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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of

the Securities Exchange Act of 1934 (Amendment No.        )

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PTC Therapeutics, Inc.

100 Corporate Court

South Plainfield, New Jersey 07080

April 29, 202128, 2022

Dear Stockholder:

You are cordially invited to attend the 20212022 Annual Meeting of Stockholders of PTC Therapeutics, Inc., on Tuesday,Wednesday, June 8, 20212022 at 9:00 a.m., Eastern Time. Due to the continuing public health impact of the ongoing COVID-19 pandemic and governmental restrictions limiting the number of people who may gather together, and to support the health and well-being of our stockholders, directors, employees and communities, the Annual Meeting will be held over the Internet in a virtual meeting format, via live webcast at www.virtualshareholdermeeting.com/PTCT2021.PTCT2022. There will not be a physical meeting location for the Annual Meeting and stockholders will not be able to attend the Annual Meeting in person.

The attached Notice of the Annual Meeting and proxy statement provide important information about the Annual Meeting and will serve as your guide to the business to be conducted at the meeting. Your vote is very important to us. We urge you to read the accompanying materials regarding the matters to be voted on at the Annual Meeting and to submit your voting instructions by proxy. Our Board of Directors recommends that you vote "for" each of the proposals listed on the attached Notice.

You may submit your proxy by Internet, by telephone or by requesting, prior to May 25, 2021,2022, a printed or emailed copy of the proxy materials and using the enclosed proxy card. If you submit your proxy before the meetingAnnual Meeting but later decide to virtually attend the Annual Meeting, you may still vote at the Annual Meeting.

On behalf of our Board of Directors, management and all of our employees, I thank you for your continuing support and confidence.

As always, we encourage you to vote your shares prior to the Annual Meeting regardless of whether you intend to attend.

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PTC Therapeutics, Inc.

100 Corporate Court

South Plainfield, New Jersey 07080

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NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To be held on June 8, 20212022

To the Stockholders of PTC Therapeutics, Inc.:

This proxy statement contains information about the 20212022 Annual Meeting of Stockholders of PTC Therapeutics, Inc., which we refer to as the Annual Meeting. Due to the continuing public health impact of the ongoing COVID-19 pandemic and governmental restrictions limiting the number of people who may gather together, and to support the health and well-being of our stockholders, directors, employees and communities, the Annual Meeting will be held on Tuesday,Wednesday, June 8, 20212022 at 9:00 a.m., Eastern Time, over the Internet in a virtual format, via live webcast at www.virtualshareholdermeeting.com/PTCT2021.PTCT2022. There will not be a physical meeting location for the Annual Meeting, and stockholders will not be able to attend the Annual Meeting in person.

At the Annual Meeting, stockholders will consider and act upon the following matters:

Instead of mailing a printed copy of our proxy materials to all of our stockholders, we provide access to these materials via the Internet. This reduces the amount of paper necessary to produce these materials as well as the costs associated with mailing these materials to all stockholders. Accordingly, on or about April 29, 2021,28, 2022, we will begin mailing a Notice of Internet Availability of Proxy Materials, or Notice, to stockholders of record at the close of business on April 16, 2021,14, 2022, the record date for the Annual Meeting, and will post our proxy materials on the website referenced in the Notice. As more fully described in the Notice, stockholders may choose to access our proxy materials on the website referred to in the Notice or may request, prior to May 25, 2021,2022, to receive a printed or emailed set of our proxy materials.

We encourage you to vote in one of the following ways:

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If your shares are held in “street name,” meaning that they are held for your account by a broker or other nominee, you may receive additional instructions from your broker or other nominee on how to vote your shares.

Whether or not you plan to virtually attend the Annual Meeting, we urge you to take the time to vote your shares.

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PTC Therapeutics, Inc.

100 Corporate Court

South Plainfield, New Jersey 07080

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PROXY STATEMENT FOR THE ANNUAL MEETING OF STOCKHOLDERS

To be held on June 8, 20212022

These proxy materials are being furnished in connection with the solicitation of proxies by our Board of Directors for use at the 20212022 Annual Meeting to be held on Tuesday,Wednesday, June 8, 20212022 at 9:00 a.m., Eastern Time, via live webcast at www.virtualshareholdermeeting.com/PTCT2021,PTCT2022, or the Annual Meeting Website, and at any adjournment or postponement thereof. Due to the continuing public health impact of the ongoing COVID-19 pandemic and governmental restrictions limiting the number of people who may gather together, and to support the health and well-being of our stockholders, directors, employees and communities, the Annual Meeting will be conducted over the Internet in a virtual format. There will not be a physical meeting location for the Annual Meeting, and stockholders will not be able to attend the Annual Meeting in person.

All proxies will be voted in accordance with the instructions contained in those proxies. If no choice is specified, the proxies will be voted "for" each of the director nominees and "for" each of the proposals set forth in the accompanying Notice of Annual Meeting of Stockholders. You may revoke your proxy at any time before it is exercised at the meetingAnnual Meeting by giving our Secretary written notice to that effect.

The Notice of Annual Meeting and proxy statement are first being mailed and/or made available to stockholders on or about April 29, 202128, 2022 in conjunction with the delivery of our 20202021 Annual Report to Stockholders.

In this proxy statement, unless expressly stated otherwise or the context otherwise requires, the use of "PTC," "the Company," "our," "we" or "us" refers to PTC Therapeutics, Inc., and its subsidiaries. Certain information contained in this proxy statement relating to the occupations and security holdings of our directors and officers is based upon information received from the individual directors and officers.

Whether or not you expect to virtually attend the Annual Meeting, please vote as promptly as possible to ensure your representation and the presence of a quorum at the Annual Meeting. You may vote your shares on the Internet by visiting www.proxyvote.com or by telephone by calling 1-800-690-6903 and following the recorded instructions, by requesting, prior to May 25, 2021,2022, a printed or emailed copy of the proxy materials and using the enclosed proxy card or by voting via the Annual Meeting Website at the Annual Meeting. Your proxy is revocable in accordance with the procedures set forth in this proxy statement.

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All website addresses given in this proxy statement are for information only and are not intended to be an active link or to incorporate any website information into this document.

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IMPORTANT INFORMATION ABOUT THE ANNUAL MEETING AND VOTING

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PROPOSAL 1: ELECTION OF DIRECTORS

Information Regarding Directors and Director Nominees

Board Composition

We currently have a classified board of directors consisting of three classes: Class I, Class II, and Class III. The terms of service of the three classes are staggered so that the term of one class expires each year. At each annual meeting of stockholders, directors are elected for a full term of three years to continue in office or to succeed those directors whose terms are expiring. Our directors hold office until their successors have been elected and qualified, or until the earlier of their resignation or removal.

Our certificate of incorporation and bylaws provide that the authorized number of directors may be changed only by resolution of our Board; that our directors may be removed only for cause by the affirmative vote of the holders of at least 75% of the votes entitled to be cast in an annual election of directors; and that any vacancy on our Board, including a vacancy resulting from an enlargement of our Board, may be filled only by vote of a majority of our directors then in office.office or at a meeting of stockholders. Our Board is authorized to have teneleven directors and currently consists of nineten directors, three Class I directors, threefour Class II directors, and three Class III directors with one vacancy, which the Board intends to fill at the Annual Meeting.

There are no family relationships between or among any of our executive officers, directors or director nominees. The principal occupation and employment during the past five years of each of our directors and director nominees was carried on, in each case except as specifically identified below, with a corporation or organization that is not a parent, subsidiary or other affiliate of us. There is no arrangement or understanding between any of our directors or director nominees and any other person or persons pursuant to which he was or is to be selected as a director or director nominee.

Director Nominees

At the Annual Meeting, stockholders will be asked to consider the election of Emma Reeve, Michael Schmertzler, Glenn D. Steele Jr.Allan Jacobson, Ph.D., M.D., Ph.D.David P. Southwell, Dawn Svoronos and Mary Smith.Alethia Young. Upon the recommendation of our Nominating and Corporate Governance Committee, our Board has nominated Dr. Jacobson, Mr. Southwell, Ms. Reeve, Mr. Schmertzler, Dr. SteeleSvoronos and Ms. SmithYoung for election at the Annual Meeting as Class IIIII directors, each to serve until 2024.2025.

Each of Dr. Jacobson, Mr. Southwell, Ms. Reeve, Mr. Schmertzler, Dr. SteeleSvoronos and Ms. Smith,Young, our director nominees, has indicated his or her willingness to serve on our Board, if elected. If any director nominee should be unable to serve, the person acting under the proxy may vote the proxy for a substitute director nominee designated by our Board. We do not contemplate that any of our director nominees will be unable to serve if elected.

Unless otherwise instructed in the proxy, all proxies will be voted "FOR" the election of each of the director nominees identified above to a three-year term ending in 2024,2025, each such director nominee to hold office until his or her successor has been duly elected and qualified.

A plurality of the voting power of the shares of common stock present in person or represented by proxy at the Annual Meeting and entitled to vote is required to elect each director nominee as a director. Proxies cannot be voted for a greater number of persons than the number of nominees named.

Our Board Recommends that You Vote "FOR" the Election of Emma Reeve, Michael Schmertzler, Glenn D. Steele Jr., M.D., Ph.D.Allan Jacobson, David P. Southwell, Dawn Svoronos and Mary SmithAlethia Young.

Biographical Information

The following table and biographical descriptions provide information as of April 16, 202114, 2022 relating to each director nominee and each director continuing in office, including age and period of service as a director of our Company; committee memberships; business experience during the past five years, including directorships at other public

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companies; community activities; and the other experience, qualifications, attributes or skills that led our Board to conclude that such director should serve as a director of PTC.

Class IIIII Director nominees to be elected at the Annual Meeting (current terms expiring in 2021)2022)

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Class I Directors (terms expiring in 2023)

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Class I Directors (terms expiring in 2024)

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PROPOSAL 2: AMENDMENTVOTE TO APPROVE THE COMPANY’S AMENDED AND RESTATED CERTIFICATE OF 2013 LONG-TERM INCENTIVE PLAN

INCORPORATION TO INCREASE THE NUMBER OF AUTHORIZED SHARES OF COMMON STOCK FROM 125,000,000 TO 250,000,000General

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On March 23, 2021,We are asking stockholders to approve an amendment and restatement of our 2013 Long-Term Incentive Plan. In this proposal, we refer to the currently existing version of the 2013 Long-Term Incentive Plan as the Plan, and we refer to the amended and restated version of the 2013 Long-Term Incentive Plan as the Restated Plan. We have maintained the Plan since our initial public offering in 2013. We believe that our success and continued growth depends, in large part, on our ability to maintain a competitive position by attracting, retaining and motivating key employees with experience and ability. As further described under the heading “Reasons Why Stockholders Should Approve the Restated Plan”, we believe that our stock-based compensation programs are central to this objective while also aligning our employee’s interests with that of our stockholders in a manner that promotes sound corporate governance. The Plan expires, in accordance with its terms, in June 2023. Therefore, on April 11, 2022, our Board, upon the recommendation of our Nominating and Corporate GovernanceCompensation Committee, our Board approved the adoption, of and declared advisable to the Company and its stockholders, subject to stockholder approval, an amendmentof the Restated Plan.

The Restated Plan includes the following material changes to the Company’s Restated CertificatePlan:

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If our stockholders approve the Restated Certificate,Plan, including the increase to increasethe share reserve, then, subject to adjustment in the event of stock splits and other similar events, the maximum number of shares authorized for issuance under the Restated Plan will be equal to (1) the number of authorized shares of common stock, par value $0.001 per share, from 125,000,000 shares to 250,000,000 shares. The proposed amendment to the Restated Certificate would not increase or otherwise affect our authorized preferred stock.

Our Board believes it is in the best interest of the Company and its stockholders to increase the number of authorized shares of common stock to give the Company greater flexibility in considering and planning for future potential business needs and pursuing our strategic goals. We currently have no specific plans, arrangements or understandings to issue additional shares of our common stock except(up to 16,724,212 shares) that is equal to the sum of (x) the number of shares issued under the Plan prior to approval of the Restated Plan, (y) the number of shares that remain available for issuance under the Plan immediately prior to approval of the Restated Plan and (z) the number of shares subject to awards granted under the Plan prior to approval of the Restated Plan that are outstanding as of the date of approval of the Restated Plan, plus (2) from and after the date on which the Restated Plan is approved, an additional 8,475,000 shares, which shall be available for the issuancegrant of future awards.

As of April 14, 2022, options to purchase an aggregate of 11,812,951 shares of common stock pursuant to our equity incentive plans to persons eligible to participate in those plans, including pursuant towere outstanding under the proposed amendment to our 2016 EmployeePlan, the 2009 Equity and Long-Term Incentive Plan, as amended, or the 2009 Plan, the 2013 Stock PurchaseIncentive Plan, or the 2013 SIP, or as inducement option awards, having a weighted-average remaining term of 6.94 years and potential future issuances pursuant to our at-the-market sales agreement with Cantor Fitzgerald & Co. and RBC Capital Markets, LLC, dated August 7, 2019, or our at-the-market sales agreement. However, the availabilitya weighted-average exercise price of additional$43.10 per share, 2,542,803 shares of common stock for issuance is, inwere subject to outstanding restricted stock units granted under the Board's view, prudentPlan or as inducement awards, and will afford5,285 shares of restricted stock were outstanding under the company with flexibility in acting upon financing transactions to strengthen our financial position and/or commercial partnership opportunities that may arise. The increase in the number of authorized but unissuedPlan, and an additional 922,694 shares of common stock would enable our Board, withoutwere reserved for future awards under the expensePlan and delay of seeking stockholder approval, to issue shares from time to time as may be required for proper business purposes. The additional shares of common stock will be available for issuance by our Board for various corporate purposes, including but not limited to, grants under our equity incentive award plans, financings such as public or private offerings of common stock or convertible securities, including issuances under our at-the-market sales agreement, satisfaction of potential milestone payment obligations, potential settlement of conversions of our 3.00% convertible senior notes due August 15, 2022 and our 1.50% convertible senior notes due September 15, 2026, potential strategic transactions, including mergers, acquisitions, strategic partnerships, collaborations, strategic investments, joint ventures, divestitures, business combinations, stock splits, stock dividends as well as other general corporate transactions and other corporate purposes that have not yet been identified. If the authorization of an increase in the available common stock is postponed until the foregoing specific needs arise, the delay and expense incident to obtaining approval of the stockholders at that time could impair our ability to achieve the corporate purposes set forth above.

The Restated Certificate currently authorizes the issuance of up to 125,000,000 shares of common stock, par value $0.001 per share, and 5,000,000 shares of preferred stock, par value $0.001 per share. As of April 16, 2021, 70,418,067 shares of our common stock were outstanding and our Board had reserved 12,623,895 shares of common stock for issuance upon the exercise of outstanding stock options and unvested restricted stock units, 752,366 shares of common stock for issuance pursuant to our 2013 Long Term Incentive Plan, 1,096,710 shares of common stock for issuance pursuant to our 2020 Inducement Stock Incentive Plan.

Awards granted under the 2009 Plan as amended, and 359,167the 2013 SIP prior to our initial public offering remain outstanding under the applicable plan. Any shares of common stock subject to awards under these plans that expire, terminate or are otherwise surrendered, canceled, forfeited or without having been fully exercised or resulting in any common stock being issued will be available for issuance pursuantgrant under the Plan up to a specified number of shares as set forth in the Plan.

Assuming that aggregate equity awards are granted at levels consistent with recent historical practices, then we generally expect that the share reserve under the Restated Plan should be sufficient to cover our projected stock grants for a period of approximately three years, but the actual timeline may vary based on changes in participation, market practices and our stock price. If the Restated Plan is not approved, we expect to be able to make awards under the Plan for the remainder of the term of the Plan.

Reasons Why Stockholders Should Approve the Restated Plan

Attracts, Retains and Motivates Talent. It is critical to our 2016 Employee Stock Purchase Plan. In addition,success that we recruit, retain and motivate the best talent in what is a tremendously competitive labor market. Equity-based compensation has always been and will continue to be a key component in our Board has reserved upability to 10,577,310 shares of common stock for issuance upon conversionpay market-competitive compensation to our newly hired employees, but also to preserve our existing employees. Indeed, historically, we have provided equity awards to all of our 3.00% convertible senior notes due August 15, 2022employees upon commencement of employment and annually in our 1.50% convertible senior notes due September 15, 2026. Ascontinuing effort to foster a result, the Company has only 29,172,485 sharesculture in which every employee is responsible for our successes and is rewarded for our achievements. We believe that our employees and potential employees expect equity awards to be a key ongoing part of common stock available for future issuance out of the 125,000,000 shares of common stock currently authorized as of March 31, 2021. Additionally, we have the option to pay our contingent obligations of (i) up to $200.0 million in potential milestone payments to BioElectron pursuant to an Asset Purchase Agreement by and between us and BioElectron, dated October 1, 2019 and (ii) a $30.0 million development milestone payment upon the completion of enrollment of a Phase 3 clinical trial for PTC923 for PKU to former Censa securityholders pursuant to an Agreement and Plan of Merger, dated as of May 5, 2020, by and among us, Hydro Merger Sub, Inc., our wholly owned, indirect subsidiary, and, solely in its capacity as the representative, agent and attorney-in-fact of the securityholders of Censa, Shareholder Representatives Services LLC, in sharestheir compensation. In fact, approximately 81% of our common stock ratheremployee annual equity awards in 2021 were granted to employees other than in cash. Our Board has also approved, and we are seeking stockholder approval of, an increase of 1,000,000 shares of common stock to be reserved for issuance under the 2016 Employee Stock Purchase Plan, as described in Proposal 3.our named executive officers based upon

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If this proposal is approved, the additional authorized shares may be issued at the discretiongrant date fair market value of our Board without further stockholder action, except as may be required by law or the rules of Nasdaq. The adoption of the proposed amendment to the Restated Certificate would not have any immediate dilutive effect on the proportionate voting power or other rights of existing stockholders. However, the issuance of shares of common stock, other than on a pro-rata basis to all stockholders, would reduce each stockholder’s proportionate interest in the Company and the issuance of additional shares of common stock may, among other things, have a dilutive effect on earnings per share and on stockholders'annual equity and voting rights. Furthermore, future sales of substantial amounts of our common stock, or the perception that these sales might occur, could adversely affect the prevailing market price of our common stock or limit our ability to raise additional capital. Stockholders should recognize that, as a result of this proposal, they will own a smaller percentage of shares relative to the total authorized shares of the company than they presently own. The holders of any of the additional shares of common stock issued in the future would have the same rights and privileges as the holders of the shares of common stock currently authorized and outstanding. Those rights do not include preemptive rights with respect to the future issuance of any additional shares. The holders of shares of our common stock will have no dissenters' rights of appraisal under Delaware law, our Restated Certificate or our Bylaws with respect to the proposed amendment to the Restated Certificate.

The issuance of additional shares of common stock could have the effect of making it more difficult for a third party to acquire, or discouraging a third party from attempting to acquire, control of the company. We are not aware of any attempts on the part of a third party to effect a takeover of the company, and the proposed amendment to the Restated Certificate has been proposed for the reasons stated above and not with the intention that any increase in the authorized shares of common stock be used as a type of anti-takeover device.

A copy of the proposed amendment to the Restated Certificate is attached as Exhibit A to this proxy statement. If the proposed amendment to the Restated Certificate is approved, subject to the discretion of the Board of Directors, as soon as practicable after the Annual Meeting, the Company will file the amendment to the Restated Certificate with the office of the Secretary of State of Delaware to reflect the increase in the authorized number of shares of our common stock. Upon approval and following such filing with the Secretary of State of Delaware, the amendment to the Restated Certificate will become effective on the date it is filed. Our Board reserves the right to abandon or delay the filing of the amendment to the Restated Certificate even if it is approved by the stockholders. If the proposed amendment to the Restated Certificate is approved and becomes effective, the first paragraph of Article FOURTH of our Restated Certificate, which sets forth our currently authorized capital stock, will be amended to read in its entirety as follows:

“FOURTH: The total number of shares of all classes of stock which the Corporation shall have authority to issue is Two Hundred Fifty-Five Million (255,000,000) shares, consisting of (i) Two Hundred Fifty Million (250,000,000) shares of Common Stock, $0.001 par value per share (“Common Stock”), and (ii) Five Million (5,000,000) shares of Preferred Stock, $0.001 par value per share (“Preferred Stock”).”

The affirmative vote of the holders of at least a majority of the shares of common stock entitled to vote at the Annual Meeting will be required to approve this proposal. Abstentions will have the practical effect of a vote against the amendment to the Restated Certificate. Our Board urges stockholders to vote for this proposal as failure to obtain the vote of a majority of outstanding shares may limit the Company’s abilities to operate and execute on future business plans.

Our Board Recommends that You Vote "FOR" the Approval of an Amendment to the Company’s Restated Certificate of Incorporation to Increase the Number of Authorized Shares of Common Stock from 125,000,000 to 250,000,000.

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Burn Rate and Overhang

In setting and recommending to stockholders the number of additional shares to authorize under the Restated Plan, the Board considered the historical number of equity awards granted under the Plan, as well as the Company’s burn rate. Burn rate provides a measure of the potential dilutive impact of our equity award program which we calculate by dividing the number of shares subject to equity awards granted during the year by the basic weighted average number of shares outstanding. Set forth below is a table that reflects our burn rate for the 2019, 2020 and 2021 fiscal years, as well as an average over those years.

An additional metric that we use to measure the cumulative dilutive impact of our equity program is fully diluted overhang (the sum of (1) the number of shares subject to equity awards outstanding, but not exercised or settled and (2) the number of shares available to be granted, divided by the sum of (1) the total common shares outstanding as of April 14, 2022, (2) the number of shares subject to equity awards outstanding but not exercised or settled, and (3) the number of shares available to be granted). As of April 14, 2022, there were 14,361,039 shares underlying all equity awards outstanding, 922,694 shares available for future awards, and 71,360,039 common shares outstanding. Accordingly, our approximate overhang as of April 14, 2022 was 17.64% as a percent of fully-diluted common shares outstanding. If the Restated Plan is approved, our approximate potential overhang (as a percent of fully diluted shares outstanding) as of that date would increase to 24.98% and then will decline over time.

Our fully diluted overhang from outstanding awards only of 16.57% of as of April 14, 2022 is a function of historical factors such as our options-focused grant strategy, limited exercise relief, benchmarking equity compensation sharing rates against smaller-cap peers in the past when we were a smaller company and utilizing non-dilutive

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financings. For example, we have traditionally utilized stock options within our executive compensation program to encourage the execution of our long-term growth strategy. In 2021, our Chief Executive Officer’s and named executive officers’ annual equity awards were composed of approximately 80% options and 20% restricted stock units, respectively, based upon the grant date fair value of the awards. Approximately 25% of our fully diluted overhang on April 14, 2022 was in vested, in-the-money stock options (approximately 3.81 million options), and our overhang would be 13.85% rather than 17.64% if these options were exercised. To the extent the vested options are out of the money, as some are, they also provide a strong performance incentive that is well-aligned with the interests of our stockholders – and if our performance does not translate to improved share price, the options will expire for no consideration, in accordance with their terms and therefore not dilute our stockholders. Additionally, we have utilized non-dilutive financings, such as our convertible notes issuances in 2015 and 2019, to partially fund our operations and expenses. If we had sold shares of our common in the companies with whichstock to raise such capital instead, we competewould have more fully diluted shares outstanding and a lower overhang.

Request for talent, our Board has adopted the Amended ESPP.Stockholder Approval

A majority of the voting power of the shares of common stock cast on this matter is required to approve this proposal. Our Board urges stockholders to vote for this proposal as failure to obtain the required vote may limit the Company’s ability to attract, retain and motivate talented employees.

Our Board Recommends that You Vote "FOR""FOR" the Approval of an Amendment to the Company’s 2016 Employee Stock Purchase Plan to Increase the Number of Authorized Shares of Common Stock under the Plan from 1,000,000 to 2,000,000.Proposed Amended and Restated 2013 Long-Term Incentive Plan.

Description of the Amended ESPPRestated Plan

The following is a brief summary of the Amended ESPP. Thekey provisions of the Restated Plan, as it would become effective if the stockholders approve this proposal. This summary does not purport to be a complete description of all the provisions of the Restated Plan. A copy of the Restated Plan has been filed with this proxy statement as Exhibit A, and the following description is only a summary of the material terms of the Amended ESPP, andRestated Plan is qualified in its entirety by reference to the Amended ESPP, a copy of which is attachedthat Exhibit. References to our Board in this proxy statement as Exhibit B. You can request a copy of the Amended ESPP by writing to PTC Therapeutics, Inc., Attn: Corporate Communications, 100 Corporate Court, South Plainfield, New Jersey 07080. A copy of the Amended ESPP, which is attached to the electronic copy of this proxy statement filed with the SEC, also may be accessed from the SEC's home page (www.sec.gov).

Eligibility

All employees of the Company andsummary includes our Compensation Committee or any subsidiary of the Company designatedsimilar committee appointed by our Board or Compensation Committee are eligibleour officers, to participate in the Amended ESPP providedextent that they work more than twenty (20) hours per week and for more than five (5) months in a calendar year, are employees for at least two (2) years prior to enrolling in the Amended ESPP and are employees onBoard’s powers or authority under the first day of the applicable offering period; provided, that we may permit employees who work fewer hours per week, fewer months per calendar year or whoRestated Plan have been employed for a shorter period of time priordelegated to participating in the Amended ESPP,such committee or officers, in accordance with the termsRestated Plan.

Types of Awards; Shares Available for Awards; Share Counting Rules

The Restated Plan provides for the grant of incentive stock options intended to qualify under Section 422 of the Amended ESPP, Section 423Internal Revenue Code of 1986, as amended, or the Code, nonstatutory stock options, SARs, restricted stock, restricted stock units, and guidelines thatother stock-based awards, which we establishcollectively refer to as awards.

Subject to adjustment in the event of stock splits, stock dividends or similar events, awards may be made under the Amended ESPP. No employee canRestated Plan (any or all of which awards may be granted an optionin the form of incentive stock options) for up to a number of shares of our common stock as is equal to the sum of:

Shares of our common stock issued under the Restated Plan may consist in whole or in part of authorized but unissued shares or treasury shares.

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The Restated Plan provides that the Amended ESPP that would resultsum of all cash retainers and the reported value of equity compensation provided to the pool of all incumbent non-employee directors for their Board service in a given year may not exceed the employee owningDirector Pool Limit. Newly-appointed or elected non-employee directors will not be subject to the Director Pool Limit during their first year of service and may receive a combination of cash retainers and equity compensation in connection with their initial appointment or election to the Board of up to two (2) times the average incumbent director compensation.

For purposes of counting the number of shares available for the grant of awards under the Restated Plan, all shares of common stock and/or options to purchase common stock representing five percent or more of the total combined voting power or value for all classes of our outstanding capital stock. As of March 31, 2021, approximately 957 employees would have been eligible to participate in the Amended ESPP, including our currently employed named executive officers.

Amended ESPP Operation

The Amended ESPP permits eligible employees to purchase shares of our common stock at a discount. Eligible employees may elect to participatecovered by completing an enrollment form, timely filing it with our payroll office and authorizing after-tax payroll deductions from their pay. Participants can elect to contribute from 1 to 15 percent (or such higher or lower maximum percentage as we may determine in accordance with the terms of the Amended ESPP, Section 423 of the Code and guidelines that we establish under the Amended ESPP), in whole percentages only, of their compensation (as defined in the Amended ESPP) received on each pay day during the offering period. Our Board or Compensation Committee may also, in its discretion, establish a different minimum payroll deduction percentage.

The Amended ESPPSARs will be implemented by consecutive six (6) month offering periods. Our Board or Compensation Committeecounted against the number of shares available for the grant of awards. However, SARs that may be settled only in its discretion, choosecash will not be so counted. In addition, if we grant a different offering period of not more than twenty-seven (27) months.

Offering periods will begin at such time as our Compensation Committee may determine and establishSAR in the Amended ESPP's guidelines. The guidelines currently contemplate that offering periods will begin on the first day on which national stock exchanges and Nasdaq are open for trading on or after July 1 and January 1 of each year. On the first day of each offering period, each employee who is enrolled in the Amended ESPP will automatically receivetandem with an option to purchase, onfor the last business day of the offering period, up to thatsame number of shares of our common stock determinedand provide that only one such award may be exercised, which we refer to as a tandem SAR, only the shares covered by multiplying $2,083the option, and not the shares covered by the tandem SAR, will be so counted, and the expiration of one in connection with the other’s exercise will not restore shares to the Restated Plan.

Shares covered by awards under the Restated Plan that expire or are terminated, surrendered, or canceled without having been fully exercised or are forfeited in whole or in part (including as the result of shares subject to such award being repurchased by us at the original issuance price pursuant to a contractual repurchase right) or are settled in cash or that otherwise result in any shares not being issued will again be available for the grant of awards under the Restated Plan. Further, shares of common stock delivered (by actual delivery, attestation, or net exercise) to us by a participant to exercise an award or to satisfy tax withholding obligations (including shares retained from the award creating the tax obligation) will be added to the number of full monthsshares available for the grant of awards under the Restated Plan. However, in the plan periodcase of incentive stock options, the share counting rules described in this paragraph will be subject to any limitations under the Code.

In connection with a merger or consolidation of an entity with us or our acquisition of property or stock of an entity, our Board may grant awards under the Restated Plan in substitution for any options or other stock or stock-based awards granted by such entity or an affiliate thereof on such terms as our Board determines appropriate in the circumstances, notwithstanding any limitation on awards contained in the Restated Plan. No such substitute awards will count against the overall share limit or sublimit contained in the Restated Plan, except as required by reason of Section 422 and dividing the result by the closing price of our common stock on the first dayrelated provisions of the offering period, or such lesser numberCode.

Descriptions of shares set byAwards

Options. Optionees receive the Board or Compensation Committee. We refer to these as the option shares.

However, no eligible employee may be granted an option under the Amended ESPP that permits the employee's rightsright to purchase shares under the Amended ESPP to accrue at a rate that exceeds $25,000 in fair market value (based on the value of the stock on the first day of the offering period) of our common stock in any given calendar year in which such option is outstanding at any time.

Unless a participant withdraws from the Amended ESPP, the participant's option will be exercised automatically on the last business day of the offering period as to the largest whole number of shares that are exercisable and can be purchased with the deductions accumulated as of the last business day of the offering period.

Our Board or Compensation Committee will determine the purchase price of each of the shares purchased in a given offering period. The purchase price will be at least 85% of (i) the closing price of a share of our common stock on the first business day of the offering period or the last business day of the offering period, whichever is lower or (ii) the closing price of a share of our common stock on the last business day of the offering period. If the totalspecified number of shares of common stock with respect to which options are to be exercised exceeds the number of shares remaining available for issuance under the Amended ESPP, we will only issue to participants in that offering that number of shares remaining available for issuance, onat a pro-rata basis.

All payroll deductions received or held by the Company under the Amended ESPP may be used by us for any corporate purpose,specified exercise price and we will not be obligated to segregate such payroll deductions. No interest will accrue on the payroll deductions (except as our Board or Compensation Committee may otherwise provide), and an employee participating in the Amended ESPP may not increase or decrease payroll deductions, except as permitted by the Amended ESPP. Employees may purchase common stock under the Amended ESPP only through payroll deductions. A participant's payroll deduction elections remain in effect for successive offering periods. Except to the extent provided by our Board or Compensation Committee in accordance with the Amended ESPP, Section 423 of the Code and guidelines with respect to the Amended ESPP a participant's payroll deduction may be decreased, increased or terminated by the participant only with respect to the next offering period. A participant may decrease or increase the

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law and provided for in the applicable option agreement or approved by our Board, in its sole discretion, by any other lawful means, or (vi) by any combination of these forms of payment. No option granted under the Restated Plan may contain a provision entitling the participant to the automatic grant of additional options in connection with any exercise of the original option. No options granted under the Restated Plan may provide for the payment or accrual of dividend equivalents.

Stock Appreciation Rights. A SAR is an award entitling the holder, upon exercise, to receive a number of shares of our common stock, or cash (or a combination of shares of our common stock and cash) determined by reference to appreciation, from and after the date of grant, in the fair market value of a share of our common stock over the measurement price. The Restated Plan provides that the measurement price of a SAR may not be less than the fair market value of our common stock on the date the SAR is granted (provided, however, that if our Board approves the grant of a SAR effective as of a future date, the measurement price shall not be less than 100% of the fair market value on such future date) and that SARs may not be granted with a term in excess of 10 years. No SARs granted under the Restated Plan may contain a provision entitling the participant to the automatic grant of additional SARs in connection with any exercise of the original SAR. No SARs granted under the Restated Plan may provide for the payment or accrual of dividend equivalents.

Limitation on Repricing of Options or SARs. With respect to options and SARs, unless such action is approved by our stockholders or otherwise permitted under the terms of the Restated Plan in connection with certain changes in capitalization and reorganization events, we may not (1) amend any outstanding option or SAR granted under the Restated Plan to provide an exercise price or measurement price per share that is lower than the then-current exercise price or measurement price per share of such outstanding option or SAR, (2) cancel any outstanding option or SAR (whether or not granted under the Restated Plan) and grant in substitution therefor new awards under the Restated Plan (other than certain substitute awards issued in connection with an acquisition by us, described above) covering the same or a different number of shares of our common stock and having an exercise price or measurement price per share lower than the then-current exercise price or measurement price per share of the canceled option or SAR, (3) cancel in exchange for a cash payment any outstanding option or SAR with an exercise price or measurement price per share above the then-current fair market value of our common stock, or (4) take any other action under the Restated Plan that constitutes a “repricing” within the meaning of the rules of the Nasdaq Stock Market or any other exchange or marketplace on which our stock is listed or traded.

Restricted Stock Awards. Restricted stock awards entitle recipients to acquire shares of our common stock, subject to our right to repurchase all or part of such shares at their issue price or other stated or formula price (or to require forfeiture of such shares if issued at no cost) in the event that the conditions specified in the applicable award are not satisfied prior to the end of the applicable restriction period established for such award. Any dividends (whether paid in cash, stock or property) declared and paid by us with respect to shares of restricted stock will be paid to the participant only if and when such shares become free from the restrictions on transferability and forfeitability that apply to such shares. No interest will be paid on such dividends.

Restricted Stock Unit Awards. Restricted stock units, or RSUs, entitle the recipient to receive shares of our common stock, or cash equal to the fair market value of such shares, to be delivered at the time such award vests pursuant to the terms and conditions established by our Board. Our Board may provide that settlement of RSUs will be deferred, on a mandatory basis or at the election of the participant in a manner that complies with Section 409A of the Code. A participant has no voting rights with respect to any RSU. Our Board may provide that a grant of RSUs may provide the participant with the right to receive an amount equal to any dividends or other distributions declared and paid on an equal number of outstanding shares of our common stock. Any such dividend equivalents may be credited to an account for the participant and may be settled in cash and/or shares of our common stock, in each case to the extent provided in the applicable award agreement. Dividend equivalents with respect to RSUs will be subject to the same restrictions on transfer and forfeitability as the RSUs with respect to which such dividend equivalents are awarded. No interest will be paid on any such dividend equivalents.

Other Stock-Based Awards. Under the Restated Plan, our Board may grant other awards of shares of our common stock, and other awards that are valued in whole or in part by reference to, or are otherwise based on, shares of our common stock or other property, having such terms and conditions as our Board may determine. We refer to these types

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of awards as other stock-based awards. Other stock-based awards may be available as a form of payment in settlement of other awards granted under the Restated Plan or as payment in lieu of compensation to which a participant is otherwise entitled. Other stock-based awards may be paid in shares of our common stock or in cash, as our Board may determine. The award agreement of an other stock-based award may provide the holder of an other stock-based award with the right to receive dividend equivalents. Dividend equivalents may be credited to an account for the participant and may be settled in cash and/or shares of our common stock, in each case to the extent provided in the applicable award agreement. Dividend equivalents with respect to other stock-based awards will be subject to the same restrictions on transfer and forfeitability as the other stock-based award with respect to which they are awarded. No interest will be paid on any such dividend equivalents.

Eligibility to Receive Awards

All of our employees, officers, and directors, as well as our consultants and advisors, are eligible to receive awards under the Restated Plan. However, incentive stock options may only be granted to our employees, employees of our present or future parent or subsidiary corporations, and employees of any other entities the employees of which are eligible to receive incentive stock options under the Code.

Transferability of Awards

Awards may not be sold, assigned, transferred, pledged or otherwise encumbered by the person to whom they are granted, either voluntarily or by operation of law, except by will or the laws of descent and distribution or, other than in the case of an incentive stock option, pursuant to a qualified domestic relations order. During the life of the participant, awards are exercisable only by the participant. However, our Board may permit or provide in an award for the gratuitous transfer of the award by the participant to or for the benefit of any immediate family member, family trust or other entity established for the benefit of the participant and/or an immediate family member thereof if we would be eligible to use a Form S-8 under the Securities Act of 1933, as amended, for the registration of the sale of the common stock subject to such award to the proposed transferee. Further, we are not required to recognize any transfer until such time as the participant and the permitted transferee have, as a condition to the transfer, delivered to us a written instrument in form and substance satisfactory to us confirming that such transferee will be bound by all of the terms and conditions of the award. None of the restrictions described in this paragraph prohibit a transfer from the participant to the Company.

No Rights as a Stockholder; Clawback

No participant will have any rights as a stockholder with respect to any shares of common stock to be distributed with respect to an award granted under the Restated Plan until becoming a record holder of such shares, subject to the terms of an award agreement. In accepting an award granted under the Restated Plan on or after the effective date of the Restated Plan, a participant agrees to be bound by any clawback policy that the Company has in effect or may adopt in the future.

Administration

The Restated Plan will be administered by our Board. Our Board has the authority to grant awards and to adopt, amend and repeal the administrative rules, guidelines and practices relating to the Restated Plan that it deems advisable and to construe and interpret the provisions of the Restated Plan and any award agreements entered into under the Restated Plan. Our Board may correct any defect, supply any omission or reconcile any inconsistency in the Restated Plan or any award in the manner and to the extent it deems expedient and will be the sole and final judge of such expediency. All decisions by our Board made under the Restated Plan will be made in our Board’ sole discretion and will be final and binding on all persons having or claiming any interest in the Restated Plan or in any award.

Pursuant to the terms of the Restated Plan, our Board may delegate any or all of its powers under the Restated Plan to one or more committees or subcommittees of our Board. Additionally, subject to any requirements of applicable law, our Board may delegate to one or more of our officers the power to grant awards (subject to any limitations under the Restated Plan) to our employees or officers and to exercise other powers under the Restated Plan as our Board may determine. However, no officer will be authorized to grant awards to any “executive officer” of the Company (as defined by Rule 3b-7 under the Securities Exchange Act of 1934, as amended, or the Exchange Act) or to any “officer” of the

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Company (as defined by Rule 16a-1(f) under the Exchange Act. Our Board has authorized the Compensation Committee to administer certain aspects of the Restated Plan. Awards granted to non-employee directors must be granted and administered by a committee of our Board, all of the members of which are independent directors as defined by Section 5605(a)(2) of the Nasdaq Marketplace Rules.

Subject to any applicable limitations contained in the Restated Plan, our Board, the Compensation Committee, or any other committee or officer to whom our Board delegates authority, as the case may be, selects the recipients of awards and determines (i) the number of shares thatof common stock, cash or other consideration covered by awards and the terms and conditions of such awards, including the dates upon which such awards become exercisable or otherwise vest, (ii) the exercise or measurement price of awards, if any, and (iii) the duration of awards.

Except as otherwise provided by the Restated Plan, each award under the Restated Plan may be purchasedmade alone or in addition or in relation to any other award. The terms of each award need not be identical, and our Board need not treat participants uniformly. Our Board will determine the effect on an award of the disability, death, termination or other cessation of employment or other status, authorized leave of absence or other change in the future pursuantemployment or other status of a participant, and the extent to which, and the Amended ESPP are not currently determinable.period during which, the participant (or the participant’s legal representative, conservator, guardian or designated beneficiary) may exercise rights under an award. Our Board may at any time provide that any award shall become immediately exercisable in whole or in part, free of some or all restrictions or conditions or otherwise realizable in whole or in part, as the case may be.

WeIn the event of any stock split, reverse stock split, stock dividend, recapitalization, combination of shares, reclassification of shares, spin-off or other similar change in capitalization or event, or any dividend or distribution to holders of our common stock, other than an ordinary cash dividend, we are required to make equitable adjustments (or make substituted awards, as applicable), in the manner determined by our Board, to (i) the number and class of securities available under the Amended ESPP,Restated Plan, (ii) the share limitations undercounting rules set forth in the Amended ESPPRestated Plan, (iii) the number and class of securities and exercise price per share of each outstanding option, (iv) the share- and per-share provisions and the measurement price of each outstanding SAR, (v) the number of shares subject to and the repurchase price per share subject to each outstanding award of restricted stock and RSUs, and (vi) the share and per-share-related provisions and the purchase price, forif any, of each outstanding other stock-based award.

We will indemnify and hold harmless each director, officer, employee or agent to whom any duty or power relating to the administration or interpretation of the Restated Plan has been or will be delegated against any cost or expense (including attorneys’ fees) or liability (including any sum paid in settlement of a claim with our Board’s approval) arising out of any act or omission to act concerning the Restated Plan unless arising out of such person’s own fraud or bad faith.

Amendment of awards. Subject to the provisions of the Restated Plan with respect to repricing outstanding stock options or SARs, our Board may amend, modify or terminate any outstanding award, including but not limited to, substituting therefor another award of the same or a different type, changing the date of exercise or realization, and converting an offering periodincentive stock option to a nonstatutory stock option. The award holder’s consent to any such action will be required unless our Board determines that the action, taking into account any related action, does not materially and adversely affect the award holder’s rights under the Amended ESPP to reflect stock splits, reverse stock splits, stock dividends, recapitalizations, combinationsRestated Plan or the change is otherwise permitted under the terms of shares, reclassifications of shares, spin-offs and other similar changesthe Restated Plan in connection with a change in capitalization or eventsreorganization event.

Reorganization Events

The Restated Plan contains provisions addressing the consequences of any reorganization event. A reorganization event is defined under the Restated Plan as (a) any merger or any dividendsconsolidation of us with or distributions to holdersinto another entity as a result of which all of our common stock other than ordinaryis converted into or exchanged for the right to receive cash, dividends.

In connection with a mergersecurities or other property, or is canceled, (b) any transfer or disposition of all of our common stock for cash, securities or other property pursuant to a share exchange or other transaction or (c) our liquidation or dissolution.

Provisions Applicable to Awards Other than Restricted Stock. Under the Restated Plan, if a reorganization event (as defined in the Amended ESPP), our Board or a committee appointed byoccurs, our Board may take any one or more of the following actions as to all or any (or any portion of) outstanding options to purchase shares

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awards other than restricted stock under the Amended ESPP on such terms as our Board determines (except to the extent specifically provided otherwise in an applicable award agreement or committee determines:

​Provisions for Foreign Participants

Our Board may establish one or more sub-plans under the Restated Plan to satisfy applicable securities, tax or other laws of various jurisdictions. Our Board will establish such sub-plans by adopting supplements to the Restated Plan containing any limitations on our Board’s discretion under the Restated Plan and any additional terms and conditions not otherwise inconsistent with the Restated Plan as the Board deems necessary or desirable. All supplements adopted by our Board will be deemed to be part of the Restated Plan, but each supplement will only apply to participants within the affected jurisdiction.

Amendment or Termination

If we receive stockholder approval of the Restated Plan, no award may be granted under the Restated Plan after June 7, 2032, but awards previously granted may extend beyond that date. Our Board may amend, suspend or terminate the Restated Plan or any portion of the Restated Plan at any time, except that (i) no amendment may be made to the plan to permit an option or SAR to be repriced without stockholder approval and (ii) no amendment that would require stockholder approval under the rules of the national securities exchange on which the Company then maintains its primary listing will be effective unless and until such amendment has been approved by our stockholders. If at any time the approval of our stockholders is required as to any other modification or amendment under Section 422 of the Code or any successor provision with respect to incentive stock options, our Board may not effect such modification or amendment without such approval. Unless otherwise specified in the amendment, any amendment to the Restated Plan adopted in accordance with the procedures described above will apply to, and be binding on the holders of, all awards outstanding under the Restated Plan at the time the amendment is adopted, provided that our Board determines that such amendment, taking into account any related action, does not materially and adversely affect the rights of participants

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Administration

The Amended ESPP shallunder the Restated Plan. No award will be administered by our Board or by a committee appointed by the Board. Our Board or such committee has authority to make rules and regulations for the administrationmade that is conditioned on stockholder approval of the Amended ESPP, and its interpretation and decisions with respectany amendment to the Amended ESPP shall be final and conclusive.

The Board or such committee may delegate to one or more officers ofRestated Plan unless the Company the authority to implement and administer the Amended ESPP, subject to the terms of the Amended ESPP and any guidelines approved by the Board or such committee. The Board has appointed the Compensation Committee to administer the ESPP, and the Compensation Committee has delegated authority over certain administrative matters with respect to the ESPP to the Company's Employee Benefit Plan Committee, subject to the terms of the ESPP and the guidelines adopted by the Compensation Committee. Such delegationsaward provides that (i) it will remain in effect if the Amended ESPP is approved by the stockholders.

Our Board or Compensation Committee has the ability to change offering periods (including the commencement dates and length thereof) with respect to future offerings without stockholder approval. Our Board may terminate or amendbe forfeited if stockholder approval of such amendment is not obtained within no more than 12 months from the Amended ESPP at any timedate the award was granted and for any reason. The Board may amend the Amended ESPP at any time, but the plan(ii) it may not be amendedexercised or settled (or otherwise result in any way that will cause rights issued thereunder to fail to meet the requirements for employee stock purchase plans as defined in Section 423 of the Code including stockholder approval if required.

Our Board or the Compensation Committee may allow employees who are citizens or residents of foreign jurisdictions to participate in an offering period or establish sub-plans for the benefit of such foreign employees to the extent such actions are in compliance with Section 423 of the Code.

New Plan Benefits

Benefits and purchasesissuance of shares of our common stockstock) prior to the receipt of such stockholder approval.

If stockholders do not approve the adoption of the Restated Plan, the Restated Plan will not go into effect, and the Company will not grant any awards under the Amended ESPP depend on electionsRestated Plan. In this event, awards will continue to be made by employeesunder the Plan until the expiration of the Plan in accordance with its terms and the fair market valueBoard will consider whether to adopt alternative arrangements based on its assessment of ourthe needs of the Company.

Plan Benefits

As of April 14, 2022, approximately 1,322 persons were eligible to receive awards under the Restated Plan, including the Company’s 1,215 employees (excluding officers), 7 officers (all of whom are also employees), 9 directors (excluding the Chief Executive Officer, who is an officer), and 9 consultants. As of April 14, 2022, the Company had 82 advisors (excluding consultants). The granting of awards under the Restated Plan is discretionary, and the Company cannot now determine the number or type of awards to be granted in the future to any particular person or group.

On April 27, 2022 the last reported sale price of the Company common stock on datesthe Nasdaq Stock Market was $37.15.

New Plan Benefits

Our executive officers and directors have an interest in approval of the future. As a result,Restated Plan because it is not possiblerelates to determine the issuance of equity awards for which executive officers and directors may be eligible. The benefits that will be received byawarded or paid under the Restated Plan to executive officers and other employees in the futuredirectors cannot currently be determined. Awards granted under the Amended ESPP.

For illustrative purposes only, the following table sets forth certain information regarding the number of shares of our common stock purchased during the fiscal year 2020 offering periods pursuantRestated Plan to our ESPP by each of (i) the NEOs identified in the Summary Compensation Table of this proxy statement, (ii) all current executive officers as a group, and (iii) all employees, other than executive officers, as a group. Non-executive membersdirectors are within the discretion of ourthe Board, areand the Board has not eligible to participate in the ESPP.determined future awards or who might receive them.

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SinceAggregate Past Grants Under the ESPP was approved by our stockholders in 2016: Dr. Peltz has purchased 0Plan

The table below shows, as to each Named Executive Officer and the various indicated groups, the aggregate number of shares of our common stock subject to option grants, restricted stock grants and RSU grants under the ESPP, Ms. Hill has purchased 0 shares of our common stock underPlan since the ESPP, Dr. Almstead has purchased 2,490 shares of our common stock under the ESPP, Mr. Boulding has purchased 2,490 shares of our common stock under the ESPP, Mr. Pauwels has purchased 3,774 shares of our common stock under the ESPP, Mr. Souza has purchased 3,505 shares of our common stock under the ESPP, all of our current executive officers, as a group have purchased 13,068 shares of our common stock under the ESPP, all of our non-executive directors and director nominees, as a group have purchased 0 shares of our common stock under the ESPP and all of our employees, other than current executive officers, as a group have purchased 627,765 shares of our common stock under the ESPP.Plan’s inception through April 14, 2022.

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U.S. Federal Income Tax Consequences

The following generally summarizesis a summary of the United States federal income tax consequences that generally will arise with respect to participation in the Amended ESPP and with respect to the sale of common stock acquiredawards granted under the plan.Restated Plan. This summary is based on the federal tax laws in effect as of the date of this proxy statement. The Amended ESPP is intended to qualify as an "employee stock purchase plan" as defined in Section 423 of the Code. This summary assumes that the Amended ESPP complies with Section 423 of the Code. Further,In addition, this summary assumes that all awards are exempt from, or comply with, the purchase price for shares is 85%rules under Section 409A of the closing price of a share of our common stock on the first day of the offering period or the last day of the offering period, whichever is lower.Code regarding nonqualified deferred compensation. Changes to these laws could alter the tax consequences described below.

Tax Consequences to Participants

Incentive Stock Options. A participant will not have income upon enrolling in the Amended ESPPgrant of an incentive stock option. Also, except as described below, a participant will not have income upon exercise of an incentive stock option if the participant has been employed by the Company or upon purchasingits corporate parent or 50% or majority-owned corporate subsidiary at all times beginning with the option grant date and ending three months before the date the participant exercises the option. If the participant has not been so employed during that time, then the participant will be taxed as described below under “Nonstatutory Stock Options.” The exercise of an incentive stock atoption may subject the end of a purchase period. participant to the alternative minimum tax.

A participant maywill have both compensation income and a capital gain or loss upon the sale of the stock that was acquired under an incentive stock option at a profit (if sales proceeds exceed the Amended ESPP.exercise price). The amount of each type of income and loss will depend on whetherwhen the participant disposes ofsells the stock instock. If a qualifying or disqualifying disposition. A qualifying disposition is when the participant sells the stock more than two years after the commencement of the offering during which the stockoption was purchasedgranted and more than one year after the date on which the participant purchased the stock at a profit (i.e., the sales proceeds exceed the purchase price). In a qualifying disposition, the participant will have compensation income equal to the lesser of:

Any profit in excess of compensation income will be long-term capital gain. If the participant sells the stock at a loss (i.e., if sales proceeds are less than the purchase price) after satisfying these waiting periods, then the loss will be a long-term capital loss.

If the participant sells the stock prior to satisfying these waiting periods, then he or shethe participant will have engaged in a disqualifying disposition. Upondisposition and a disqualifying disposition,portion of the profit will be ordinary income and a portion may be capital gain. This capital gain will be long-term if the participant has held the stock for more than one year and otherwise will be short-term. If a participant sells the stock at a loss (sales proceeds are less than the exercise price), then the loss will be a capital loss. This capital loss will be long-term if the participant held the stock for more than one year and otherwise will be short-term.

Nonstatutory Stock Options. A participant will not have income upon the grant of a nonstatutory stock option. A participant will have compensation income upon the exercise of a nonstatutory stock option equal to the value of the stock on the day he or she purchasedthe participant exercised the option less the exercise price. Upon sale of the stock, less the purchase price. The participant also will have capital gain or loss equal to the difference between the sales proceeds and the value of the stock on the day the

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option was exercised. This capital gain or loss will be long-term if the participant has held the stock for more than one year and otherwise will be short-term.

Stock Appreciation Rights. A participant will not have income upon the grant of a SAR. A participant generally will recognize compensation income upon the exercise of a SAR equal to the amount of the cash and the fair market value of any stock received. Upon the sale of the stock, the participant will have capital gain or loss equal to the difference between the sales proceeds and the value of the stock on the day he or she purchased the stock.SAR was exercised. This capital gain or loss will be long-term if the participant has held the stock for more than one year and short-termotherwise will be short-term.

Restricted Stock Awards. A participant will not have income upon the grant of restricted stock unless an election under Section 83(b) of the Code is made within 30 days of the date of grant. If a timely 83(b) election is made, then a participant will have compensation income equal to the value of the stock less the purchase price. When the stock is sold, the participant will have capital gain or loss equal to the difference between the sales proceeds and the value of the stock on the date of grant. If the participant does not make an 83(b) election, then when the stock vests the participant will have compensation income equal to the value of the stock on the vesting date less the purchase price. When the stock is sold, the participant will have capital gain or loss equal to the sales proceeds less the value of the stock on the vesting date. Any capital gain or loss will be long-term if the participant held the stock for more than one year and otherwise will be short-term.

Restricted Stock Units. A participant will not have income upon the grant of an RSU. A participant is not permitted to make a Section 83(b) election with respect to an award of RSUs. When an RSU vests, the participant will have income on the vesting date in an amount equal to the fair market value of the stock on the vesting date less the purchase price, if any. When the stock is sold, the participant will have capital gain or less.loss equal to the sales proceeds less the value of the stock on the vesting date. Any capital gain or loss will be long-term if the participant held the stock for more than one year and otherwise will be short-term.

Other Stock-Based Awards. The tax consequences associated with any other stock-based award granted under the Restated Plan will vary depending on the specific terms of such award. Among the relevant factors are whether or not the award has a readily ascertainable fair market value, whether or not the award is subject to forfeiture provisions or restrictions on transfer, the nature of the property to be received by the participant under the award, and the participant’s holding period and tax basis for the award or underlying common stock.

Tax Consequences to Us

the Company. There will be no tax consequences to usthe Company except that wethe Company will be entitled to a deduction when a participant recognizeshas compensation income, upon a disqualifying disposition. Any such deduction will be subject to the limitations of Section 162(m) of the Code.

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PROPOSAL 4:3: RATIFICATION OF SELECTION OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

Our Audit Committee has appointed the firm of Ernst & Young LLP, an independent registered public accounting firm, to audit our books, records and accounts for the fiscal year ending December 31, 2021.2022. This appointment is being presented to the stockholders for ratification at the Annual Meeting.

Ernst & Young LLP has served as our auditor consecutively since 2010, and has served as our independent registered public accounting firm beginning in connection with our initial public offering in 2013. Ernst & Young LLP has no direct or indirect material financial interest in our Company or our subsidiaries. Representatives of Ernst & Young LLP are expected to be present at the Annual Meeting and will be given the opportunity to make a statement on the firm’s behalf if they so desire. The representatives also will be available to respond to appropriate questions.

Our Audit Committee is solely responsible for selecting our independent registered public accounting firm for 2021.2022. Although we are not required to submit the appointment to a vote of the stockholders, our Board believes that it is appropriate as a matter of good corporate governance to request that the stockholders ratify the appointment of Ernst & Young LLP as our independent registered public accounting firm.

If the stockholders do not ratify the appointment, our Audit Committee will investigate the reasons for stockholder rejection and may reconsider its appointment of Ernst & Young LLP as our independent registered public accounting firm for 20212022 and may appoint another independent registered public accounting firm. Even if the appointment is ratified, our Audit Committee in their discretion may direct the appointment of a different independent registered public accounting firm at any time during the year if they determine that such a change would be in the best interests of our Company and our stockholders.

A majority of the voting power of the shares of common stock cast on this matter is required to approve this proposal. Unless otherwise instructed in the proxy, all proxies will be voted "FOR" the ratification of Ernst & Young LLP.

Our Board Recommends that You Vote "FOR" the Ratification of Ernst & Young LLP as our Independent Registered Public Accounting Firm for the Fiscal Year Ending December 31, 2021.2022.

Fees Paid to Independent Registered Public Accounting Firm

The following table sets forth the fees incurred for services performed by Ernst & Young LLP during fiscal years 20202021 and 2019:2020:

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