)	$	(2.33	)	$	(1.99	)
Weighted average shares outstanding, basic and diluted		55,902			52,111			44,258			57,324			55,902			52,111

(1) Includes stock-based compensation expense as follows:
Cost of subscription revenue	$	16,966	$	14,012	$	10,635	$	20,571	$	16,966	$	14,012
Cost of hardware and services revenue	$	4,001	$	2,287	$	1,893	$	5,469	$	4,001	$	2,287
Research and development	$	50,739	$	40,204	$	30,588	$	63,504	$	50,739	$	40,204
Sales and marketing	$	61,858	$	50,320	$	33,962	$	74,568	$	61,858	$	50,320
General and administrative	$	42,761	$	35,885	$	20,382	$	22,587	$	42,761	$	35,885

(2) Includes intangible amortization expense as follows:
Cost of subscription revenue	$	30,760	$	26,971	$	14,512	$	41,277	$	30,760	$	26,971
Research and development	$	—	$	45	$	60	$	—	$	—	$	45
Sales and marketing	$	14,888	$	14,141	$	3,934	$	16,228	$	14,888	$	14,141

The accompanying notes are an integral part of these consolidated financial statements.

	Year Ended December 31,									Year Ended December 31,
	2019			2018			2017			2020			2019			2018
Net loss	$	(130,265	)	$	(103,749	)	$	(69,802	)	$	(163,809	)	$	(130,265	)	$	(103,749	)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on investments, net		8			2			(2	)
Unrealized (loss) gain on investments, net											(1	)		8			2
Comprehensive loss	$	(130,257	)	$	(103,747	)	$	(69,804	)	$	(163,810	)	$	(130,257	)	$	(103,747	)

The accompanying notes are an integral part of these consolidated financial statements.

	Common Stock					Additional Paid-In			Accumulated Other Comprehensive			Accumulated			Total Stockholders’			Common Stock					Additional Paid-In			Treasury Stock						Accumulated Other Comprehensive			Accumulated			Total Stockholders’
	Shares			Amount		Capital			Income (Loss)			Deficit			Equity			Shares			Amount		Capital			Shares			Amount			Income (Loss)			Deficit			Equity
Balances at December 31, 2016		43,015		$	4	$	514,034		$	(7	)	$	(417,652	)	$	96,379
Cumulative effect adjustment from adoption of new accounting pronouncement		—			—		999			—			(999	)		—
Net loss		—			—		—			—			(69,802	)		(69,802	)
Unrealized loss on short-term investments		—			—		—			(2	)		—			(2	)
Conversion of convertible senior notes to common stock (Note 10)		5,159			1		193,153			—			—			193,154
Stock-based compensation expense		—			—		88,449			—			—			88,449
Acquisition of businesses (Note 3)		—			—		424			—			—			424
Common stock issued		2,672			—		34,024			—			—			34,024
Tax withholding upon vesting of restricted stock awards		(521	)		—		(43,511	)		—			—			(43,511	)
Balances at December 31, 2017		50,325			5		787,572			(9	)		(488,453	)		299,115			50,325		$	5	$	787,572			—		$	—		$	(9	)	$	(488,453	)	$	299,115
Cumulative effect adjustment from adoption of new accounting pronouncement		—			—		—			—			(3,216	)		(3,216	)		—			—		—			—			—			—			(3,216	)		(3,216	)
Net loss		—			—		—			—			(103,749	)		(103,749	)		—			—		—			—			—			—			(103,749	)		(103,749	)
Unrealized gain on short-term investments		—			—		—			2			—			2			—			—		—			—			—			2			—			2
Conversion of convertible senior notes to common stock (Note 10)		2,928			1		213,305			—			—			213,306			2,928			1		213,305			—			—			—			—			213,306
Stock-based compensation expense		—			—		131,178			—			—			131,178			—			—		131,178			—			—			—			—			131,178
Common stock issued		2,463			—		36,449			—			—			36,449			2,463			—		36,449			—			—			—			—			36,449
Tax withholding upon vesting of restricted stock awards		(567	)		—		(60,551	)		—			—			(60,551	)		(567	)		—		(60,551	)		—			—			—			—			(60,551	)
Balances at December 31, 2018		55,149			6		1,107,953			(7	)		(595,418	)		512,534			55,149			6		1,107,953			—			—			(7	)		(595,418	)		512,534
Cumulative effect adjustment from adoption of new accounting pronouncement (Note 8)		—			—		—			—			89			89
Cumulative effect adjustment from adoption of new accounting pronouncement																			—			—		—			—			—			—			89			89
Net loss		—			—		—			—			(130,265	)		(130,265	)		—			—		—			—			—			—			(130,265	)		(130,265	)
Unrealized gain on short-term investments		—			—		—			8			—			8			—			—		—			—			—			8			—			8
Stock-based compensation expense		—			—		159,694			—			—			159,694			—			—		159,694			—			—			—			—			159,694
Acquisition of businesses (Note 3)		72			—		892			—			—			892			72			—		892			—			—			—			—			892
Common stock issued		2,148			—		40,744			—			—			40,744			2,148			—		40,744			—			—			—			—			40,744
Tax withholding upon vesting of restricted stock awards		(585	)		—		(69,351	)		—			—			(69,351	)		(585	)		—		(69,351	)		—			—			—			—			(69,351	)
Embedded conversion feature on convertible senior notes (Note 10)		—			—		163,023			—			—			163,023			—			—		163,023			—			—			—			—			163,023
Purchase of capped calls (Note 10)		—			—		(84,871	)		—			—			(84,871	)		—			—		(84,871	)		—			—			—			—			(84,871	)
Balances at December 31, 2019		56,784		$	6	$	1,318,084		$	1		$	(725,594	)	$	592,497			56,784			6		1,318,084			—			—			1			(725,594	)		592,497
Net loss																			—			—		—			—			—			—			(163,809	)		(163,809	)
Unrealized gain on short-term investments																			—			—		—			—			—			(1	)		—			(1	)
Stock-based compensation expense																			—			—		174,868			—			—			—			—			174,868
Issuance of restricted shares																			11			—		—			—			—			—			—			—
Common stock issued																			2,337			—		47,563			—			—			—			—			47,563
Tax withholding upon vesting of restricted stock awards																			(619	)		—		(70,018	)		—			—			—			—			(70,018	)
Repurchase of common stock (Note 11)																			—			—		—			(1,335	)		(139,356	)		—			—			(139,356	)
Balances at December 31, 2020																			58,513		$	6	$	1,470,497			(1,335	)	$	(139,356	)	$	—		$	(889,403	)	$	441,744

The accompanying notes are an integral part of these consolidated financial statements.

	Year Ended December 31,									Year Ended December 31,
	2019			2018			2017			2020			2019			2018
Cash flows from operating activities
Net loss	$	(130,265	)	$	(103,749	)	$	(69,802	)	$	(163,809	)	$	(130,265	)	$	(103,749	)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization		80,332			73,553			42,098			95,965			80,332			73,553
Stock-based compensation		176,325			142,708			97,460			186,699			176,325			142,708
Change in fair value of contingent consideration		—			(79	)		(1,533	)		0			0			(79	)
Amortization of debt issuance costs and accretion of debt discount		11,708			8,383			21,789			33,941			11,708			8,383
Amortization of deferred commissions		50,415			37,076			28,476			62,776			50,415			37,076
Noncash lease costs		23,339			—			—			27,229			23,339			0
Loss on conversion of convertible notes		—			7,207			2,696			0			0			7,207
Deferred income taxes		(2,371	)		(15,258	)		(15,953	)		(1,982	)		(2,371	)		(15,258	)
Other		1,855			1,469			(348	)		3,239			1,855			1,469
Changes in assets and liabilities, net of effect of acquisitions:
Accounts receivable		(62,239	)		(81,890	)		(31,744	)		9,264			(62,239	)		(81,890	)
Inventory		(768	)		249			(132	)		931			(768	)		249
Deferred product costs		(1,203	)		(302	)		338			(595	)		(1,203	)		(302	)
Deferred commissions		(80,590	)		(66,254	)		(45,910	)		(91,763	)		(80,590	)		(66,254	)
Prepaid expenses		(7,915	)		(1,905	)		(1,663	)		(11,217	)		(7,915	)		(1,905	)
Other current assets		57			2,155			(139	)		(228	)		57			2,155
Long-term assets		(499	)		311			(3,429	)		171			(499	)		311
Accounts payable		(3,569	)		8,396			(1,648	)		(13,321	)		(3,569	)		8,396
Accrued liabilities		33,191			17,184			14,539			43,844			33,191			17,184
Deferred rent		—			(101	)		1,867			0			0			(101	)
Operating lease liabilities		(24,529	)		—			—			(24,874	)		(24,529	)		0
Deferred revenue		179,234			155,591			116,724			108,218			179,234			155,591
Net cash provided by operating activities		242,508			184,744			153,686			264,488			242,508			184,744
Cash flows from investing activities
Proceeds from maturities of short-term investments		93,838			66,080			102,556			63,093			93,838			66,080
Proceeds from sales of short-term investments		—			11,931			—			0			0			11,931
Purchase of short-term investments		(90,955	)		(78,688	)		(96,741	)		(19,876	)		(90,955	)		(78,688	)
Purchase of property and equipment		(35,193	)		(29,522	)		(46,958	)		(72,420	)		(35,193	)		(29,522	)
Receipts from escrow account		—			3,321			6,066			154			0			3,321
Acquisitions of business, net of cash and restricted cash acquired		(317,155	)		(223,786	)		(155,350	)		(2,720	)		(317,155	)		(223,786	)
Net cash used in investing activities		(349,465	)		(250,664	)		(190,427	)		(31,769	)		(349,465	)		(250,664	)
Cash flows from financing activities
Proceeds from issuance of common stock		28,091			27,579			25,725			34,250			28,091			27,579
Withholding taxes related to restricted stock net share settlement		(66,006	)		(60,706	)		(42,823	)		(69,421	)		(66,006	)		(60,706	)
Proceeds from issuance of convertible senior notes, net of costs		901,293			—			—			0			901,293			0
Purchase of capped calls		(84,640	)		—			—			0			(84,640	)		0
Repurchases of common stock											(139,356	)		0			0
Repayments of equipment loans and capital lease obligations		—			(37	)		(34	)		0			0			(37	)
Repayment of convertible notes		—			(142	)		(14	)		0			0			(142	)
Contingent consideration payments		—			(555	)		(6,066	)		0			0			(555	)
Net cash provided by (used in) financing activities		778,738			(33,861	)		(23,212	)
Net cash (used in) provided by financing activities											(174,527	)		778,738			(33,861	)
Effect of exchange rate changes on cash, cash equivalents and restricted cash		(26	)		(727	)		1,076			2,852			(26	)		(727	)
Net increase (decrease) in cash, cash equivalents and restricted cash		671,755			(100,508	)		(58,877	)		61,044			671,755			(100,508	)
Cash, cash equivalents, and restricted cash
Beginning of period		186,152			286,660			345,537			857,907			186,152			286,660
End of period	$	857,907		$	186,152		$	286,660		$	918,951		$	857,907		$	186,152
Supplemental disclosures of cash flow information
Cash paid for interest	$	—		$	1,249		$	4,236
Cash paid for taxes	$	10,770		$	120		$	5,311
Supplemental disclosure of noncash investing and financing activities
Unpaid purchases of property and equipment and asset retirement obligations	$	3,483		$	2,706		$	3,349
Operating lease right-of-use assets exchanged for lease obligations	$	15,668		$	—		$	—
Liability awards converted to equity	$	12,651		$	8,870		$	8,307
Convertible senior notes converted to equity	$	—		$	213,306		$	193,153

The accompanying notes are an integral part of these consolidated financial statements.

Proofpoint, Inc. (the “Company”) was incorporated in Delaware in June 2002 and is headquartered in California.

Proofpoint, Inc. is a leading security-as-a-service provider that enables large and mid-sized organizations worldwide to defend, protect, archive and govern their most sensitive data. The Company’s security-and compliance platform is comprised of an integrated suite of threat protection, information protection, and brand protection solutions, including email protection, advanced threat protection, email authentication, data loss prevention, SaaS application protection, response orchestration and automation, digital risk, web browser isolation, email encryption, archiving, eDiscovery, supervision, secure communication, phishing simulation and security awareness computer-based training.

Management has determined that in the Company’s consolidated financial statements for the year ended December 31, 2018, short-term deferred revenue was overstated by $2,446, or 0.5%, in its consolidated balance sheet as of December 31, 2018. The Company has revised the December 31, 2018 consolidated balance sheet to correct the classification from short-term deferred revenue to long-term deferred revenue. The correction had no impact on the results of operations or cash flows of the Company.

The accompanying consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”). The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

During the reporting periods, the Company completed a number of acquisitions which are more fully described in Note 3 “Acquisitions”. The consolidated financial statements include the results of operations from these business combinations from their date of acquisition.

Certain reclassifications have been made to prior year balances in order to conform to the current period presentation. “Interest income” has been reclassified from “Interest expense” to “Other income, net” in the consolidated statements of operations. The reclassifications had no impact on previously reported net loss or accumulated deficit.

The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates. Significant items subject to such estimates and assumptions include those related to revenue recognition, deferred commissions, fair value of assets acquired and liabilities assumed in business combinations, impairment assessments of goodwill, intangible assets and other long-lived assets, loss contingencies, stock-based compensation, and income taxes.

Due to the Coronavirus (“COVID-19”) pandemic, there has been uncertainty and disruption in the global economy and financial markets. The Company is not aware of any specific event or circumstance that would require an update to its estimates or judgments or a revision of the carrying value of its assets or liabilities as of December 31, 2020. These estimates may change, as new events occur and additional information is obtained, as well as other factors related to COVID-19 that could result in material impacts to our consolidated financial statements in future reporting periods.

The functional currency of the Company’s wholly-owned foreign subsidiaries is the U.S. dollar. Accordingly, the subsidiaries remeasure monetary assets and liabilities at period-end exchange rates, while

nonmonetary items are remeasured at historical rates. Income and expense accounts are remeasured at the average exchange rates in effect during the year. Remeasurement adjustments are recognized in the consolidated statements of operations as transaction gains or losses within other income, ~~(expense),~~ net, in the period of occurrence. Aggregate transaction ~~gains (losses)~~losses included in determining net loss were ~~$(1,655), $(943)~~$2,847, $1,655 and ~~$574~~$943 for the years ended December 31, 2020, 2019 and 2018, respectively.

(dollars and ~~2017, respectively.~~share amounts in thousands, except per share amounts)

The Company considers currency on hand, demand deposits, time deposits, money market funds and all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash and cash equivalents. Cash and cash equivalents are held in various financial institutions in the United States and internationally.

The Company classifies all its investments as available-for-sale at the time of purchase since it is management’s intent that these investments be available for current operations, and as such, includes these investments as short-term investments on its balance sheets. These investments consist of money market funds, corporate debt securities, commercial papers, U.S. agency and Treasury securities, and certificates of deposit with original maturities longer than three months. Short-term investments classified as available-for-sale are recorded at fair value with the related unrealized gains and losses included in accumulated other comprehensive income (loss), a component of stockholders’ equity. Realized gains and losses are recorded in the consolidated statements of operations and comprehensive loss based on specific identification.

Inventories are stated at lower of cost or net realizable value, with costs computed on a first-in, first-out basis. The Company periodically reviews its inventories for excess and obsolete items and adjusts carrying costs to estimated net realizable values when they are determined to be less than cost. Inventories held at December 31, ~~2019~~2020 and December 31, ~~2018~~2019 consist primarily of finished goods.

Effective January 1, 2018, the Company adopted ASC 606 using the full retrospective method. Refer to Note 2 for a detailed discussion of accounting policies related to revenue recognition, including deferred revenue, deferred commissions and deferred product costs.

Property and equipment are stated at cost. Depreciation is computed using the straight-line method over the estimated useful life of the related asset. Amortization of leasehold improvements is computed using the straight-line method over the shorter of the lease term or the estimated useful life of the asset or improvement. Cost of maintenance and repairs that do not improve or extend the lives of the respective assets are expensed as incurred.

The Company evaluates long-lived assets, including property, equipment and definitive-lived intangible assets, for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. Recoverability of these assets is measured by comparison of the carrying amount of such assets (or asset group) to the future undiscounted cash flows the assets (or asset group) is expected to generate. If the assets are considered to be impaired, the amount of any impairment is measured as the difference between the carrying value and the fair value of the impaired assets. The Company also evaluates the estimated remaining useful lives of intangible assets and other long-lived assets to assess whether a revision to the remaining periods of amortization is required. NaN assets were determined to be impaired as of December 31, ~~2019.~~

Internally developed software includes security software developed to meet the Company’s internal needs to provide cloud-based subscription services to its end-customers and business software that the Company customizes to meet its operating needs. These capitalized costs consist of internal compensation related costs and external direct costs incurred during the application development stage. The costs capitalized were not material in the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017.~~2018.

The costs to develop software that is marketed externally have not been capitalized as the current software development process is essentially completed concurrently with the establishment of technological feasibility. As such, all related software development costs are expensed as incurred and included in research and development expense in the consolidated statements of operations.

Internally and externally developed software is amortized over the software’s estimated useful life of three to ~~five~~six years.

Expenses related to advertising and promotion of solutions is charged to sales and marketing expense as incurred. The Company did not incur any material advertising and promotion expenses during the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017.~~2018.

Goodwill represents the excess of the purchase price of the acquired enterprise over the fair value of identifiable assets acquired and liabilities assumed. The Company performs an annual goodwill impairment test during the fourth quarter of a calendar year and more frequently if an event or circumstances indicates that impairment may have occurred. For the purposes of impairment testing, the Company has determined that it has 1 operating segment and 1 reporting unit. ~~The~~To test goodwill for impairment, the Company ~~performs a two-step impairment test of goodwill whereby the fair value of~~compares the reporting ~~unit is compared to~~unit’s carrying value with its ~~carrying~~fair value. If the ~~fair~~carrying value of the reporting unit exceeds the carrying value of the net assets assigned to that unit, goodwill is not considered impaired and further testing is not required. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of the reporting unit, then the Company must perform the second step of the impairment test in order to determine the implied fair value of the reporting unit’s ~~goodwill. If the carrying value of a reporting unit’s goodwill exceeds its implied~~ fair value, then the impairment ~~loss~~charge equal to the difference is ~~recorded.~~recorded; however, the loss recognized would not exceed the total amount of goodwill allocated to the reporting unit. The identification and measurement of goodwill impairment involves the estimation of the fair value of the Company. NaN impairment indicators were identified by the Company as of December 31, ~~2019.~~2020.

Intangible assets consist of developed technology, customer relationships, ~~non-compete arrangements,~~ trademarks and patents, order backlog, and in-process research and development asset. The values assigned to intangibles are based on estimates and judgments regarding expectations for success and life cycle of solutions and technologies acquired.

Intangible assets are amortized on a straight-line basis over their estimated lives, which approximate the pattern in which the economic benefits of the intangible assets are consumed, as follows (in years):

The in-process research and development asset is not amortized until the associated project is completed.

The Company provides limited warranties on all sales and provides for the estimated cost of the warranties at the date of sale, to the extent not already provided by its own vendors. Warranty costs and the accrued warranty liabilities were not material for all periods presented.

Effective January 1, 2019, the Company adopted ASC 842 using the modified retrospective method. Refer to Note 8 for a detailed discussion of accounting policies related to leases.

The Company accounts for income taxes in accordance with authoritative guidance, which requires use of the asset and liability method. Under this method, deferred income tax assets and liabilities are determined based on the difference between the consolidated financial statements carrying amounts and the tax basis of assets and liabilities and are measured using the enacted tax rates expected to apply to taxable income in the years in which the differences are expected to be reversed.

The Company records net deferred tax assets to the extent the Company believes these assets will more likely than not be realized. In making such determination, the Company considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax planning strategies and recent financial operations.

Research and development expense consists primarily of personnel costs, consulting services, allocated facilities costs and depreciation. Research and development costs are expensed as incurred.

The Company’s tax-deferred savings plan is qualified under Section 401(k) of the United States Internal Revenue Code. Employees may make voluntary, tax-deferred contributions to the 401(k) Plan up to the statutorily prescribed annual limit. The Company makes discretionary matching contributions to the 401(k) Plan on behalf of employees up to the limit determined by the Board of Directors. The Company contributed $2,802, $2,816 and $1,563 to the 401(k) Plan in 2020, 2019 and ~~2018. There were 0 contributions made by the Company in 2017.~~2018, respectively.

The Company issues stock-based compensation awards to employees and directors in the form of stock options, restricted stock units (“RSUs”), performance stock units (“PSUs”), employee stock purchase plan (“ESPP”) and stock bonus and other liability awards (collectively, “awards”).

The Company measures and recognizes compensation expense for all stock-based awards based on the awards’ fair value. Stock-based compensation for RSUs is measured based on the value of the Company’s common stock on the grant date. The Company accounts for forfeitures as they occur.

The actual number of PSUs earned and eligible to vest are determined based on the Company’s achievement of the financial and operational performance conditions pre-defined when the awards are granted. The Company recognizes share-based compensation expense for the PSUs on a straight-line basis over the requisite service period for each separately vesting portion of the award when it is probable that the performance conditions will be achieved. The Company reassesses the probability of vesting at each reporting period for awards with performance conditions and adjusts stock-based compensation cost based on its probability assessment. The Company recognizes a cumulative catch up adjustment for changes in its probability assessment in subsequent reporting periods.

Stock-based compensation for employee stock options and ESPP awards are measured on the date of grant using a Black-Scholes option pricing model.

Stock bonus and other liability awards are accounted for as liability-classified awards, because the obligations are based predominantly on fixed monetary amounts that are generally known at the inception of the obligation, to be settled with a variable number of shares of the Company’s common stock.

Awards vest either on a graded schedule or in a lump sum. The Company determines the fair value of each award as a single award and recognizes the expense on a straight-line basis over the service period of the award, which is generally the vesting period. The exercise price of stock options granted is equal to the fair value of the Company’s common stock on the date of grant. Stock options expire ten years from the date of grant.

Comprehensive loss includes all changes in equity that are not the result of transactions with stockholders. The Company’s comprehensive loss consists of its net loss and changes in unrealized gains (losses) from its available-for-sale investments. The Company had no material reclassifications out of accumulated other comprehensive income into net loss in 2020, 2019 ~~2018~~ and ~~2017.~~2018.

The Company may be involved in various lawsuits, claims and proceedings that arise in the ordinary course of business. The Company records a provision for a liability when it believes that it is both probable that a liability has been incurred and the amount can be reasonably estimated. Significant judgment is required to determine both probability and the estimated amount. The Company reviews these provisions at least quarterly and adjusts these provisions to reflect the impact of negotiations, settlements, rulings, and updated information.

In ~~February 2016,~~August 2018, the Financial Accounting Standards Board ~~(FASB)~~("FASB") issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842) (“ASU 2016-02” or “ASC 842”), which requires lessees to record most leases on their balance sheets but recognize the expenses in their statements of operationsfor Implementation Costs Incurred in a ~~manner similar~~Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to current practice. ASU 2016-02 states that a lessee needs to recognize a lease liability for the obligation to make lease payments and a right-to-use(“ROU”) asset for the right to use the underlying asset for the lease term.develop or obtain internal-use software.

The Company adopted ASU ~~2016-02~~2018-15 on January 1, 2020 prospectively. The adoption of ASU 2018-15 did not have a material impact on the Company’s consolidated financial statements.

In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Accounting for Goodwill Impairment (“ASU 2017-04”). ASU 2017-04 removes the requirement to perform a hypothetical purchase price allocation to measure goodwill impairment. A goodwill impairment charge is the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill.

The Company adopted ASU 2017-04 on January 1, 2020 prospectively. The adoption of ASU 2017-04 did not have an impact on the Company’s consolidated financial statements.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 changes the impairment model for most financial assets, and requires the use of an expected loss model in place of the ~~first quarter~~currently used incurred loss method. Under this model, entities are required to estimate the lifetime expected credit loss on such instruments and record an allowance to offset the amortized cost basis of ~~2019,~~the financial asset, resulting in a net presentation of the amount expected to be collected on the financial asset.

The Company adopted ASU 2016-13 on January 1, 2020, utilizing the modified retrospective ~~transition approach through a cumulative-effect adjustment to the opening accumulated deficit balance as of January 1, 2019.~~

~~Refer to Note 8 “Leases” for more information regarding the impact of the~~approach. The adoption of ASU ~~2016-02~~2016-13 did not have a material impact on its consolidated financial statements as credit losses are not expected to be significant based on historical collection trends, the ~~Company’s~~ financial ~~statements.~~ condition of partners and customers, and external market factors.

In August 2020, the FASB issued ASU No. 2020-06, Debt-Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”). ASU 2020-06 simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts in an entity’s own equity. Among other changes, ASU 2020-06 removes the liability and equity separation model for convertible instruments with a cash conversion feature. As a result, after adoption, entities will no longer separately present in equity an embedded conversion feature for such debt. Similarly, the embedded conversion feature will no longer be amortized as interest expense over the life of the instrument. Instead, entities will account for a convertible debt instrument wholly as debt unless 1) a convertible instrument contains features that require bifurcation as a derivative, or 2) a convertible debt instrument was issued at a substantive premium. Among other potential impacts, ASU 2020-06 will reduce reported interest expense,

decrease reported net loss, and result in a reclassification of certain conversion feature balance sheet amounts from stockholder’s equity to liabilities as it relates to the Company’s convertible senior notes. Additionally, ASU 2020-06 requires the application of the if-converted method to calculate the impact of convertible instruments on diluted earnings-per-share, which is consistent with the Company’s accounting treatment under the current accounting guidance. ASU 2020-06 is effective for fiscal years beginning after December 15, 2021, with early adoption permitted for fiscal years beginning after December 15, 2020, and can be adopted on either a fully retrospective or modified retrospective basis.

The Company expects to adopt ASU 2020-06 effective January 1, 2021 using the full retrospective transition method. The Company expects that adoption of ASU 2020-06 will result in accounting of its senior convertible notes as a single unit of account on the balance sheet, and in a decrease of interest expense and net loss. Upon the adoption of ASU 2020-06, interest expense and net loss for 2020 and 2019 will have been reduced by $30,139 and $10,361, respectively. The Company does not expect the adoption of ASU 2020-06 to have any impact on its cash flows from operating, investing or financing activities.

In December 2019, the FASB issued ASU No. ~~2019-02,~~2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”). ASU 2019-12 removes certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. ASU 2019-12 also amends other aspects of the guidance to help simplify and promote consistent application of GAAP. The guidance is effective for interim and annual periods beginning after December 15, 2020, with early adoption permitted. The Company is currently assessing the impact that the adoption of ASU 2019-12 will have on its consolidated financial statements.

~~In August 2018, the FASB issued ASU No. 2018-15,~~ ~~Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract~~ (“ASU 2018-15”). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The update to the standard is effective for interim and annual periods beginning after December 15, 2019, with early adoption permitted. Entities can choose to adopt the ASU 2018-15 prospectively or retrospectively. The Company is currently assessing the impact that the adoption of ASU 2018-15 will have on its consolidated financial statements.

~~In January 2017, the FASB issued ASU No. 2017-04,~~ ~~Intangibles - Goodwill and Other (Topic 350): Simplifying the Accounting for Goodwill Impairment~~ (“ASU 2017-04”). ASU 2017-04 removes the requirement to perform a hypothetical purchase price allocation to measure goodwill impairment. A goodwill impairment charge will be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The update to the standard is effective for interim and annual periods beginning after December 15, 2019, with early adoption permitted, and should be applied prospectively. The Company does not expect the adoption of ASU 2017-04 to have a material impact on its consolidated financial statements.

~~In June 2016, the FASB issued ASU No. 2016-13,~~ ~~Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments~~ (“ASU 2016-13”). ASU 2016-13 changes the impairment model for most financial assets, and requires the use of an expected loss model in place of the currently used incurred loss method. Under this model, entities will be required to estimate the lifetime expected credit loss on such instruments and record an allowance to offset the amortized cost basis of the financial asset, resulting in a net presentation of the amount expected to be collected on the financial asset. The update to the standard is effective for interim and annual periods beginning after December 15, 2019. The Company does not expect the adoption of ASU 2016-13 to have a material impact on its consolidated financial statements.

The core principle of ASC 606 is to recognize revenue to depict the transfer of services or products to customers in an amount that reflects the consideration the Company expects to be entitled to in exchange for those services or products. The Company applies significant judgment in identifying and evaluating any terms and conditions in contracts which may impact revenue recognition. The principle is achieved through the following five-step approach:

The Company generates sales directly through its sales team and, to a growing extent, through its channel partners. Sales to channel partners are made at a discount and revenues are recorded at this discounted price once all revenue recognition criteria are met. Channel partners generally receive an order from an end-customer prior to placing an order with the Company, and these partners do not carry any inventory of the Company’s products or solutions. Payment from channel partners is not contingent on the partner’s success in sales to end-customers. In the event that the Company offers rebates, joint marketing funds, or other incentive programs to a partner, recorded revenues are reduced by these amounts accordingly.

	Year Ended December 31,						Year Ended December 31,
	2019		2018		2017		2020		2019		2018
Subscription service revenue	$	849,267	$	681,138	$	489,274	$	997,506	$	849,267	$	681,138
Subscription software revenue		25,739		23,262		17,081		33,539		25,739		23,262
Hardware and services		13,184		12,594		13,326		18,965		13,184		12,594
Total revenue	$	888,190	$	716,994	$	519,681	$	1,050,010	$	888,190	$	716,994

Subscription service revenue is derived from a subscription-based enterprise licensing model with contract terms typically ranging from one to three years, and consists of (1) subscription fees from the licensing of the Company’s security-as-a-service platform and it’s various components, (2) subscription fees for software with support and related future updates where the software updates are critical to the customers’ ability to derive benefit from the software due to the fast changing nature of the technology. These function together as one performance obligation, and (3) subscription fees for the right to access the Company’s customer support services for software with significant standalone functionality and support services for hardware. The hosted on-demand service arrangements do not provide customers with the right to take possession of the software supporting the hosted services. Support revenue is derived from ongoing security updates, upgrades, bug fixes, and maintenance. A time-elapsed method is used to measure progress because the Company transfers control evenly over the contractual period. Accordingly, the fixed consideration related to subscription service revenue is generally recognized on a straight-line basis over the contract term beginning on the date access is provided, as long as other revenue recognition criteria have been met. Most of the Company’s contracts are non-cancelable over the contract term. Customers typically have the right to terminate their contract for cause if the Company fails to perform in accordance with the contractual terms. Some of the Company’s customers have the option to purchase additional subscription services at a stated price. These options are evaluated on a case-by-case basis but generally do not

provide a material right as they are priced at or above the Company’s SSP and, as such, would not result in a separate performance obligation.

Subscription software revenue is primarily derived from term-based software that is deployed on the customers’ own servers and has significant standalone functionality, is recognized upon transfer of control to the customer. The control for subscription software is transferred at the later of delivery to the customer or the software license start date.

Hardware revenue consists of amounts derived from the sale of the Company’s on-premise hardware appliance, which is recognized upon passage of control, which occurs upon shipment of the product. Professional services revenue consists of fees associated with consulting, implementation and training services for assisting customers in implementing and expanding the use of the Company’s services and products. These services are distinct from subscription, subscription software licenses and hardware. Professional services do not result in significant customization of the Company’s services and products. The Company recognizes revenue related to the professional services as they are performed.

Most of the Company’s contracts with customers contain multiple performance obligations that are distinct and accounted for separately. The transaction price allocated to subscription services and subscription software that does not have significant standalone functionality is determined by considering factors such as historical pricing practices, and the selling price of hardware and professional services is estimated using a cost plus model. The selling price for support of a functional subscription software license is calculated as a percentage of functional subscription software license value which is derived by analyzing internal pricing practice, customer expectations, and industry practice.

Revenue from sales is recorded at the net sales price, which is the transaction price, and includes estimates of variable consideration. The amount of variable consideration that is included in the transaction price is constrained, and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue will not occur when the uncertainty is resolved. If the Company’s services or products do not meet certain service level commitments, the Company’s customers are entitled to receive service credits representing a form of variable consideration. The Company has not historically experienced any significant incidents affecting the defined levels of reliability and performance as required by the Company’s subscription contracts. Accordingly, any estimated refunds related to these contracts in the consolidated financial statements are not material during the periods presented.

Unbilled accounts receivable represents amounts for which the Company has recognized revenue, pursuant to its revenue recognition policy, for software licenses already delivered and professional services already performed, but billed in arrears and for which the Company believes it has an unconditional right to payment. The unbilled accounts receivable balance, included in accounts receivable in the consolidated balance sheet, was $~~3,261~~1,963 and ~~$1,276~~$3,261 as of December 31, ~~2019~~2020 and ~~2018,~~2019, respectively.

The Company capitalizes sales commissions and associated payroll taxes paid to internal sales personnel, and referral fees paid to independent third-parties, that are incremental to the acquisition of customer contracts. These costs are recorded as deferred commissions on the consolidated balance sheets. The Company determines whether costs should be deferred based on its sales compensation plans, if the commissions are incremental and would not have occurred absent the customer contract. Sales commissions for renewal of a subscription contract are not considered commensurate with the commissions paid for the acquisition of the initial subscription contract given

the substantive difference in commission rate between new and renewal contracts. Commissions paid upon the initial acquisition of a contract are amortized over an estimated period of benefit of five years while commissions

paid related to renewal contracts are amortized over a contractual renewal period. Amortization is recognized based on the expected future revenue streams under the customer contracts. Amortization of deferred sales commissions is included in sales and marketing expense in the accompanying consolidated statements of operations. The Company determines the period of benefit for commissions paid for the acquisition of the initial subscription contract by taking into consideration its initial estimated customer life and the technological life of the Company’s software and related significant features. The Company classifies deferred commissions as current or long-term based on the timing of when the Company expects to recognize the expense. The Company periodically reviews these deferred commission costs to determine whether events or changes in circumstances have occurred that could impact the period of benefit of these deferred contract acquisition costs. There were no material impairment losses recorded during the periods presented.

For the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, the Company capitalized $91,763, $80,590 ~~$66,254~~ and ~~$45,910~~$66,254 of commission costs, respectively, and amortized $62,776, $50,415 ~~$37,076~~ and ~~$28,476,~~$37,076, respectively.

Deferred product costs are the incremental costs to fulfill a contract that are directly associated with each non-cancellable customer contract and primarily consist of royalty payments made to third parties, from whom the Company has obtained licenses to integrate certain software into its products. The deferred product costs are recognized based on the contractual term, and included in cost of revenue in the accompanying consolidated statements of operations. The Company classifies deferred product costs as current or long-term based on the timing of when the Company expects to recognize the expense.

For the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, the Company capitalized $5,200, $4,727 ~~$2,765~~ and ~~$2,510~~$2,765 of deferred product costs, respectively, and amortized $4,605, $3,531 ~~$2,463~~ and ~~$2,849,~~$2,463, respectively.

The Company records deferred revenue when cash payments are received, or invoices are issued in advance of the Company’s performance, and generally recognizes revenue over the contractual term. The Company recognized revenue of $608,880, $490,172 ~~$363,483~~ and ~~$242,428~~$363,483 during the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, respectively, that was included in the deferred revenue balances at the beginning of the respective periods.

The Company recognized $1,736, $1,906 ~~$2,901~~ and ~~$1,055~~$2,901 of revenue during the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, respectively, related to the performance obligations satisfied in prior periods. The acquisition of ObserveIT, Ltd. (see Note 3 “Acquisitions”) on November 25, 2019, increased deferred revenue by $6,700, of which $681 was recognized in the year ended December 31, 2019.

Contracted revenue as of December 31, ~~2019~~2020 that has not yet been recognized (“contracted not recognized”) was ~~$676,707,~~$817,949, which includes deferred revenue and non-cancellable amounts that will be invoiced and recognized as revenue in future periods and excludes contracts with an original expected length of one year or less. The Company expects ~~59%~~58% of contracted and not recognized revenue to be recognized over the next twelve months, ~~38%~~40% in years two and three, with the remaining balance recognized thereafter.

Acquisitions are accounted for under the purchase method of accounting in which the tangible and identifiable intangible assets and liabilities of each acquired company are recorded at their respective fair values as of each acquisition date, including an amount for goodwill representing the difference between the respective acquisition consideration and fair values of identifiable net assets. The Company believes that for the acquisitions described below, the combined entities will achieve savings in corporate overhead costs and opportunities for growth through expanded geographic and customer segment diversity with the ability to leverage additional products and capabilities. These factors, among others, contributed to a purchase ~~price~~prices in excess of the estimated fair ~~value~~values of the acquired companies’ net identifiable assets acquired and, as a result, goodwill was recorded in connection with the acquisitions. Goodwill related to the acquisitions of The Defence Works Limited, ObserveIT, Ltd. and Meta Networks, Ltd. is deductible for tax purposes, and goodwill related to the acquisition of Wombat Security Technologies, Inc. is not deductible for tax purposes.

While the Company uses its best estimates and assumptions as part of the purchase price allocation process to value assets acquired and liabilities assumed at the acquisition date, these estimates and assumptions are subject to refinement. When additional information becomes available, such as finalization of negotiations of working capital adjustments and tax related matters, the Company may revise its preliminary purchase price allocation. As a result, during the preliminary purchase price allocation period, which may be up to one year from the acquisition date, the Company may record adjustments to the assets acquired and liabilities assumed, with the corresponding offset to goodwill. Subsequent to the purchase price allocation period, adjustments to assets acquired or liabilities assumed are recognized in the operating results.

On May 5, 2020, the Company completed its acquisition of The Defence Works Limited. The acquisition brings a library of interactive content to the Company’s security awareness training portfolio and provides the Company’s customers innovative content to support their security education programs. The total consideration was $2,767, of which $766 was allocated to goodwill and $2,400 was allocated to intangible assets. The acquired intangible assets consist of content library which is included within the developed technology assets in Note 6 “Goodwill and Intangible Assets.” The impact of the acquisition was not material to the Company’s Consolidated financial statements in 2020.

On November 25, 2019 (the “ObserveIT Acquisition Date”), pursuant to the terms of the share purchase agreement, the Company acquired all shares of ObserveIT, Ltd. (“ObserveIT”). ObserveIT provides detection and prevention from insider threats solutions including data loss detection and response, user activity monitoring, incident response and compliance.

By combining ObserveIT’s endpoint agent technology and data risk analytics with the Company’s information classification, threat detection and intelligence, the Company has an insight into user activity with their sensitive data, wherever it resides, and the ability to immediately remediate risk.

These factors, among others, contributed to a purchase price in excess of the estimated fair value of acquired net identifiable assets and, as a result, goodwill was recorded in connection with the acquisition. The Company has estimated fair values of acquired tangible assets, intangible assets and liabilities at the ObserveIT Acquisition Date. The amounts reported are considered provisional as the Company is completing the valuation work to determine the fair value of certain assets and liabilities acquired, largely with respect to working capital adjustments. The results of operations and the ~~provisional~~ fair values of the acquired assets and liabilities assumed have been included in the accompanying consolidated financial statements since the ObserveIT Acquisition Date.

At the ObserveIT Acquisition Date, the consideration transferred was $213,747, net of cash acquired of $4,752. Of the consideration transferred, $3,250 was held in escrow to secure indemnification obligations, which has not been released as of the issuance of these consolidated financial statements. The revenue from ObserveIT was not material in 2019, and due to the continued integration of the combined businesses, it was impractical to determine the earnings.obligations.

Per the terms of the share purchase agreement, unvested stock options held by ObserveIT employees were canceled and exchanged for the Company’s unvested stock options. The fair value of $446 of these unvested awards

was attributed to pre-combination services and was included in consideration transferred. The fair value of ~~$5,427~~$5,427 was allocated to post-combination services. The unvested awards are subject to the recipient’s continued service with the Company and $5,427 is recognized ratably as stock-based compensation expense over the required remaining service period.

Also, as part of the share purchase agreement, the unvested restricted shares of a certain employee of ObserveIT were exchanged into the right to receive $532 of deferred cash consideration. The unpaid deferred cash consideration iswas presented as restricted cash on the Company’s consolidated balance ~~sheet.~~sheets as of December 31, 2020 and December 31, 2019. The deferred cash consideration of $485 was allocated to post-combination expense and was not included in the purchase price. The deferred cash consideration is subject to forfeiture if employment terminates prior to the lapse of the restrictions, and the fair value is expensed as compensation expense over the three-year vesting period.

The Discounted Cash Flow Method was used to value the acquired developed technology, in-process research and development asset, customer relationships and order backlog. The Relief from Royalty Method was used to value the acquired trade name. Management applied significant judgment in estimating the fair values of these intangible assets, which involved the use of significant assumptions with respect to forecasted revenue, forecasted operating results and discount rates.

The following table summarizes the fair values of tangible assets acquired, liabilities assumed, intangible assets and goodwill:

	Estimated Fair Value			Estimated Useful Life (in years)		Fair Value			Estimated Useful Life (in years)
Current assets	$	10,603		N/A		$	10,603		N/A
Fixed assets		2,132		N/A			2,132		N/A
Operating lease right-of-use asset		2,669		N/A			2,669		N/A
Other assets		652		N/A			652		N/A
Customer relationships		15,800			5		15,800			5
Order backlog		1,300			1		1,300			1
Core/developed technology		35,400			4		35,400			4
Trade name		400			2		400			2
In-process research and development^*		20,600		N/A			20,600		N/A
Operating lease liabilities		(3,317	)	N/A			(3,317	)	N/A
Deferred revenue		(6,700	)	N/A			(6,700	)	N/A
Other liabilities		(5,414	)	N/A			(5,584	)	N/A
Goodwill		144,374		Indefinite			144,544		Indefinite
	$	218,499				$	218,499

*Purchased in-process research and development ~~will be~~was accounted for as an indefinite-lived intangible asset until the underlying project ~~is completed or abandoned.~~was completed.

On May 15, 2019 (the “Meta Networks Acquisition Date”), pursuant to the terms of the share purchase agreement, the Company acquired all shares of Meta Networks, Ltd. (“Meta Networks”), an innovator in zero trust network access.

By combining Meta Networks’ innovative zero trust network access technology with the Company’s people-centric security capabilities the Company ~~expects to make~~made it ~~far~~ simpler for enterprises to precisely control employee and contractor access to on-premises, cloud and consumer applications.

These factors, among others, contributed to a purchase price in excess of the estimated fair value of acquired net identifiable assets and, as a result, goodwill was recorded in connection with the acquisition. The results of operations and the fair values of the acquired assets and liabilities assumed have been included in the accompanying consolidated financial statements since the Meta Networks Acquisition Date.

At the Meta Networks Acquisition Date, the consideration transferred was $104,664, net of cash acquired of $104. Of the consideration transferred, $12,500 was held in escrow to secure indemnification obligations, which has not been released as of the issuance of these consolidated financial statements. The revenue from Meta Networks was not material in 2019, and due to the continued integration of the combined businesses, it was impractical to determine the earnings.

Per the terms of the share purchase agreement, unvested stock options and unvested restricted stock units held by Meta Networks employees were canceled and exchanged for the Company’s unvested stock options and unvested restricted stock units, respectively. The fair value of $184 of these unvested awards was attributed to pre-combination services and was included in consideration transferred. The fair value of $12,918 was allocated to post-combination services. The unvested awards are subject to the recipient’s continued service with the Company, and $12,918 ~~will be~~is recognized ratably as stock-based compensation expense over the required remaining service period.

Also, as part of the share purchase agreement, the unvested restricted shares of certain employees of Meta Networks were exchanged into the right to receive $7,827 of deferred cash consideration and 72 shares of the Company’s common stock that were deferred with the fair value of $8,599. The unpaid deferred cash consideration was presented as restricted cash on the Company’s consolidated balance ~~sheet~~sheets as of December 31, 2020 and December 31, 2019. The deferred cash consideration of $7,596 and the deferred stock of $8,338 (see Note 11 ~~“Equity Award Plans”~~“Stockholders’ Equity”) were allocated to post-combination expense and were not included in the purchase price. The deferred cash consideration and deferred shares are subject to forfeiture if employment terminates prior to the lapse of the restrictions, and their fair value is expensed as compensation and stock-based compensation expense over the three-year vesting period.

The Cost to Recreate Method was used to value the acquired developed technology asset. Management applied judgment in estimating the fair value of this intangible asset, which involved the use of significant assumptions such as the cost and time to build the acquired technology, developer’s profit and rate of return.

The following table summarizes the fair values of tangible assets acquired, liabilities assumed, intangible assets and goodwill:

On February 28, 2018 (the “Wombat Acquisition Date”), pursuant to the terms of the merger agreement, the Company acquired all shares of Wombat Security Technologies, Inc. (“Wombat”), a leader for phishing simulation and security awareness computer-based training. By collecting data from Wombat’s PhishAlarm solution, the Company has access to data on phishing campaigns as seen by non-Company customers, providing broader visibility and insight to the Proofpoint Nexus platform.

With this acquisition, the Company’s customers can leverage the industry’s first solution combining the Company’s advanced threat protection with Wombat’s phishing simulation and computer-based security awareness training. With the combined solutions, the Company’s customers can:

The Company also ~~expects to achieve~~achieved savings in corporate overhead costs for the combined entities. These factors, among others, contributed to a purchase price in excess of the estimated fair value of acquired net identifiable assets and, as a result, goodwill was recorded in connection with the acquisition.

At the Wombat Acquisition Date, the consideration transferred was $225,366, net of cash acquired of $13,452.

Per the terms of the merger agreement, unvested in-the-money stock options held by Wombat employees were canceled and paid off using the same amount per option as for the common share less applicable exercise price for each option. The fair value of $1,580 of these unvested options was attributed to pre-combination service and included in consideration transferred. The fair value of unvested options of $1,571 was allocated to post-combination services and expensed in the three months ended March 31, 2018. Also, as part of the merger agreement, 51 shares of the Company’s common stock were deferred for certain key employees with the total fair value of $5,458 (see Note 11 ~~“Equity Award Plans”~~“Stockholders’ Equity”), which was not included in the purchase price. The deferred shares are subject to forfeiture if employment terminates prior to the lapse of the restrictions, and their fair value is expensed as stock-based compensation expense over the remaining service period.

The following table summarizes the fair values of tangible assets acquired, liabilities assumed, intangible assets and goodwill:

On November 21, 2017 (the “Cloudmark Acquisition Date”), pursuant to the terms of the merger agreement, the Company acquired all shares of Cloudmark, Inc. (“Cloudmark”), a leader in messaging security and threat intelligence for internet service providers and mobile carriers worldwide. As part of the acquisition, Cloudmark’s Global Threat Network was incorporated into Company’s cloud-based Nexus platform, which powers its email, social media, mobile, and SaaS security effectiveness.

The Company believes that with this acquisition, it will benefit from increased messaging threat intelligence from the analysis of billions of daily emails, malicious domain intelligence, and visibility into fraudulent and malicious SMS messages directed to mobile carriers worldwide. The Company also expects to achieve savings in corporate overhead costs for the combined entities. These factors, among others, contributed to a purchase price in excess of the estimated fair value of acquired net identifiable assets and, as a result, goodwill was recorded in connection with the acquisition.

~~At the Cloudmark Acquisition Date, the consideration transferred was $107,283, net of cash acquired of $31,973.~~

Per the terms of the merger agreement, unvested stock options and unvested restricted stock units held by Cloudmark employees were canceled and exchanged for the Company’s unvested stock options and unvested restricted stock units, respectively. The fair value of $91 of these unvested awards was attributed to pre-combination services and included in consideration transferred. The fair value of $1,180 was allocated to post-combination

services. The unvested awards are subject to the recipient’s continued service with the Company, and $1,180 is recognized ratably as stock-based compensation expense over the required remaining service period.

~~The following table summarizes the fair values of tangible assets acquired, liabilities assumed, intangible assets and goodwill:~~

On November 30, 2017 (the “WebLife Acquisition Date”), pursuant to the terms of a merger agreement, the Company acquired all shares of WebLife Balance, Inc. (“WebLife”), a browser isolation offerings vendor, to extend its advanced threat protection capabilities into personal email, while preserving the privacy of its users.

The Company has estimated fair values of acquired tangible assets, intangible assets and liabilities at the WebLife Acquisition Date. The results of operations and the fair values of the acquired assets and liabilities assumed have been included in the accompanying consolidated financial statements since the WebLife Acquisition Date.

~~At the WebLife Acquisition Date, the consideration transferred was $48,765, net of cash acquired of $278.~~

Per the terms of the merger agreement, unvested stock options held by WebLife employees were canceled and exchanged for the Company’s unvested awards. The fair value of $333 of these unvested options was attributed to pre-combination service and included in consideration transferred. The fair value of $1,468 was allocated to post-combination services. The unvested awards are subject to the recipient’s continued service with the Company, and $1,468 is recognized ratably as stock-based compensation expense over the required remaining service period. Also, as part of the merger agreement, 107 shares of the Company’s common stock were deferred for certain key employees with the total fair value of $9,652 (see Note 11 “Equity Award Plans”), which was not included in the purchase price. The deferred shares are subject to forfeiture if employment terminates prior to the lapse of the restrictions, and their fair value is expensed as stock-based compensation expense over the remaining period.

~~The following table summarizes the fair values of tangible assets acquired, liabilities assumed, intangible assets and goodwill:~~

The following unaudited pro forma financial information presents the combined results of operations for the years ended December 31, 2019, 2018 and 2017 as though the acquisitions that occurred during the reporting periods had occurred as of the beginning of the comparable prior annual reporting periods, with adjustments to give effect to pro forma events that are directly attributable to the acquisitions such as amortization expense of acquired intangible assets, stock-based compensation directly attributable to the acquisitions and acquisition-related transaction costs. Accordingly, these unaudited pro forma results are presented for informational purposes only and are not necessarily indicative of what the actual results of operations of the combined company would have been if the acquisitions had occurred at the beginning of the period presented, nor are they indicative of future results of operations:

~~The unaudited pro forma financial information includes acquisition-related transaction costs of $3,294 recorded within operating expenses for the year ended December 31, 2019.~~

Financial instruments that potentially subject the Company to credit risk consist principally of cash and cash equivalents, short-term investments and accounts receivable.

The Company limits its concentration of risk in cash equivalents and short-term investments by diversifying its investments among a variety of industries and issuers and by limiting the average maturity to one year or less. The Company’s professional portfolio managers adhere to this investment policy as approved by the Company’s Board of Directors.

The Company’s investment policy is to invest only in fixed income investments denominated and payable in U.S. dollars. Investment in obligations of the U.S. government and its agencies, money market instruments, commercial paper, certificates of deposit, bankers’ acceptances, corporate bonds of U.S. companies, municipal securities and asset backed securities are allowed. The Company does not invest in auction rate securities, futures contracts, or hedging instruments.

The Company’s accounts receivables are derived from revenue earned from customers primarily located in the United States of America. The Company performs periodic evaluations of its customers’ financial condition and

generally does not require its customers to provide collateral or other security to support accounts receivable, and maintains an allowance for doubtful accounts. Credit losses historically have not been material.

During the year ended December 31, 2019, 2 partners accounted for 12% and 11% of total revenue, respectively. During the years ended December 31, 2018 and 2017, 1 partner accounted for 12% of total revenue in each year. These partners sold to a number of end users, none of which accounted for more than 10% of our total revenue in 2019, 2018 and 2017.

~~NaN partners accounted for 13% and 11% of total accounts receivable, respectively, as of December 31, 2019. NaN partners accounted for 12% of total accounts receivable each as of December 31, 2018.~~

~~Property and equipment at December 31, 2019 and December 31, 2018 consist of the following:~~

Depreciation expense for the years ended December 31, 2019, 2018 and 2017 was $34,684, $32,396, and $23,591, respectively, including depreciation expense for assets under capital leases of $29 and $31 for the years ended December 31, 2018 and 2017, respectively.

~~The allowance for doubtful accounts receivable was not material as of December 31, 2019 and 2018.~~

~~Accrued liabilities at December 31, 2019 and December 31, 2018 consisted of the following:~~

During the year ended December 31, 2020, 2 partners accounted for 13% and 11%, respectively, of total revenue. During the year ended December 31, 2019, 2 partners accounted for 12% and 11%, respectively, of total revenue. During the year ended December 31, 2018, 1 partner accounted for 12% of total revenue. These partners sold to a number of end users, none of which accounted for more than 10% of our total revenue in 2020, 2019 and 2018.

NaN partners accounted for 14% and 11% of total accounts receivable, respectively, as of December 31, 2020. NaN partners accounted for 13% and 11% of total accounts receivable, respectively, as of December 31, 2019.

Property and equipment at December 31, 2020 and December 31, 2019 consist of the following:

Depreciation expense for the years ended December 31, 2020, 2019 and 2018 was $38,460, $34,684, and $32,396, respectively, including depreciation expense for assets under capital leases of $29 for the year ended December 31, 2018.

The allowance for doubtful accounts receivable was not material as of December 31, 2020 and 2019.

Accrued liabilities at December 31, 2020 and December 31, 2019 consisted of the following:

	December 31, 2019							December 31, 2018							December 31, 2020							December 31, 2019
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Developed technology	$	210,469	$	(110,284	)	$	100,185	$	154,069	$	(79,525	)	$	74,544	$	233,469	$	(151,562	)	$	81,907	$	210,469	$	(110,284	)	$	100,185
Customer relationships		87,200		(25,608	)		61,592		71,400		(15,166	)		56,234		87,200		(38,896	)		48,304		87,200		(25,608	)		61,592
Trade names and patents		3,730		(2,349	)		1,381		3,330		(1,430	)		1,900		3,730		(3,549	)		181		3,730		(2,349	)		1,381
Order backlog		8,100		(6,360	)		1,740		6,800		(2,833	)		3,967		8,100		(8,100	)		—		8,100		(6,360	)		1,740
In-process research and development		21,125		—			21,125		—		—			—		—		—			—		21,125		—			21,125
	$	330,624	$	(144,601	)	$	186,023	$	235,599	$	(98,954	)	$	136,645	$	332,499	$	(202,107	)	$	130,392	$	330,624	$	(144,601	)	$	186,023

In-process research and development asset was transferred to developed technology in the second quarter of 2020, as the associated project was completed.

Amortization expense of intangibles totaled $57,505, $45,648 ~~$41,157~~ and ~~$18,506~~$41,157 during the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, respectively.

Future estimated amortization costs of intangible assets as of December 31, ~~2019~~2020 are presented below:

Year Ended December 31,
2020	$	57,990
2021		53,810	$	54,322
2022		31,548		32,060
2023		21,983		22,495
2024		13,686		13,807
2025				6,039
Thereafter		7,006		1,669
	$	186,023	$	130,392

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (i.e., the “exit price”) in an orderly transaction between market participants at the measurement date. A hierarchy for inputs used in measuring fair value has been defined to minimize the use of unobservable inputs by requiring the use of observable market data when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on active market data. Unobservable inputs are inputs that reflect the Company’s assumptions about the assumptions market participants would use in pricing the asset or liability based on the best information available in the circumstances.

The following tables summarize, for each category of assets or liabilities carried at fair value, the respective fair value as of December 31, ~~2019~~2020 and December 31, ~~2018~~2019 and the classification by level of input within the fair value hierarchy:

Based on quoted market prices as of December 31, 2020 and December 31, 2019, the fair value of the 2024 Notes ~~(Note 10)~~(see Note 10 “Convertible Senior Notes” to the Consolidated Financial Statements) was approximately $1,021,200 and $951,050, respectively, determined using Level 2 inputs as they are not actively traded in markets.

The following table represents a reconciliation of the Acquisition-related contingent consideration liability measured at fair value on a recurring basis, using significant unobservable inputs (Level 3):

	Amount			Amount
Balance as of December 31, 2016	$	8,233
Additions during the period		—
Payments during the period		(6,066	)
Adjustments to fair value during the period recorded in General and administrative expenses		(1,533	)
Balance as of December 31, 2017		634		$	634
Additions during the period		—			0
Payments during the period		(555	)		(555	)
Adjustments to fair value during the period recorded in General and administrative expenses		(79	)		(79	)
Balance as of December 31, 2018	$	—		$	0

The carrying amounts of the Company’s cash equivalents, accounts receivable and accounts payable approximate their fair values due to their short maturities.

The cost and fair value of the Company’s cash, cash equivalents and available-for-sale investments as of December 31, ~~2019~~2020 and December 31, ~~2018~~2019 were as follows:

	December 31, 2019									December 31, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value		Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
Cash and cash equivalents:
Cash	$	22,408	$	—	$	—		$	22,408	$	44,355	$	0	$	0	$	44,355
Money market funds		815,158		—		—			815,158		865,924		0		0		865,924
Commercial paper		9,989		—		—			9,989
Total	$	847,555	$	—	$	—		$	847,555	$	910,279	$	0	$	0	$	910,279

Short-term investments:
Corporate debt securities	$	13,453	$	2	$	(1	)	$	13,454
Commercial paper		27,932		—		—			27,932
U.S. Treasury securities		1,998		1		—			1,999
Total	$	43,383	$	3	$	(1	)	$	43,385

	December 31, 2018									December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value		Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Cash and cash equivalents:
Cash	$	39,712	$	—	$	—		$	39,712	$	22,408	$	0	$	0		$	22,408
Money market funds		133,202		—		—			133,202		815,158		0		0			815,158
Commercial paper		12,478		—		—			12,478		9,989		0		0			9,989
Total	$	185,392	$	—	$	—		$	185,392	$	847,555	$	0	$	0		$	847,555

Short-term investments:
Corporate debt securities	$	13,477	$	—	$	(7	)	$	13,470	$	13,453	$	2	$	(1	)	$	13,454
Commercial paper		30,838		—		—			30,838		27,932		0		0			27,932
U.S. Treasury securities		1,999		—		—			1,999		1,998		1		0			1,999
Total	$	46,314	$	—	$	(7	)	$	46,307	$	43,383	$	3	$	(1	)	$	43,385

As of December 31, ~~2019~~2020 and ~~2018,~~2019, all investments mature in less than one year. Fair values for marketable securities are based on quoted market prices for the same or similar instruments.

The Company reviews its investments on a quarterly basis to identify and evaluate investments that have an indication of possible impairment and has determined that 0 other-than-temporary impairments were required to be recognized during the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017.~~2018.

The Company determines if an arrangement is, or contains, a lease at inception. Operating leases are included in operating right-of-use (“ROU”) assets and operating lease liabilities in the consolidated balance sheets. The Company does not separate non-lease components from lease components for its real estate and data center leases and instead account for each separate lease component, and non-lease components associated with that lease component, as a single lease component. The Company does not recognize right-of-use assets and lease liabilities for short-term leases, which have a lease term of twelve months or less.

The Company adopted ASC 842 in the first quarter of 2019, utilizing the modified retrospective transition method through a cumulative-effect adjustment to the opening accumulated deficit as of January 1, 2019.

ROU assets represent the Company’s right to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments based on the lease contracts. Operating lease ROU assets and liabilities were recognized at adoption date, or lease commencement date if the commencement date was after January 1, 2019, based on the present value of lease payments over the remaining lease term. The Company’s lease contracts do not provide an implicit rate, as such the Company used its incremental borrowing rate based on

the information available at adoption date, or lease commencement date if the commencement date was after January 1, 2019, in determining the present value of lease payments. The operating lease ROU assets also includes any lease payments made to the lessors at or before the lease commencement date, and excludes lease incentives. The lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense is recognized on a straight-line basis over the lease term.

The Company has operating leases for corporate offices, research and development facilities, sales and marketing offices and data centers.

The ~~Company adopted ASC 842~~ ~~in the first quarter of 2019, utilizing the modified retrospective transition approach through a cumulative-effect adjustment to the opening accumulated deficit as of January 1, 2019.~~ ~~The Company continues to report the comparative periods presented in the period of adoption under ASC 840.~~

~~The~~ Company’s real estate leases have remaining lease terms for ~~one~~up to ~~ten~~eleven years, some of which include options to extend the lease period up to ten years. The data center leases have remaining lease terms of ~~one year~~up to three years, some of which have renewal periods of one year.

In October 2018, the Company entered into a 127-month lease agreement to lease approximately 242,400 square feet of corporate office space in Sunnyvale, California, which ~~is expected to become~~became the Company’s new corporate headquarters ~~beginning~~ in ~~2020. The~~November 2020, after the construction of the property ~~will be constructed~~ by the landlord ~~with the completion date expected to occur between August~~was completed and ~~November 2020, which is when~~ the lease ~~is expected to commence. As such, 0 ROU assets or related lease liabilities were recorded in the financial statements in 2019.~~commenced. The lease contains a rent holiday period, scheduled rent increases, lease incentives, and renewal option which allow the lease term to be extended by five years. Base rental payments will be approximately ~~$161,300~~$160,178 over the lease term.

~~Premises rent expense was $10,944 and $8,010 for the years ended December 31, 2018 and 2017, respectively.~~

As previously disclosed in the Company’s 2018 Annual Report on Form 10-K and under ASC-840, future minimum lease payments for operating leases having initial or remaining noncancelable lease terms in excess of one year as of December 31, 2018 were as follows:

As of December 31, ~~2019,~~2020, the Company’s minimum purchase commitments for products and services were ~~$100,215,~~$57,217, of which ~~$58,137~~$16,411 represent long-term purchase commitments through the year ending December 31, ~~2023.~~2025.

Under the indemnification provisions of the Company’s customer agreements, the Company agrees to indemnify and defend and hold harmless its customers against, among other things, infringement of any patent, trademark or copyright under any country’s laws or the misappropriation of any trade secret arising from the customers’ legal use of the Company’s solutions. The exposure to the Company under these indemnification provisions is generally limited to the total amount paid by the customers under the applicable customer agreement. However, certain indemnification provisions potentially expose the Company to losses in excess of the aggregate amount paid to the Company by the customer under the applicable customer agreement. To date, there have been no claims against the Company or its customers pursuant to these indemnification provisions.

From time to time, the Company may be involved in legal proceedings and subject to claims in the ordinary course of business. For lawsuits where the Company is the defendant, the Company is in the process of defending these litigation matters, and while there can be no assurances and the outcomes of these matters are currently not determinable, the Company currently believes that there are no existing claims or proceedings that are likely to have a material adverse effect on the Company’s financial position, results of operations or cash flows.

On August 23, 2019, the Company issued $920,000 aggregate principal amount of 0.25% Convertible Senior Notes due 2024 (the “2024 Notes”). The offering represented $800,000 aggregate principal amount of the 2024 Notes plus the full exercise of the initial buyers’ option to purchase up to an additional $120,000 aggregate principal amount. The net proceeds after the agent’s discount and issuance costs of $19,065 from the 2024 Notes offering were approximately $900,935. The Company used $84,871 of the net proceeds from the offering to pay the cost of the capped call transactions described below. The Company expects to use the remaining net proceeds for general corporate purposes, which may include acquisitions or other strategic transactions. The 2024 Notes are senior unsecured, unsubordinated obligations of the Company. The 2024 Notes bear interest at 0.25% per year, payable semi-annually in arrears every February 15 and August 15, beginning on February 15, 2020. The 2024 Notes mature on August 15, 2024, unless repurchased, redeemed or converted in accordance with their terms prior to such date.

The initial conversion rate is 6.4941 shares of the Company’s common stock per $1 principal amount of the 2024 Notes, which equates to an initial conversion price of $153.99 per share of common stock. Throughout the term of the 2024 Notes, the conversion rate may be adjusted upon the occurrence of certain events.

At the Company’s option, on or after August 20, 2022, the Company will be able to redeem all or a portion of the 2024 Notes at 100% of the principal amount, plus any accrued and unpaid interest, under certain conditions. The Company may redeem the 2024 Notes in shares of the Company’s common stock, cash, or some combination of each.

Prior to April 15, 2024, the 2024 Notes will be convertible at the option of the holders only upon the satisfaction of certain conditions and during certain periods upon the following circumstances:

On or after April 15, 2024, holders may convert their 2024 Notes at the applicable conversion rate at any time prior to the close of business on the second scheduled trading day immediately preceding the maturity date.

Holders of the 2024 Notes also have the right to require the Company to repurchase all or a portion of the 2024 Notes at 100% of the principal amount, plus accrued and unpaid interest, if any, upon the occurrence of certain fundamental changes to the Company.

In accounting for the issuance of the 2024 Notes, the Company separated the 2024 Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of similar liabilities that do not have associated convertible features. The carrying amount of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the principal amount of the 2024 Notes. The Company bifurcated the conversion option of the 2024 Notes from the debt instrument, classified the conversion option in equity and ~~will accrete~~accretes the resulting debt discount as interest expense over the contractual term of the 2024 Notes using the effective interest rate method. The equity component is not remeasured while the 2024 Notes continue to meet the conditions for equity classification. Upon issuance of the 2024 Notes, after allocation of debt discount and issuance costs, the Company recorded $737,912 as debt and $163,023 as additional paid in capital within stockholders’ equity.

The effective interest rate of the liability component of the 2024 Notes is 4.76%. This interest rate was based on the interest rates of similar liabilities held by other companies with similar credit risk ratings at the time of issuance that did not have associated convertible features.

The debt discount and issuance costs were allocated based on the total amount incurred to the liability and equity components using the same proportions as the proceeds from the 2024 Notes. The equity issuance costs of $3,450 were recorded as a decrease to additional paid-in capital at the issuance date.

The following table represents the carrying value of the 2024 Notes as of December 31, 2020 and December 31, 2019:

	December 31, 2019			December 31, 2018		December 31, 2020			December 31, 2019
Liability component:
Principal	$	920,000		$	—	$	920,000		$	920,000
Less: debt discount and issuance costs, net of amortization		(170,380	)		—		(136,439	)		(170,380	)
Net carrying amount	$	749,620		$	—	$	783,561		$	749,620
Equity component (1)	$	163,023		$	—	$	163,023		$	163,023

(1) Recorded on the consolidated balance sheets as additional paid-in capital, net of the $3,450 issuance costs in equity.

In connection with the issuance of the 2024 Notes, including the initial purchasers’ exercise of the option to purchase additional 2024 Notes, the Company entered into privately negotiated capped call transactions with certain counterparties (the “Capped Calls”). The Capped Calls are expected to reduce potential dilution to the Company’s common stock upon conversion of the 2024 Notes and/or offset any cash payments that the Company is required to make in excess of the principal amount of the converted 2024 Notes, as the case may be, with such reduction and/or offset subject to a cap. The Capped Calls have a cap price equal to $223.98 per share, subject to certain adjustments, and expire on August 15, 2024. The Capped Calls are subject to adjustment upon the occurrence of specified extraordinary events affecting the Company, including merger events, tender offers and announcement events. In addition, the Capped Calls are subject to certain specified additional disruption events that may give rise to a termination of the Capped Calls, including nationalization, insolvency or delisting, changes in law, failures to deliver, insolvency filings and hedging disruptions.

For accounting purposes, the Capped Calls are separate transactions, and not part of the terms of the 2024 Notes. As these transactions meet certain accounting criteria, the Capped Calls are recorded in stockholders’ equity and are not accounted for as derivatives. The premium paid for the purchase of the Capped Calls in the amount of $83,720 and related issuance cost of $1,151 have been recorded as a reduction to additional paid-in capital and will not be remeasured.

On June 17, 2015, the Company issued $200,000 principal amount of 0.75% Convertible Senior Notes (the “2020 Notes”) due 2020 in a private offering to qualified institutional buyers (“Holders”) pursuant to Rule 144A under the Securities Act of 1934, as amended (the “Securities Act”). The initial Holders of the 2020 Notes also had an option to purchase an additional $30,000 in principal amount which was exercised in full. The net proceeds after the agent’s discount and issuance costs of $6,581 from the 2020 Notes offering were approximately $223,419. The Company used the net proceeds for working capital and general corporate purposes, which included funding the Company’s operations, capital expenditures, and acquisitions of businesses, products or technologies. The 2020 Notes bore interest at 0.75% per year, payable semi-annually in arrears every June 15 and December 15, beginning on December 15, 2015.

During the quarter ended September 30, 2018, $229,869 of the principal amount of the 2020 Notes was converted into 2,928 shares of common stock, with the remaining $142 repaid in cash. The shares of common stock had a fair value of $336,994 at the time of the conversion. This transaction resulted in a $7,207 loss on extinguishment that was included in interest expense in the Consolidated Statement of Operations. The loss on extinguishment was calculated as the difference between the fair value amount allocated to the liability component on the date of conversion and net carrying amount of the liability component.

~~On December 11, 2013,~~For the Company issued $175,000 principal amount of 1.25% Convertible Senior Notes due 2018 (the “2018 Notes,” and together with the 2020 Notes and 2024 Notes, the “Notes”) in a private offering to Holders pursuant to Rule 144A under the Securities Act. The initial Holders of the 2018 Notes also had an option to purchase an additional $26,250 in principal amount which was exercised in full. The net proceeds after the agent’s discount and issuance costs of $5,803 from the 2018 Notes offering were approximately $195,446. The Company used the net proceeds for working capital and general corporate purposes, which included funding the Company’s operations, capital expenditures, and acquisitions of businesses, products or technologies believed to be of strategic importance. The 2018 Notes bore interest at 1.25% per year, payable semi-annually in arrears every June 15 and December 15, beginning on June 15, 2014.

~~During the year~~years ended December 31, ~~2017, $201,250 of~~2020, 2019 and 2018, the ~~principal amount of~~Company incurred the 2018 Notes was converted into 5,159 shares of common stock, with the remaining $14 paid in cash. The shares of common stock had a fair value of $473,176 at the time of the conversion. This resulted in a $2,696following interest expense and loss on ~~extinguishment that was included in interest expense in the Consolidated Statement of Operations. The loss on extinguishment was calculated as the difference between the fair value amount allocated~~conversion related to the ~~liability component and net carrying amount of the liability component.~~Notes:

~~For the years ended December 31, 2019, 2018 and 2017, the Company incurred the following interest expense and loss on conversion related to the Notes:~~

On March 30, 2012, the Company’s Board of Directors (the “Board of Directors”) and the Company’s stockholders approved the 2012 Equity Incentive Plan (the “2012 Plan”), which became effective in April 2012. The 2012 Plan was amended, effective June 2019, when the Company’s stockholders approved an Amended and Restated 2012 Equity Incentive Plan (the “Amended 2012 Plan”) at the annual meeting of the stockholders on June 6, 2019. The Company has 8 equity incentive plans: the Company’s 2002 stock option plan (the “2002 Plan”), the 2012 Plan and 6 plans assumed by the Company upon various business acquisitions. The assumed plans are the Cloudmark, Inc. plan, the WebLife Balance, Inc. plan, the Meta ~~Network~~Networks, Ltd. plan, the ObserveIT, Ltd. plan, and 2 FireLayers, Ltd. (“FireLayers”) plans. Upon the Company’s initial public offering, all shares that were reserved under the 2002 Plan but not issued, and shares issued but subsequently returned to the plan through forfeitures, cancellations and repurchases became part of the 2012 Plan and no further shares will be granted pursuant to the 2002 Plan. No further shares will be granted pursuant to the assumed plans. All outstanding stock awards under the 2002 Plan, the assumed plans and Amended 2012 Plan will continue to be governed by their existing terms. Under the Amended 2012 Plan, the Company has the ability to issue incentive stock options (“ISOs”), nonstatutory stock options (“NSOs”), restricted stock awards, stock bonus awards, stock appreciation rights (“SARs”), restricted stock units (“RSUs”), and performance stock units (“PSUs”). The Amended 2012 Plan also allows direct issuance of common stock to employees, outside directors and consultants at prices equal to the fair market value at the date of grant of options or issuance of common stock. Additionally, the Amended 2012 Plan provides for the grant of performance cash awards to employees, directors and consultants. The Company has the right to repurchase any unvested shares (at the option exercise price) of common stock issued directly or under option exercises. The right of repurchase generally expires over the vesting period.

Under the equity incentive plans, the term of an option grant shall not exceed ten years from the date of its grant and options generally vest over a three to four-year period, with vesting on a monthly or annual interval. Under the 2002 Plan and the Amended 2012 Plan, 32,759 shares of common stock are reserved for issuance to eligible participants. As of December 31, ~~2019, 7,162~~2020, 6,575 shares were available for future grant. Restricted stock awards generally vest over a ~~four-year~~three to five -year period.

The Company net-share settles equity awards held by employees by withholding shares upon vesting to satisfy tax withholding obligations. The shares withheld to satisfy employee tax withholding obligations are returned to the Company’s Amended 2012 Plan and will be available for future issuance. Payments for employee’s tax obligations to the tax authorities are recognized as a reduction to additional paid-in capital and reflected as financing activities in the Company’s consolidated statements of cash flows.

The fair value of options granted is estimated on the grant date using the Black-Scholes option valuation model. This valuation model for stock-based compensation expense requires the Company to make assumptions and judgments about the variables used in the calculation, including the expected term (weighted-average period of time that the options granted are expected to be outstanding), the volatility of the common stock price and the assumed risk-free interest rate. The Company accounts for forfeitures as they occur.

NaN options were granted during the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017.~~ 2018.

	Shares subject to Options Outstanding										Shares subject to Options Outstanding
	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)			Aggregate Intrinsic Value		Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Balance at December 31, 2016		3,183		$	18.91		5.39		$	164,842
Options assumed per business acquisitions		13			20.27
Options exercised		(1,126	)		11.04
Options forfeited and canceled		(30	)		45.54
Balance at December 31, 2017		2,040			22.88		5.17		$	134,511		2,040		$	22.88		5.17	$	134,511
Options exercised		(767	)		12.78							(767	)		12.78
Options forfeited and canceled		(18	)		49.24							(18	)		49.24
Balance at December 31, 2018		1,255			28.67		4.77		$	69,224		1,255			28.67		4.77	$	69,224
Options assumed per business acquisitions		91			11.77							91			11.77
Options exercised		(297	)		17.00							(297	)		17.00
Options forfeited and canceled		(2	)		13.46			��				(2	)		13.46
Balance at December 31, 2019		1,047		$	30.55		4.38		$	88,190		1,047			30.55		4.38	$	88,190
Exercisable, December 31, 2019		957		$	31.75		4.03		$	79,448
Vested and expected to vest, December 31, 2019		1,047		$	30.55		4.38		$	88,190
Options exercised												(221	)		20.81
Options forfeited and canceled												(5	)		18.32
Balance at December 31, 2020												821		$	33.25		3.56	$	84,699
Exercisable, December 31, 2020												782		$	34.24		3.38	$	79,932
Vested and expected to vest, December 31, 2020												821		$	33.25		3.56	$	84,699

The Company realized no income tax benefit from stock option exercises in each of the periods presented due to recurring losses and the valuation allowances for deferred tax assets.

The total intrinsic value of options exercised was $20,640, $30,766 ~~$73,057~~ and ~~$82,131~~$73,057 for the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, respectively. Total cash proceeds from such option exercises were $4,598, $5,048 ~~$9,802~~ and ~~$12,383~~$9,802 for the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, respectively.

The grant date fair value of options that vested was $4,303, $1,373 ~~$3,447~~ and ~~$7,450~~$3,447 during the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, respectively.

As of December 31, ~~2019,~~2020, the Company had unrecognized stock-based compensation expense of ~~$8,594~~$3,908 related to stock options that will be recognized, over the average remaining vesting term of the options of ~~1.97~~1.39 years.

	RSUs and PSUs Outstanding					RSUs and PSUs Outstanding
	Number of Shares			Granted Fair Value Per Unit		Number of Shares			Granted Fair Value Per Unit
Awarded and unvested at December 31, 2016		3,465		$	56.11
Awards assumed per business acquisition		8			91.10
Awards granted		1,865			84.91
Awards vested		(1,320	)		52.36
Awards forfeited		(478	)		63.44
Awarded and unvested at December 31, 2017		3,540			71.77		3,540		$	71.77
Awards granted		3,209			101.56		3,209			101.56
Awards vested		(1,446	)		69.50		(1,446	)		69.50
Awards forfeited		(735	)		93.70		(735	)		93.70
Awarded and unvested at December 31, 2018		4,568			89.88		4,568			89.88
Awards assumed per business acquisition		75			119.13		75			119.13
Awards granted		2,228			118.30		2,228			118.30
Awards vested		(1,546	)		87.98		(1,546	)		87.98
Awards forfeited		(430	)		94.33		(430	)		94.33
Awarded and unvested at December 31, 2019		4,895		$	103.48		4,895			103.48
Awards granted							1,554			102.92
Awards vested							(1,718	)		97.69
Awards forfeited							(349	)		107.80
Awarded and unvested at December 31, 2020							4,382		$	105.21

As of December 31, ~~2019,~~2020, there was ~~$383,227~~$319,217 of unamortized stock-based compensation expense related to unvested RSUs, which are expected to be recognized over a weighted average period of ~~3.38~~3.19 years.

The Company granted 158 shares, 171 shares ~~474 shares~~ and ~~177~~474 shares of PSUs in the years ended December 31, 2020, 2019 and 2018, ~~and 2017,~~ respectively. The Company also granted 11 restricted performance-based shares in the year ended December 31, 2020. The PSU vesting conditions were based on individual performance targets. Unamortized stock-based compensation expense for PSUs expected to vest was ~~$32,025~~$1,049 as of December 31, ~~2019.~~2020.

The total accrued liability for the stock bonus awards and other liability awards was ~~$13,427~~$12,480 and ~~$12,741~~$13,427 as of December 31, ~~2019~~2020 and ~~2018,~~2019, respectively.

During the years ended December 31, 2020, 2019 and 2018, ~~and 2017,~~125 shares, 107 shares ~~61 shares~~ and 8561 shares of common stock earned under the stock bonus program were issued. Stock-based compensation expense related to stock bonus program were $12,480, $13,427 ~~$12,701~~ and ~~$6,616,~~$12,701, respectively, for the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017.~~2018.

In March 2015, the Company issued liability awards with a fair value of $6,885, which vested over three years period and were subject to continuous service and other conditions. The liability awards were settled with a variable number of shares of the Company’s common stock. During the years ended December 31, 2018, ~~and 2017,~~ 20 ~~and 29~~ shares were vested and ~~issued, respectively.~~issued. The Company recognized $408 ~~and $2,293~~ of stock-based compensation expense related to these liability awards in the years ended December 31, ~~2018 and 2017.~~2018. There ~~are~~ were 0 outstanding liability awards as of December 31, 2018.

On March 30, 2012, the Board of Directors and the Company’s stockholders approved the 2012 Employee Stock Purchase Plan (the “ESPP”), which became effective in April 2012. A total of 745 shares of the Company’s common stock were initially reserved for future issuance under the ESPP. The number of shares reserved for issuance under the ESPP will increase automatically on January 1 of each of the first eight years commencing with 2013 by the number of shares equal to 1% of the Company’s shares outstanding on the immediately preceding December 31, but not to exceed 1,490 shares, unless the Board of Directors, in its discretion, determines to make a

smaller increase. As of December 31, ~~2019,~~2020, there were ~~2,165~~2,410 shares of the Company’s common stock available for future issuance under the ESPP.

The fair value of the option component of the ESPP shares was estimated at the grant date using the Black-Scholes option pricing model with the following weighted average assumptions:

	Year ended December 31,			Year ended December 31,
	2019	2018	2017	2020	2019	2018
Expected life (in years)	0.5	0.5	0.5	0.5	0.5	0.5
Volatility	36% - 37%	33% - 40%	29% - 37%	36% - 53%	36% - 37%	33% - 40%
Risk-free interest rate	1.58 - 2.43%	1.76% - 2.50%	0.76% - 1.16%	0.10% - 0.15%	1.58% - 2.43%	1.76% - 2.50%
Dividend yield	—%	—%	—%	—%	—%	—%

The Company issued 323 shares, 266 shares ~~231 shares~~ and ~~183~~231 shares under the ESPP in the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, respectively, at a weighted average exercise price per share of $91.67, $86.51, ~~$77.02,~~ and ~~$73.02,~~$77.02, respectively. As of December 31, ~~2019,~~2020, the Company expects to recognize ~~$3,531~~$4,007 of the total unamortized compensation cost related to employee purchases under the ESPP over a weighted average period of 0.37 years.

As part of the FireLayers acquisition, the Company granted 111 shares of restricted stock in 2016 to certain key employees with a total fair value of $8,669 with annual vesting term of three years. The Company recognized $2,349 ~~$2,887~~ and $2,887 of stock-based compensation expense in 2019 ~~2018~~ and ~~2017,~~2018, respectively. They are considered issued and outstanding shares of the Company at the grant date and have the same rights as other shares of common stock. As of December 31, 2019, all shares were vested.

As part of the Weblife acquisition, 107 shares were deferred for certain key employees with the total fair value of $9,652, and a vesting period between three and four years. The Company recognized ~~$2,415,~~$2,421, $2,415 and ~~$205~~$2,415 of stock-based compensation in the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, respectively. As of December 31, ~~2019,~~2020, there was ~~$4,617~~$2,196 of unamortized stock-based compensation expense related to the unvested deferred shares. The deferred shares are subject to forfeiture if employment terminates prior to the lapse of the deferral date, and are expensed over the vesting period.

As part of the Wombat acquisition, 51 shares were deferred for certain key employees with the total fair value of $5,458, and a vesting period of two years. The Company recognized ~~$2,788~~$382 and ~~$2,288~~$2,788 of stock-based compensation in the years ended December 31, ~~2019~~2020 and ~~2018,~~2019, respectively. As of December 31, ~~2019, there was $382 of unamortized stock-based compensation expense related to the unvested deferred shares. The deferred~~2020, all shares ~~are subject to forfeiture if employment terminates prior to the lapse of the deferral date, and are expensed over the vesting period.~~were vested.

As part of the Meta Networks acquisition in 2019, 72 shares were deferred for certain key employees with the total fair value of $8,338 allocated to post-combination expense, and a vesting period of three years. The Company recognized $2,782 and $1,748 of stock-based compensation in the year ended December 31, ~~2019.~~2020 and 2019, respectively. As of December 31, ~~2019,~~2020, there was ~~$6,590~~$3,808 of unamortized stock-based compensation expense related to the unvested deferred shares. The deferred shares are subject to forfeiture if employment terminates prior to the lapse of the deferral date and are expensed over the vesting period. They are considered issued and outstanding shares of the Company at the acquisition date and have the same rights as other shares of common stock.

On August 27, 2020, the board of directors approved a share repurchase program under which the Company is authorized to repurchase up to $300,000 of the Company’s common stock (the “Repurchase Program”). Repurchases under the Repurchase Program may be made through open market purchases (including through trading plans administered under pre-determined purchasing criteria), block trades and/or privately negotiated transactions, subject to market conditions, applicable legal requirements, and other relevant factors. The timing, volume and nature of the repurchases are at the discretion of management, based on its evaluation of the capital needs of the Company, market conditions, applicable legal requirements and other factors. The Repurchase Program.

does not have an expiration date and may be suspended or discontinued by the Company at any time without prior notice.

During the year ended December 31, 2020, the Company repurchased 1,335 shares of common stock under the Repurchase Program in open market transactions at an average price of $104.42 per share, for an aggregate purchase price of $139,356. As of December 31, 2020, $160,644 remained available for future share repurchases under the Repurchase Program.

Basic net loss per share of common stock is calculated by dividing the net loss by the weighted‑average number of shares of common stock outstanding for the period. The weighted‑average number of shares of common stock used to calculate basic net loss per share of common stock excludes those shares subject to repurchase related to stock options or restricted stock that were exercised or issued prior to vesting as these shares are not deemed to be issued for accounting purposes until they vest. Diluted net loss per share of common stock is computed by dividing the net loss using the weighted‑average number of shares of common stock, excluding common stock subject to repurchase, and, if dilutive, potential shares of common stock outstanding during the period. Basic and diluted net

loss per common share was the same for all periods presented as the impact of all potentially dilutive securities outstanding was anti-dilutive.

The following table presents the potentially dilutive common shares outstanding that were excluded from the computation of diluted net loss per share of common stock for the periods presented because including them would have been anti-dilutive:

	December 31,						December 31,
	2019		2018		2017		2020		2019		2018
Stock options to purchase common stock		1,047		1,255		2,040		821		1,047		1,255
Restricted stock units		4,895		4,568		3,540		4,382		4,895		4,568
Employee stock purchase plan		157		163		118		214		157		163
Common stock subject to repurchase		207		195		90		119		207		195
Stock bonus awards and other liability awards		117		152		98		91		117		152
2024 Notes		5,975		—		—		5,975		5,975		—
2020 Notes		—		—		2,831
Total		12,398		6,333		8,717		11,602		12,398		6,333

Operating segments are reported in a manner consistent with the internal reporting supported and defined by the components of an enterprise about which separate financial information is available, provided and is evaluated regularly by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is its Chief Executive Officer. The Company’s Chief Executive Officer reviews financial information presented on a consolidated basis. The Company has 1 business activity, and there are no segment managers who are held accountable for operations, operating results and plans for levels or components below the consolidated unit level. Accordingly, the Company determined that it has 1 operating and reportable segment.

The following sets forth total revenue by geographic area. Revenue by geographic area is based upon the billing address of the customer:

	Year Ended December 31,						Year Ended December 31,
	2019		2018		2017		2020		2019		2018
Total revenue by geographic area:
United States	$	713,305	$	584,294	$	432,564	$	832,034	$	713,305	$	584,294
Rest of world		174,885		132,700		87,117		217,976		174,885		132,700
Total revenue	$	888,190	$	716,994	$	519,681	$	1,050,010	$	888,190	$	716,994

The domestic and foreign components of loss before income taxes were as follows for the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017:~~2018:

	Year Ended December 31,									Year Ended December 31,
	2019			2018			2017			2020			2019			2018
Domestic	$	(142,830	)	$	(126,128	)	$	(110,192	)	$	(185,553	)	$	(142,830	)	$	(126,128	)
Foreign		32,482			9,147			30,440			54,664			32,482			9,147
Loss before income taxes	$	(110,348	)	$	(116,981	)	$	(79,752	)	$	(130,889	)	$	(110,348	)	$	(116,981	)

The ~~(provision for) benefit from~~provision for (benefit from) income taxes is comprised of:

	Year Ended December 31,									Year Ended December 31,
	2019			2018			2017			2020			2019			2018
Current tax expense:
Federal	$	—		$	—		$	—		$	0		$	0		$	0
State		258			258			80			134			258			258
Foreign		22,030			1,768			5,923			34,768			22,030			1,768
Total current		22,288			2,026			6,003			34,902			22,288			2,026
Deferred tax expense:
Federal		264			(12,773	)		(12,268	)		182			264			(12,773	)
State		—			(1,812	)		(266	)		—			—			(1,812	)
Foreign		(2,635	)		(673	)		(3,419	)		(2,164	)		(2,635	)		(673	)
Total deferred		(2,371	)		(15,258	)		(15,953	)		(1,982	)		(2,371	)		(15,258	)
Provision for (benefit from) income taxes	$	19,917		$	(13,232	)	$	(9,950	)	$	32,920		$	19,917		$	(13,232	)

~~As the result of adopting ASU 2016-09, the Company recorded excess tax benefits on a prospective basis starting January 1, 2017, resulting~~97

(dollars and share amounts in ~~a cumulative-effect adjustment recorded in consolidated statements of stockholders’ equity in 2017.~~ thousands, except per share amounts)

The reconciliation of income tax expense (benefit) to the income tax provision (benefit) included in the consolidated statements of operations at the statutory federal income tax rate of 21% for the year ended December 31, 2020, 2019 and 2018 ~~and 34% for the years ended December 31, 2017~~ is as follows:

	Year Ended December 31,									Year Ended December 31,
	2019			2018			2017			2020			2019			2018
Tax at federal statutory rate	$	(23,173	)	$	(24,566	)	$	(27,116	)	$	(27,487	)	$	(23,173	)	$	(24,566	)
Foreign income tax rate differential		717			307			(3,076	)		1,058			717			307
State, net of federal benefit		(4,939	)		(3,859	)		(2,942	)		(6,401	)		(4,939	)		(3,859	)
Stock compensation charges		(11,265	)		(20,341	)		(32,150	)		(2,903	)		(11,265	)		(20,341	)
SubPart F and other permanent items		9,657			1,597			2,155			9,734			9,657			1,597
Section 162m		8,465			5,501			601			1,614			8,465			5,501
Provision to return and other		(453	)		(1,082	)		2,480			2,249			(453	)		(1,082	)
Research and development credits		(21,413	)		(11,165	)		(7,713	)		(15,525	)		(21,413	)		(11,165	)
Uncertain tax positions		16,110			2,171			5,888			20,353			16,110			2,171
Impact of Tax Act and other tax law changes		(42	)		—			85,606			31			(42	)		0
Valuation allowance		46,253			38,205			(33,683	)		50,197			46,253			38,205
Provision for (benefit from) income taxes	$	19,917		$	(13,232	)	$	(9,950	)	$	32,920		$	19,917		$	(13,232	)

Deferred tax assets and liabilities reflect the net tax effects of net operating loss and tax credit carryovers and the temporary differences between the carrying amount of assets and liabilities for financial reporting and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets were as follows:

	At December 31,						At December 31,
	2019			2018			2020			2019
Deferred tax assets:
Net operating loss carryforwards	$	215,365		$	192,508		$	213,137		$	215,365
Tax credit carryforwards		49,300			33,799			61,165			49,300
Research expenditures		12,139			577			8,612			12,139
Deferred revenue		16,254			17,716			41,139			16,254
Stock compensation		20,156			16,861			23,860			20,156
Fixed assets		1,345			313			191			1,345
Intangible assets								37			—
Operating lease liabilities								47,791			10,645
Accruals and other		13,753			12,619			12,369			3,108
Gross deferred tax assets		328,312			274,393			408,301			328,312
Valuation allowance		(224,047	)		(222,734	)		(274,244	)		(224,047	)
Total deferred tax assets		104,265			51,659			134,057			104,265
Deferred tax liabilities:
Intangible assets and other		(26,203	)		(23,282	)		(418	)		(16,486	)
Fixed assets								(5,037	)		—
Deferred commissions		(33,263	)		(26,008	)		(40,896	)		(33,263	)
Convertible senior notes		(42,304	)		—			(34,761	)		(42,304	)
Operating leases assets								(42,070	)		(9,717	)
Other								(6,615	)		—
Total deferred tax liabilities		(101,770	)		(49,290	)		(129,797	)		(101,770	)
Total net deferred tax assets (liabilities)	$	2,495		$	2,369
Total net deferred tax assets							$	4,260		$	2,495
Non-current deferred income tax assets (included in other long-term assets)	$	3,721		$	2,946		$	5,639		$	3,721
Non-current deferred income tax liabilities (included in long-term liabilities)	$	1,226		$	577		$	1,379		$	1,226

The Company records net deferred tax assets to the extent that Company believes these assets will more likely than not be realized. In making such determination, the Company considers all available positive and negative

evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax planning strategies and recent financial operations.

Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. The valuation allowance increased by $50,197, $1,313 ~~$41,521~~ and ~~$50,056~~$41,521 during the years ended December 31, 2020, 2019 ~~2018~~ and ~~2017,~~2018, respectively. The change in valuation allowance for the year ended December 31, 2018, included an increase of $3,392 related to the 2020 Notes conversion. The change in valuation allowance for the year ended December 31, 2019, included a decrease of $44,855 related to the 2024 Notes issued in August 2019.

During the three months ended March 31, 2017, the Company transferred certain intellectual property rights from its wholly owned subsidiary in Israel to the United States. Although the transfer of intellectual property rights between consolidated entities did not result in any gain in the consolidated statements of operations, the transfer did result in a taxable gain in Israel. In the Company’s financial statements ending before January 1, 2018, taxes incurred related to the intercompany transaction have been treated as a prepaid tax asset in the Company’s consolidated balance sheet and were being amortized to income tax expense over the life of the intellectual property. Effective January 1, 2018, pursuant to the Company’s modified retrospective adoption of ASU 2016-16, the Company’s remaining prepaid tax asset of $3,216 was recorded as an increase to accumulated deficit.

In December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”). The Tax Act significantly impacts the future ongoing U.S. corporate income tax by, among things, lowering the U.S. corporate income tax rates from 34% to 21%, providing for unlimited net operating loss carry-forward periods, and implementing a territorial tax system. The reduction of the U.S. corporate tax rate required the Company to revalue its U.S. deferred tax assets and liabilities during fiscal 2017 to the newly enacted federal rate of 21%. This transitional impact resulted in a provisional deferred tax benefit of $2,024 in the yearyears ended December 31, ~~2017 related to a reduction in a US deferred tax liability on certain long-~~

lived acquired intangibles. This transitional impact also resulted in a $87,621 provisional reduction of certain of the Company’s US deferred tax assets which are offset by a full valuation allowance.

As of December 31, 2019, the amounts recorded for the Tax Act no longer remain provisional as the Company completed its accounting for the effect of the 2017 Tax Act within the measurement period under the SEC guidance. However, the amounts recorded for the repatriation tax, the remeasurement of deferred taxes, and the Company’s reassessment of permanently reinvested earnings, uncertain tax positions and valuation allowances may be impacted by future clarification and guidance regarding available tax accounting methods and elections, earnings and profits computations, state tax conformity to federal tax changes, among others.

~~During the year ended~~ December 31, 2019, the Company recorded a current and deferred tax expense of $27,106 and $17,670, respectively, related to the transfer of certain intellectual property rights from its wholly owned ~~subsidiary~~subsidiaries in Israel. During the year ended December 31, 2018, the Company recorded a deferred tax benefit of $14,725 related to changes in the Company’s valuation allowance resulting from the Wombat business acquisition. During the year ended December 31, 2017, the Company recorded a deferred tax benefit of $7,904 and $4,440 related to changes in the Company’s US valuation allowances as a result of the Cloudmark and WebLife acquisitions, respectively.

As of December 31, ~~2019~~2020 and ~~2018,~~2019, the Company had net operating loss carry-forwards for federal income tax purposes of ~~$841,970~~$887,601 and ~~$797,569,~~$841,970, respectively. The federal net operating losses generated prior to tax year beginning in 2018 and which are subject to expiration will expire between ~~2020~~2021 and 2037. As of December 31, ~~2019~~2020 and ~~2018,~~2019, the Company had federal research credit carry-forwards of ~~$37,783~~$48,867 and ~~$24,556~~$37,783 respectively. The federal research and development credits will begin to expire in 2022.

As of December 31, ~~2019~~2020 and ~~2018,~~2019, the Company had net operating loss carry-forwards for state income tax purposes of approximately ~~$417,505~~$431,531 and ~~$396,665,~~$417,505, respectively. The state net operating losses will continue to expire between ~~2019~~2021 and 2039. As of December 31, ~~2019~~2020 and ~~2018,~~2019, the Company had research and development credit carry-forwards for state income tax purpose of ~~$32,291~~$37,879 and ~~$22,987,~~$32,291, respectively. The state research and development credits have no expiration period.

As of December 31, 2020, the Company had 0 net operating losses carry-forwards in non-U.S. locations. As of December 31, 2019, the Company had net operating losses carry-forwards in non-U.S. locations of approximately $52,851. As of December 31, ~~2018, the Company had 0 net operating losses carry-forwards in non-U.S. locations. As of December 31,~~2020 and 2019, ~~and 2018,~~ the Company had research and development credit carry-forwards in its non-U.S. locations of approximately ~~$2,863~~$3,119 and ~~$2,426,~~$2,863, respectively. The non-U.S. research and development credits will begin to expire in 2032.

Utilization of the federal and state net operating losses may be subject to substantial annual limitation due to the ownership change limitations provided by the Internal Revenue Code and similar state provisions. Analyses have been conducted to determine whether an ownership change had occurred since inception. The analyses have indicated that although ownership changes have occurred in prior years, the net operating losses and research and development credits would not expire before utilization as a result of the ownership change. In the event the Company has subsequent changes in ownership, net operating losses and research and development credit carryovers could be limited and may expire unutilized as a result of the subsequent ownership change.

The Company recognizes interest and penalties related to uncertain tax positions within the income tax expense line in the consolidated statements of operations. Accrued interest and penalties are included within the related tax liability line in the consolidated balance sheets. During the year ended December 31, 2020, the Company increased income tax expense by $1,303 from interest and penalties related to tax contingencies and has $1,981 of interest and penalties recorded as a long-term income tax liability. December 31, 2019, the Company increased income tax expense by $368 from interest and penalties related to tax contingencies and has $677 of interest and penalties recorded as a long-term income tax liability. During the year ended December 31, 2018, the Company reduced income tax benefit by $21 from interest and penalties related to tax contingencies and has $309 of interest and penalties recorded as a long-term income tax liability as of December 31, 2018.

As of December 31, 2020, the Company had recorded unrecognized tax benefits of $35,066 that if recognized, would benefit the Company’s effective tax rate. As of December 31, 2019, the Company had recorded unrecognized tax benefits of $16,068 that, if recognized, would benefit the Company’s effective tax rate. ~~As of December 31, 2018, the Company had recorded unrecognized tax benefits of $4,616 that, if recognized, would benefit the Company’s effective tax rate.~~

The Company is currently under audit by the Israel Tax Authority for tax years ~~2013~~2016 through ~~2017.~~2018. Related to the audit by the Israel Tax Authority it is reasonably possible that the Company’s uncertain tax positions could change within the next 12 months. An estimate of the range of any change cannot be made. The Company believes it has recorded all appropriate provisions for all jurisdictions and open years. However, the Company can give no assurance that taxing authorities will not propose adjustments that would increase its tax liabilities. The Company is not currently under audit by the IRS or any similar taxing authority in any other material jurisdiction.

Because of net operating loss and credit carry-forwards, all of the Company’s tax years dating to inception in 2002 remain open to tax examination in U.S. and certain state tax jurisdictions. For other major non-U.S. jurisdictions, tax years from 2012 to present remain open to tax examination. The Company is not currently under audit in any material jurisdictions.

The aggregate changes in the balance of gross unrecognized tax benefits were as follows:

Balance as of December 31, 2016	$	5,846
Increase in balances related to tax positions taken during the current period		8,160
Increase in balances related to tax positions taken during the prior period		45
Decrease in balances related to tax positions taken during the prior period		(2	)
Decrease in balances related to statute expirations during the current period		(188	)
Balance as of December 31, 2017		13,861		$	13,861
Increase in balances related to tax positions taken during the current period		2,692			2,692
Increase in balances related to tax positions taken during the prior period		217			217
Decrease in balances related to tax positions taken during the prior period		—			—
Decrease in balances related to statute expirations during the current period		(316	)		(316	)
Balance as of December 31, 2018		16,454			16,454
Increase in balances related to tax positions taken during the current period		14,195			14,195
Increase in balances related to tax positions taken during the prior period		2,637			2,637
Decrease in balances related to tax positions taken during the prior period		—			—
Decrease in balances related to statute expirations during the current period		(116	)		(116	)
Balance as of December 31, 2019	$	33,170			33,170
Increase in balances related to tax positions taken during the current period					20,658
Increase in balances related to tax positions taken during the prior period					1,399
Decrease in balances related to tax positions taken during the prior period					—
Decrease in balances related to statute expirations during the current period					(194	)
Balance as of December 31, 2020				$	55,033

As part of the transition to the new territorial tax system, the Tax Act imposed a one-time repatriation tax on deemed repatriation of historical earnings of foreign subsidiaries. Based on the evaluation of the Company’s operations, 0 repatriation tax charge was owed due to negative earnings and profits in the Company’s foreign operations.

Incorporated by Reference

Exhibit

No.

Exhibit Title

Form

File No.

Filing Date

Exhibit

No.

Exhibit Title

Form

File No.

Filing Date

Exhibit No.

2.1

Share Purchase Agreement among Proofpoint Israel Holdings Limited, ObserveIT Ltd. and Shareholder Representative Services, LLC, dated November 2, 2019.

3.01

Amended and Restated Certificate of Incorporation of the Registrant.

S-1A

333-178479

April 9, 2012

3.02

Amended and Restated Certificate of Incorporation of the Registrant.

S-1A

333-178479

April 9, 2012

3.02

Amended and Restated Bylaws of the Registrant.

8-K

001-35506

February 20, 2019

3.1

Amended and Restated Bylaws of the Registrant.

8-K

001-35506

February 20, 2019

3.1

4.01

Form of Registrant’s common stock certificate.

S-1A

333-178479

April 9, 2012

4.01

Form of Registrant’s common stock certificate.

S-1A

333-178479

April 9, 2012

4.01

4.02

Indenture between Registrant and Wells Fargo Bank, National Association (including the form of 0.25% Convertible Senior Notes due 2024), dated August 23, 2019.

8-K

001-35506

August 23, 219

4.1

Indenture between Registrant and Wells Fargo Bank, National Association (including the form of 0.25% Convertible Senior Notes due 2024), dated August 23, 2019.

8-K

001-35506

August 23, 219

4.1

4.03

Description of Securities Registered Under Section 12 of the Exchange Act.

10.01

Form of Indemnity Agreement.

10-Q

001-35506

October 31, 2017

10.01

Form of Indemnity Agreement.

10-Q

001-35506

October 31, 2017

10.01

10.02

†

2002 Stock Option/Stock Issuance Plan and form of option grant.

S-1A

333-178479

April 9, 2012

10.02

†

2002 Stock Option/Stock Issuance Plan and form of option grant.

S-1A

333-178479

April 9, 2012

10.02

10.03

†

Amended and Restated 2012 Equity Incentive Plan and Form of Grant Agreements

10-Q

001-35506

July 29, 2019

10.01

†

Amended and Restated 2012 Equity Incentive Plan and Form of Grant Agreements

10-Q

001-35506

July 29, 2019

10.01

10.04

†

2012 Employee Stock Purchase Plan.

S-1A

333-178479

April 9, 2012

10.04

†

2012 Employee Stock Purchase Plan.

S-1A

333-178479

April 9, 2012

10.04

10.05

†

Corporate Bonus Program.

10-K

001-35506

February 26, 2015

10.05

†

Corporate Bonus Program.

10-K

001-35506

February 26, 2015

10.05

10.06

Lease between the Registrant and Pathline LLC, dated October 23, 2018

8-K

001-35506

October 25, 2018

10.1

Lease between the Registrant and Pathline LLC, dated October 23, 2018

8-K

001-35506

October 25, 2018

10.1

10.07

†

Offer Letter to Gary Steele from the Registrant, dated November 17, 2002.

S-1

333-178479

December 14, 2011

10.07

†

Offer Letter to Gary Steele from the Registrant, dated November 17, 2002.

S-1

333-178479

December 14, 2011

10.07

10.08

†

Offer Letter to Paul Auvil from the Registrant, dated March 9, 2007.

S-1A

333-178479

January 25, 2012

10.08

†

Offer Letter to Paul Auvil from the Registrant, dated March 9, 2007.

S-1A

333-178479

January 25, 2012

10.08

10.09

†

Offer Letter to David Knight from the Registrant, dated March 14, 2011.

S-1A

333-178479

January 25, 2012

10.11

†

Offer Letter to David Knight from the Registrant, dated March 14, 2011.

S-1A

333-178479

January 25, 2012

10.11

10.10

†

Offer Letter to Blake Salle from the Registrant, dated October 24, 2018.

10-K

001-35506

February 21, 2019

10.11

†

Offer Letter to Blake Salle from the Registrant, dated October 24, 2018.

10-K

001-35506

February 21, 2019

10.11

†

Offer Letter to Bhagwat Swaroop from Registrant, dated April 27, 2016.

10-K

001-35506

February 23, 2017

10.12

†*

Offer Letter to Ashan Willy from the Registrant, dated October 16 2016.

21.01

Subsidiaries of Registrant.

23.01

Consent of PricewaterhouseCoopers LLP, independent registered public accounting firm.

31.01

Certification of Chief Executive Officer Pursuant to Rule 13-a-14 of the Securities Exchange Act of 1934, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

31.02

Certification of Chief Financial Officer Pursuant to Rule 13-a-14 of the Securities Exchange Act of 1934, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

32.01

Certification of Chief Executive Officer Pursuant to 18 U.S.C. Section 1350 as Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

32.02

Certification of Chief Financial Officer Pursuant to 18 U.S.C. Section 1350 as Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

101.INS

Inline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

Inline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCH

Inline XBRL Taxonomy Extension Schema Document.

101.CAL

Inline XBRL Taxonomy Extension Calculation Linkbase Document.

101.DEF

Inline XBRL Taxonomy Extension Definition Linkbase Document.

101.LAB

Inline XBRL Taxonomy Extension Label Linkbase Document.

101.PRE

Inline XBRL Taxonomy Extension Presentation Linkbase Document.

104

Cover Page Interactive Data File (formatted as inline XBRL and contained in Exhibit 101.

₊ Schedules have been omitted pursuant to Item 601(b)(2) of Regulation S-K. The Registrant agrees to furnish supplementally to the SEC a copy of any omitted schedule upon request.

**These exhibits are furnished with this Annual Report on Form 10-K and are not deemed filed with the Securities and Exchange Commission and are not incorporated by reference in any filing of Proofpoint, Inc. under the Securities Act of 1933 or the Exchange Act of 1934, whether made before or after the date hereof and irrespective of any general incorporation language in such filings.

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Company has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized, on February ~~20, 2020.~~19, 2021.

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Gary Steele and Paul Auvil, and each of them, as his or her true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for him or her and in his or her name, place and stead, in any and all capacities, to sign any and all amendments to this Annual Report on Form 10-K, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming that all said attorneys-in-fact and agents, or any of them or their or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons in the capacities and on the date indicated:

Delaware		51-0414846
(State or other jurisdiction of incorporation or organization)		(I.R.S. employer identification no.)

~~892 Ross Drive~~925 West Maude Avenue Sunnyvale, California		~~94089~~94085
(Address of principal executive offices)		(Zip Code)

Title of Each Class		Trading Symbol(s)	Name of each exchange on which registered
Common Stock, $0.0001 par value per share		PFPT	~~NASDAQ~~The Nasdaq Global Select Market

		Page
PART I.

Item 1.	Business	4

Item 1A.	Risk Factors	1417

Item 1B.	Unresolved Staff Comments	3135

Item 2.	Properties	3135

Item 3.	Legal Proceedings	3135

Item 4.	Mine Safety Disclosures	3135

PART II.

Item 5.	Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities	3236

Item 6.	Selected Financial Data	3338

Item 7.	Management's Discussion and Analysis of Financial Condition and Results of Operations	3540

Item 7A.	Quantitative and Qualitative Disclosures About Market Risk	5359

Item 8.	Financial Statements and Supplementary Data	5359

Item 9.	Changes in and Disagreements with Accountants on Accounting and Financial Disclosure	5360

Item 9A.	Controls and Procedures	5360

Item 9B.	Other Information	5460

PART III.

Item 10.	Directors, Executive Officers and Corporate Governance	5561

Item 11.	Executive Compensation	5561

Item 12.	Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters	5561

Item 13.	Certain Relationships and Related Transactions, and Director Independence	5561

Item 14.	Principal Accountant Fees and Services	5561

PART IV.

Item 15.	Exhibits and Financial Statement Schedules	5662

Signatures		~~100~~102

Period	Total Number of Shares Repurchased		Average Price Paid Per Share		Number of Shares Purchased as Party of Publicly Announced Program		Maximum Number (or Approximate Dollar Value) of Shares That May Yet Be Purchased Under the Program

	(in thousands, except per share amounts)
October 1, 2020 - October 31, 2020		471	$	107.58		471	$	237,613
November 1, 2020 - November 30, 2020		506	$	98.83		506	$	187,575
December 1, 2020 - December 31, 2020		246	$	109.69		246	$	160,644
Total		1,223	$	104.38		1,223

	December 31, 2014		December 31, 2015		December 31, 2016		December 31, 2017		December 31, 2018		December 31, 2019
Proofpoint, Inc.	$	100.00	$	134.79	$	146.49	$	184.14	$	173.77	$	237.98
NASDAQ Composite - Total Returns	$	100.00	$	106.96	$	116.45	$	150.96	$	146.67	$	200.49
NASDAQ Computer Index	$	100.00	$	106.24	$	119.28	$	165.52	$	159.43	$	239.67

Large accelerated filer	☑	Accelerated filer	☐
Non-accelerated filer	☐	Smaller reporting company	☐
		Emerging growth company	☐


	Page
Report of Independent Registered Public Accounting Firm	5763

Consolidated Balance Sheets	6065

Consolidated Statements of Operations	6166

Consolidated Statements of Comprehensive Loss	6267

Consolidated Statements of Stockholders' Equity	6368

Consolidated Statements of Cash Flows	6469

Notes to Consolidated Financial Statements	6671

	Low		High
Developed technology		2		7
Customer relationships		2		8
Trade names and trademarks		1		5
Patents		4		5
Order backlog		1		3

	Useful Life		December 31,
	(in years)		2019			2018
Computer equipment	2 to 4		$	170,010		$	142,777
Software	2 to 5			5,184			3,782
Furniture		5		4,244			3,637
Office equipment	2 to 5			658			585
Leasehold improvements	5 years, or lease term, if shorter			14,819			13,129
Other		2		408			59
Construction in progress				3,630			1,088
				198,953			165,057
Less: Accumulated depreciation				(125,441	)		(94,430	)
			$	73,512		$	70,627

	December 31, 2020
	Total		Level 1		Level 2		Level 3
Assets
Cash equivalents:
Money market funds	$	865,924	$	865,924	$	—	$	—
Total financial assets	$	865,924	$	865,924	$	—	$	—

	Ending Balance as of December 31, 2018			Adjustments			Opening Balance as of January 1, 2019
Assets
Prepaid expenses and other current assets	$	16,872		$	(81	)	$	16,791
Operating lease right-of-use assets	$	—		$	59,549		$	59,549
Liabilities
Accounts payable	$	20,237		$	(216	)	$	20,021
Deferred rent	$	829		$	(829	)	$	—
Operating lease liabilities	$	—		$	24,820		$	24,820
Long-term operating lease liabilities	$	—		$	39,361		$	39,361
Long-term deferred rent	$	3,757		$	(3,757	)	$	—
Stockholders’ Equity
Accumulated deficit	$	(595,418	)	$	89		$	(595,329	)

	Operating leases
Year ending December 31,
2021	$	26,352
2022		37,331
2023		27,053
2024		23,664
2025		23,247
Thereafter		122,741
Total lease payments		260,388
Less imputed interest		(53,322	)
Total	$	207,066

	Year Ended December 31,
	2019
Operating lease cost	$	26,115
Short-term lease cost		2,846
Variable lease cost		3,444
Total lease cost	$	32,405

	Year Ended December 31,
	2019

Cash paid for amounts included in the measurement of operating lease liabilities	$	27,104
Right-of-use assets obtained in exchange for operating lease obligations	$	15,668
Weighted-average remaining lease term - operating leases	4 years
Weighted-average discount rate - operating leases		5.04	%

Liability as of December 31, 2018	Operating Leases
2019	$	25,313
2020		17,535
2021		19,155
2022		21,581
2023		19,609
Thereafter		129,154
Total minimum lease payments	$	232,347

	PROOFPOINT, INC.

	By:		/s/ GARY STEELE
			Gary Steele Chief Executive Officer

Name	Title		Date

/s/ Gary Steele	Chief Executive Officer (Principal Executive Officer)		February ~~20, 2020~~19, 2021
Gary Steele	Chief Executive Officer (Principal Executive Officer)

/s/ Paul Auvil	Chief Financial Officer (Principal Financial Officer and Principal Accounting officer)		February ~~20, 2020~~19, 2021
Paul Auvil

/s/ Dana Evan	Director		February ~~20, 2020~~19, 2021
Dana Evan	Director

/s/ Jonathan Feiber	Director		February ~~20, 2020~~19, 2021
Jonathan Feiber	Director

/s/ Kristen Gil	Director		February ~~20, 2020~~19, 2021
Kristen Gil	Director

/s/ Kevin Harvey	Director		February ~~20, 2020~~19, 2021
Kevin Harvey	Director

~~/s/ R. Scott Herren~~	~~Director~~		~~February 20, 2020~~
~~R. Scott Herren~~	~~Director~~

/s/ Michael Johnson	Director		February ~~20, 2020~~19, 2021
Michael Johnson	Director

/s/ Leyla Seka	Director	February ~~20, 2020~~19, 2021
Leyla Seka

/s/ Richard Wallace	Director		February ~~20, 2020~~19, 2021
Richard Wallace	Director