As of December 31, 2015,2018, we had approximately 14.217 million members in our medical benefit plans, as well as approximately 7.26 million members in our specialty products. During 2015, 73%2018, 81% of our total premiums and services revenue were derived from contracts with the federal government, including 14%15% derived from our individual Medicare Advantage contracts in Florida with the Centers for Medicare and Medicaid Services, or CMS, under which we provide health insurance coverage to approximately 587,400636,800 members as of December 31, 2015.2018.

Humana Inc. was organized as a Delaware corporation in 1964. Our principal executive offices are located at 500 West Main Street, Louisville, Kentucky 40202, the telephone number at that address is (502) 580-1000, and our website address is www.humana.com. We have made available free of charge through the Investor Relations section of our web site our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, proxy statements, and, if applicable, amendments to those reports filed or furnished pursuant to Section 13(a) of the Exchange Act, as soon as reasonably practicable after we electronically file such material with, or furnish it to, the Securities and Exchange Commission.

This Annual Report on Form 10-K, or 20152018 Form 10-K, contains both historical and forward-looking information. See Item 1A. – Risk Factors in this 20152018 Form 10-K for a description of a number of factors that may adversely affect our results or business.

Our medical and specialty insurance products allow members to access health care services primarily through our networks of health care providers with whom we have contracted. These products may vary in the degree to which members have coverage. Health maintenance organizations, or HMOs, include comprehensive managed care benefits generally requirethrough a referral from the member’s primary care provider before seeing certain specialty physicians.participating network of physicians, hospitals, and other providers. Preferred provider organizations, or PPOs, provide members the freedom to choose aany health care provider without requiring a referral.provider. However PPOs generally require the member to pay a greater portion of the provider’s fee in the event the member chooses not to use a provider participating in the PPO’s network. Point of Service, or POS, plans combine the advantages of HMO plans with the flexibility of PPO plans. In general, POS plans allow members to choose, at the time medical services are needed, to seek care from a provider within the plan’s network or outside the network. In addition, we offer services to our health plan members as well as to third parties that promote health and wellness, including pharmacy solutions, provider, home based, and clinical programs, as well as services and capabilities to advance population health. At the core of our strategy is our integrated care delivery model, which unites quality care, high member engagement, and sophisticated data analytics. Three core elements of the model are to improve the consumer experience by simplifying the interaction with us, engaging members in clinical programs, and offering assistance to providers in transitioning from a fee-for-service to a value-based arrangement. Our approach to primary, physician-directed care for our members aims to provide quality care that is consistent, integrated, cost-effective, and member-focused. The model is designed to improve health outcomes and affordability for individuals and for the health system as a whole, while offering our members a simple, seamless healthcare experience. The discussion that follows describes the products offered by each of our segments.

The products offered by our Healthcare Services segment are key to our integrated care delivery model. This segment is comprised of stand-alone businesses that offer services including pharmacy solutions, provider services, home basedclinical care services, clinical programs, and predictive modeling and informatics services to other Humana businesses, as well as external health plan members, external health plans, and other employers or individuals and are described in the discussion that follows. Our intersegment revenue is described in Note 17 to the consolidated financial statements included in Item 8. – Financial Statements and Supplementary Data. The following table presents our services revenue for the Healthcare Services segment by line of business for the year ended December 31, 2015:2018:

We operate full-service, multi-specialty medical centers in a number of states, primarily in Florida and Texas, staffed by primary care providers and medical specialists practicing cardiology, endocrinology, geriatric medicine, internal medicine, ophthalmology, neurology, and podiatry. Our care delivery subsidiaries operate our medical center business through both employed physicians and care providers, and through third party management service organizations with whom we contract to arrange for and manage certain clinical services.

We also operate Transcend, a Medical Services Organization, or MSO, that coordinates medical care for Medicare Advantage beneficiaries primarily in Florida, Arkansas, Alabama and Kansas.four states. Transcend provides resources in care coordination, financial risk management, clinical integration and patient engagement that help physicians improve the patient experience as well as care outcomes. Transcend collaborates with physicians, medical groups and integrated delivery systems to successfully transition to value-based care by engaging, partnering and offering practical services and solutions. Transcend represents a key component of our integrated care delivery model which we believe is scalable to new markets. In addition,

During 2018, we own a noncontrollingacquired the remaining equity interest in MCCI Holdings, LLC, or MCCI, a privately held MSOmanagement service organization and healthcare provider headquartered in Miami, Florida, that primarily coordinates medical care for Medicare Advantage beneficiaries in Florida Texas and Georgia.Texas. In addition, during 2018, we acquired Family Physicians Group, or FPG, which serves Medicare Advantage and Managed Medicaid HMO patients in Greater Orlando, Florida with a footprint that includes clinics located in Lake, Orange, Osceola and Seminole counties. See Note 3 to the consolidated financial statements included in Item 8. - Financial Statements and Supplementary Data.

We are key elementscommitted to the integrated physical and mental health of our integratedmembers. Accordingly, we take a holistic approach to healthcare, offering care delivery model. We believe that technology represents a significant opportunity in health care that positively impacts our members. Our Transcend Insights business focuses on population healthmanagement and wellness programs. These programs use our capabilities across the sector and serves health care systems, physicians and care teams by leveraging actionable data to help improve patient care. We help care teams and patients transition from a reactive approach to care to one that proactively promotes health and long-term wellness. We have enhanced our health information technology capabilities enablingenable us to create a more complete view of an individual’s health, designed to connect, coordinate and simplify health care while reducing costs. These capabilities include our health care analytics engine, which reviews billions of clinical data points on millions of patients each day to provide members, providers, and payers real-time clinical insights to identify evidence-based gaps-in-care, drug safety alerts and other critical health concerns to improve outcomes. Additionally, our technology connects Humana and disparate electronic health record systems to enable the exchange of essential health information in real-time to provide physicians and care teams with a single, comprehensive patient view.

We discontinued substantially all off-exchange individual commercial medical plans effective January 1, 2017, and we focus on the behavioral aspects of a members' health such as managing stress and work/life balance. Humana Behavioral Health takes a holistic, mind-and-body approach to behavioral healthcare to address the whole person, encouraging faster recovery and improving clinical outcomes while reducing costs for both the member and employer.exited our remaining individual commercial medical business effective January 1, 2018.

Other Businesses includes those businesses that do not align with the reportable segments previously described, primarily includes our closed block ofclosed-block long-term care insurance policies, described below. Total premiumswhich was sold in 2018. For a detailed discussion of the sale refer to Note 3 to the consolidated financial statements included in Item 8. – Financial Statements and services revenue for our Other Businesses was $49 million, or 0.1% of consolidated premiums and services revenue for the year ended December 31, 2015.

We provide our members with access to health care services through our networks of health care providers whom we employ or with whom we have contracted, including hospitals and other independent facilities such as outpatient surgery centers, primary care providers, specialist physicians, dentists, and providers of ancillary health care services and facilities. These ancillary services and facilities include laboratories, ambulance services, medical equipment services, home health agencies, mental health providers, rehabilitation facilities, nursing homes, optical services, and pharmacies. Our membership base and the ability to influence where our members seek care generally enable us to obtain contractual discounts with providers.

We use a variety of techniques to provide access to effective and efficient use of health care services for our members. These techniques include the coordination of care for our members, product and benefit designs, hospital inpatient management systems, the use of sophisticated analytics, and enrolling members into various care management programs. The focal point for health care services in many of our HMO networks is the primary care provider who, under contract with us, provides services to our members, and may control utilization of appropriate services by directing or approving hospitalization and referrals to specialists and other providers. Some physicians may have arrangements under which they can earn bonuses when certain target goals relating to the provision of quality patient care are met. We have available care management programs related to complex chronic conditions such as congestive heart failure and coronary artery disease. We also have programs for prenatal and premature infant care, asthma related illness, end stage renal disease, diabetes, cancer, and certain other conditions.

We typically contract with hospitals on either (1) a per diem rate, which is an all-inclusive rate per day, (2) a case rate orfor diagnosis-related groups (DRG), which is an all-inclusive rate per admission, or (3) a discounted charge for inpatient hospital services. Outpatient hospital services generally are contracted at a flat rate by type of service, ambulatory payment classifications, or APCs, or at a discounted charge. APCs are similar to flat rates except multiple services and procedures may be aggregated into one fixed payment. These contracts are often multi-year agreements, with rates that are adjusted for inflation annually based on the consumer price index, other nationally recognized inflation indexes, or specific negotiations with the provider. Outpatient surgery centers and other ancillary providers typically are contracted at flat rates per service provided or are reimbursed based upon a nationally recognized fee schedule such as the Medicare allowable fee schedule.

Our contracts with physicians typically are renewed automatically each year, unless either party gives written notice, generally ranging from 90 to 120 days, to the other party of its intent to terminate the arrangement. Most of the physicians in our PPO networks and some of our physicians in our HMO networks are reimbursed based upon a fixed fee schedule, which typically provides for reimbursement based upon a percentage of the standard Medicare allowable fee schedule.

The terms of our contracts with hospitals and physicians may also vary between Medicare and commercial business. A significant portion of our Medicare network contracts, including those with both hospitals and physicians, are tied to Medicare reimbursement levels and methodologies.

We offer providers a continuum of opportunities to increase the integration of care and offer assistance to providers in transitioning from a fee-for-service to a value-based arrangement. These include performance bonuses, shared savings and shared risk relationships. For some of our medical membership, we share risk with providers under capitation contracts where physicians and hospitals accept varying levels of financial risk for a defined set of membership, primarily HMO membership. Under the typical capitation arrangement, we prepay these providers a monthly fixed-fee per

We believe these risk-based models represent a key element of our integrated care delivery model at the core of our strategy. Our health plan subsidiaries may enter into these risk-based contracts with third party providers or our owned provider subsidiaries.

At December 31, 2015,2018, approximately 1,100,0001,128,500 members, or 7.7%6.8% of our medical membership, were covered under risk-based contracts, which provide all member benefits, including 863,000942,000 individual Medicare Advantage members, or 31.3%30.7% of our total individual Medicare Advantage membership.

Physicians under capitation arrangements typically have stop loss coverage so that a physician’s financial risk for any single member is limited to a maximum amount on an annual basis. We typically process all claims and monitor the financial performance and solvency of our capitated providers. However, we delegated claim processing functions under capitation arrangements covering approximately 196,600181,200 HMO members, including 172,000168,900 individual Medicare Advantage members, or 19.9%17.9% of the 863,000942,000 individual Medicare Advantage members covered under risk-based contracts at December 31, 2015,2018, with the provider assuming substantially all the risk of coordinating the members’ health care benefits. Capitation expense under delegated arrangements for which we have a limited view of the underlying claims experience was approximately $768 million,$1.5 billion, or 1.7%3.3% of total benefits expense, for the year ended December 31, 2015.2018. We remain financially responsible for health care services to our members in the event our providers fail to provide such services.

Our accreditation assessment program consists of several internal programs, including those that credential providers and those designed to meet the audit standards of federal and state agencies as well as external accreditation standards. We also offer quality and outcome measurement and improvement programs such as the Health Care Effectiveness Data and Information Sets,Set, or HEDIS, which is used by employers, government purchasers and the National

Providers participating in our networks must satisfy specific criteria, including licensing, patient access, office standards, after-hours coverage, and other factors. Most participating hospitals also meet accreditation criteria established by CMS and/or theThe Joint Commission on Accreditation of Healthcare Organizations.Commission.

Recredentialing of participating providers occurs every two to three years, depending on applicableunless otherwise required by state laws.or federal regulations. Recredentialing of participating providers includes verification of their medical licenses, review of their malpractice liability claims histories, review of their board certifications, if applicable, and review of applicable quality information. A committee composed of a peer group of providers reviews the applications of providers being considered for credentialing and recredentialing.

We requestmaintain accreditation for certain of our health plans and/or departments from NCQA, the Accreditation Association for Ambulatory Health Care and(AAAHC), and/or URAC. Accreditation or external review by an approved organization is mandatory in the states of Florida and Kansas for licensure as an HMO. Additionally, all products sold on the federal and state marketplacesAll Federal Employee Health Benefit Plans are required to be accredited. Certain commercial businesses, likesuch as those impacted by a third-party labor agreement or those where a request is made by the employer, may require or prefer accredited health plans.

NCQA reviews our compliance based on standards for quality improvement, population health management, credentialing, utilization management, network management, member connections, and member rights and responsibilities. We have achieved and maintained NCQA accreditation in mostmany of our commercial, Medicare and Medicaid HMO/POS and PPO markets with enough history and membership, and for many of our PPO markets.wellness program, Go365. Humana’s pharmacy organization is accredited by URAC.

We use various methods to market our products, including television, radio, the Internet, telemarketing, and direct mailings.

At December 31, 2015,2018, we employed approximately 1,6001,500 sales representatives, as well as approximately 1,400 telemarketing representatives who assisted in the marketing of Medicare, including Medicare Advantage and individual commercial health insurancePDP, in our Retail segment and specialty products in our RetailGroup and Specialty segment, including making appointments for sales representatives with prospective members. We have a marketing arrangement with Wal-Mart Stores, Inc., or Wal-Mart, for our individual Medicare stand-alone PDP offering. We also sell group Medicare Advantage products through large employers. In addition, we market our Medicare and individual commercial health insurance and specialty products through licensed independent brokers and agents. For our Medicare products, commissions paid to employed sales representatives and independent brokers and agents are based on a per unit commission structure, regulated in structure and amount by CMS. For our individual commercial health insurance and specialty products, we generally pay brokers a commission based on premiums, with commissions varying by market and premium volume. In addition to a commission based directly on premium volume for sales to particular customers, we also have programs that pay brokers and agents based on other metrics. These include commission bonuses based on sales that attain certain levels or involve particular products. We also pay additional commissions based on aggregate volumes of sales involving multiple customers.

In our Group and Specialty segment, individuals may become members of our commercial HMOs and PPOs through their employers or other groups, which typically offer employees or members a selection of health insurance products, pay for all or part of the premiums, and make payroll deductions for any premiums payable by the employees. We attempt to become an employer’s or group’s exclusive source of health insurance benefits by offering a variety of HMO, PPO, and specialty products that provide cost-effective quality health care coverage consistent with the needs and expectations of their employees or members. In addition, we have begun to offer plans to employer groups through private exchanges. Employers can give their employees a set amount of money and then direct them to a private exchange. There, employees can shop for a health plan and other benefits based on what the employer has selected as options. We use licensed independent brokers, independent agents, digital insurance agencies, and employees to sell our group products. Many of our larger employer group customers are represented by insurance brokers and consultants who assist these groups in the design and purchase of health care products. We pay brokers and agents using the same commission structure described above for our individual commercial health insurance and specialty products.

Beginning inSince 2014, the Patient Protection and Affordability Care Act and The Health Care and Education Reconciliation Act of 2010, which we collectively refer to as the Health Care Reform Law, requires all individual and certain group health plans to guarantee issuance and renew coverage without pre-existing condition exclusions or health-status rating adjustments. Accordingly, newly issued individual and certain group health plans are not subject to underwriting in 2014 and beyond.underwriting. Further, underwriting techniques are not employed in connection with our Medicare, military services, or Medicaid products because government regulations require us to accept all eligible applicants regardless of their health or prior medical history.

The health benefits industry is highly competitive. Our competitors vary by local market and include other managed care companies, national insurance companies, and other HMOs and PPOs. Many of our competitors have a larger membership base and/or greater financial resources than our health plans in the markets in which we compete. Our ability to sell our products and to retain customers may be influenced by such factors as those described in Item 1A. – Risk Factors in this 20152018 Form 10-K.

Diverse legislative and regulatory initiatives at both the federal and state levels continue to affect aspects of the nation’s health care system.system, including the Health Care Reform Law.

Our management works proactively to ensure compliance with all governmental laws and regulations affecting our business. We are unable to predict how existing federal or state laws and regulations may be changed or interpreted, what additional laws or regulations affecting our businesses may be enacted or proposed, when and which of the proposed laws will be adopted or what effect any such new laws and regulations will have on our results of operations, financial position, or cash flows.

For a description of certain material current activities in the federal and state legislative areas, see Item 1A. – Risk Factors in this 20152018 Form 10-K.

We bear general business risks associated with operating our Company such as professional and general liability, employee workers’ compensation, cybersecurity, and officer and director errors and omissions risks. Professional and general liability risks may include, for example, medical malpractice claims and disputes with members regarding benefit coverage. We retain certain of these risks through our wholly-owned, captive insurance subsidiary. We reduce exposure to these risks by insuring levels of coverage for losses in excess of our retained limits with a number of third-party insurance companies. We remain liable in the event these insurance companies are unable to pay their portion of the losses.

We provide centralized management services to each of our health plans and to our business segments from our headquarters and service centers. These services include management information systems, product development and administration, finance, human resources, accounting, law, public relations, marketing, insurance, purchasing, risk management, internal audit, actuarial, underwriting, claims processing, billing/enrollment, and customer service. Through intercompany service agreements approved, if required, by state regulatory authorities, Humana Inc., our parent company, charges a management fee for reimbursement of certain centralized services provided to its subsidiaries.

As of December 31, 2015,2018, we had approximately 50,10041,600 employees and approximately 1,6002,000 additional medical professionals working under management agreements primarily between us and affiliated physician-owned associations. We believe we have good relations with our employees and have not experienced any work stoppages.

Key to our operational strategy is the implementation of clinical initiatives that we believe provide a better health care experience for our members, lower the cost of healthcare services delivered to our members, and appropriately document the risk profile of our members. Our profitability and competitiveness depend in large part on our ability to

Failure to adequately price our products or estimate sufficient benefits payable or future policy benefits payable or effectively manage our operating expenses, may result in a material adverse effect on our results of operations, financial position, and cash flows.

We are in a highly competitive industry. Some of our competitors are more established in the health care industry in terms of a larger market share and have greater financial resources than we do in some markets. In addition, other companies may enter our markets in the future, including emerging competitors in the Medicare program or competitors in the delivery of health care services. We may also face increased competition due to participation by other insurers in the health insurance exchanges implemented under the Health Care Reform Law. We believe that barriers to entry in our markets are not substantial, so the addition of new competitors can occur relatively easily, and customers enjoy significant flexibility in moving between competitors. Contracts for the sale of commercial products are generally bid upon or renewed annually. While health plans compete on the basis of many factors, including service and the quality and depth of provider networks, we expect that price will continue to be a significant basis of competition. In addition to the challenge of controlling health care costs, we face intense competitive pressure to contain premium prices. Factors such as business consolidations, strategic alliances, legislative reform, and marketing practices create pressure to contain premium price increases, despite being faced with increasing medical costs.

The policies and decisions of the federal and state governments regarding the Medicare, military Medicaid and health insurance exchangeMedicaid programs in which we participate have a substantial impact on our profitability. These governmental policies and decisions, which we cannot predict with certainty, directly shape the premiums or other revenues to us under the programs, the eligibility and enrollment of our members, the services we provide to our members, and our administrative, health care services, and other costs associated with these programs. Legislative or regulatory actions, such as those resulting in a reduction in premium payments to us, an increase in our cost of administrative and health care services, or additional fees, taxes or assessments, may have a material adverse effect on our results of operations, financial position, and cash flows.

Premium increases, introduction of new product designs, and our relationships with our providers in various markets, among other issues, could also affect our membership levels. Other actions that could affect membership levels include our possible exit from or entrance into Medicare or commercial markets, or the termination of a large contract.

If we do not compete effectively in our markets, if we set rates too high or too low in highly competitive markets to keep or increase our market share, if membership does not increase as we expect, if membership declines, or if we lose membership with favorable medical cost experience while retaining or increasing membership with unfavorable medical cost experience, our results of operations, financial position, and cash flows may be materially adversely affected.

Our future performance depends in large part upon our ability to execute our strategy, including opportunities created by the expansion of our Medicare programs, the successful implementation of our integrated care delivery model and our strategy with respect to state-based contracts, including those covering members dually eligible for the Medicare and Medicaid programs, and our participation in health insurance exchanges.programs.

We have made substantial investments in the Medicare program to enhance our ability to participate in these programs. We have increased the size of our Medicare geographic reach through expanded Medicare product offerings. We offer both stand-alone Medicare prescription drug coverage and Medicare Advantage health plans with prescription drug coverage in addition to our other product offerings. We offer a Medicare prescription drug plan in 50 states as well as Puerto Rico and the District of Columbia. The growth of our Medicare products is an important part of our business strategy. Any failure to achieve this growth may have a material adverse effect on our results of operations, financial position, or cash flows. In addition, the expansion of our Medicare products in relation to our other businesses may intensify the risks to us inherent in Medicare products. There is significant concentration of our revenues in Medicare products, with approximately 72%80% of our total premiums and services revenue for the year ended December 31, 20152018 generated from our Medicare products, including 14%15% derived from our individual Medicare Advantage contracts with CMS in Florida. These expansion efforts may result in less diversification of our revenue stream and increased risks associated with operating in a highly regulated industry, as discussed further below.

The recently implemented Health Care Reform Law created a federal Medicare-Medicaid Coordination Office to serve dual eligibles. This Medicare-Medicaid Coordination Office has initiated a series of state demonstration projects to experiment with better coordination of care between Medicare and Medicaid. Depending upon the results of those demonstration projects, CMS may change the way in which dual eligibles are serviced. If we are unable to implement our strategic initiatives to address the dual eligibles opportunity, including our participation in state-based contracts, or if our initiatives are not successful at attracting or retaining dual eligible members, our business may be materially adversely affected.

Our business depends significantly on effective information systems and the integrity and timeliness of the data we use to run our business. Our business strategy involves providing members and providers with easy to use products that leverage our information to meet their needs. Our ability to adequately price our products and services, provide effective and efficient service to our customers, and to timely and accurately report our financial results depends significantly on the integrity of the data in our information systems. As a result of our past and on-going acquisition activities, we have acquired additional information systems. We have reduced the number of systems we operate, have upgraded and expanded our information systems capabilities, and are gradually migrating existing business to fewer systems. Our information systems require an ongoing commitment of significant resources to maintain, protect, and enhance existing systems and develop new systems to keep pace with continuing changes in information processing technology, evolving industry and regulatory standards, and changing customer preferences. If the information we rely upon to run our businesses was found to be inaccurate or unreliable or if we fail to maintain effectively our information systems and data integrity, we could have operational disruptions, have problems in determining medical cost estimates and establishing appropriate pricing, have customer and physician and other health care provider disputes, have regulatory or other legal problems, have increases in operating expenses, lose existing customers, have difficulty in attracting new customers, or suffer other adverse consequences.

We depend on independent third parties for significant portions of our systems-related support, equipment, facilities, and certain data, including data center operations, data network, voice communication services and pharmacy data processing. This dependence makes our operations vulnerable to such third parties' failure to perform adequately under the contract, due to internal or external factors. A change in service providers could result in a decline in service quality and effectiveness or less favorable contract terms which may adversely affect our operating results.

We rely on our agreements with customers, confidentiality agreements with employees, and our trade secrets and copyrights to protect our proprietary rights. These legal protections and precautions may not prevent misappropriation of our proprietary information. In addition, substantial litigation regarding intellectual property rights exists in the

There can be no assurance that our information technology, or IT, process will successfully improve existing systems, develop new systems to support our expanding operations, integrate new systems, protect our proprietary information, defend against cybersecurity attacks, or improve service levels. In addition, there can be no assurance that additional systems issues will not arise in the future. Failure to adequately protect and maintain the integrity of our information systems and data, or to defend against cybersecurity attacks, may result in a material adverse effect on our results of operations, financial position, and cash flows.

In the ordinary course of our business, we process, store and transmit large amounts of data, including sensitive personal information as well as proprietary or confidential information relating to our business or a third-party. We have been, and will likely continue to be, regular targets of attempted cybersecurity attacks and other security threats and may be subject to breaches of our information technology security systems. Although the impact of such attacks has not been material to our operations or results of operations, financial position, or cash flow through December 31, 2018, we can provide no assurance that we will be able to detect, prevent, or contain the effects of such cybersecurity attacks or other information security risks or threats in the future. A cybersecurity attack may penetrate our layered security controls and misappropriate or compromise sensitive personal information or proprietary or confidential information or that of third-parties, create system disruptions, cause shutdowns, or deploy viruses, worms, and other malicious software programs that attack our systems. A cybersecurity attack that bypasses our IT security systems successfully could materially affect us due to the theft, destruction, loss, misappropriation or release of confidential data or intellectual property, operational or business delays resulting from the disruption of our IT systems, or negative publicity resulting in reputation or brand damage with our members, customers, providers, and other stakeholders. In certain circumstances we may rely on third party vendors to process, store and transmit large amounts of data for our businesses whose operations are subject to similar risks.

The costs to eliminate or address cybersecurity threats and vulnerabilities before or after an incident could be substantial. Our remediation efforts may not be successful and could result in interruptions, delays, or cessation of service, and loss of existing or potential members. In addition, breaches of our security measures and the unauthorized dissemination of sensitive personal information or proprietary or confidential information about us or our members or other third-parties, could expose our associates' or members’ private information and result in the risk of financial or medical identity theft, or expose us or other third-parties to a risk of loss or misuse of this information, result in significant regulatory fines or penalties, litigation and potential liability for us, damage our brand and reputation, or otherwise harm our business.

We are or may become a party to a variety of legal actions that affect our business, including breach of contract actions, employment and employment discrimination-related suits, employee benefit claims, stockholder suits and other securities laws claims, and tort claims.

In addition, because of the nature of the health care business, we are subject to a variety of legal actions relating to our business operations, including the design, management, and offering of products and services. These include and could include in the future:

In some cases, substantial non-economic or punitive damages as well as treble damages under the federal False Claims Act, Racketeer Influenced and Corrupt Organizations Act and other statutes may be sought.

While we currently have insurance coverage for some of these potential liabilities, other potential liabilities may not be covered by insurance, insurers may dispute coverage, or the amount of our insurance may not be enough to cover the damages awarded. In addition, some types of damages, like punitive damages, may not be covered by insurance. In some jurisdictions, coverage of punitive damages is prohibited. Insurance coverage for all or some forms of liability may become unavailable or prohibitively expensive in the future.

The health benefits industry continues to receive significant negative publicity reflecting the public perception of the industry. This publicity and perception have been accompanied by increased litigation, including some large jury awards, legislative activity, regulation, and governmental review of industry practices. These factors may materially adversely affect our ability to market our products or services, may require us to change our products or services or otherwise change our business practices, may increase the regulatory burdens under which we operate, and may require us to pay large judgments or fines. Any combination of these factors could further increase our cost of doing business and adversely affect our results of operations, financial position, and cash flows.

See "Legal Proceedings and Certain Regulatory Matters" in Note 16 to the consolidated financial statements included in Item 8. - Financial Statements and Supplementary Data. We cannot predict the outcome of these matters with certainty.

A significant portion of our revenues relates to federal and state government health care coverage programs, including the Medicare, military, and Medicaid programs. These programs accounted for approximately 73%85% of our total premiums and services revenue for the year ended December 31, 2015.2018. These programs involve various risks, as described further below.

The Patient Protection and Affordable Care Act and The Health Care and Education Reconciliation Act of 2010 (which we collectively refer to as the Health Care Reform Law) enacted significant reforms to various aspects of the U.S. health insurance industry. The provisions of the Health Care Reform Law include, among others, imposing a significant new non-deductible health insurance industry fee and other assessments on health insurers, limiting Medicare Advantage payment rates, stipulating a prescribed minimum ratio for the amount of premiums revenue to be expended on medical costs for insured products, additional mandated benefits and guarantee issuance associated with commercial medical insurance, requirements that limit the ability of health plans to vary premiums based on assessments of underlying risk, and heightened scrutiny by state and federal regulators of our business practices, including our Medicare bid and pricing practices. The Health Care Reform Law also specifies benefit design guidelines, limits rating and pricing practices, encourages additional competition (including potential incentives for new market entrants), establishes federally-facilitated or state-based exchanges for individuals and small employers (with up to 100 employees) coupled

These regulations set standards for the security of electronic health information.information, including requirements that insurers provide customers with notice regarding how their non-public personal information is used, including an opportunity to "opt out" of certain disclosures. Violations of these rules could subject us to significant criminal and civil penalties, including significant monetary penalties. Compliance with HIPAA regulations requires significant systems enhancements, training and administrative effort. HIPAA can also expose us to additional liability for violations by our business associates (e.g., entities that provide services to health plans and providers).

The HITECH Act, one part of the American Recovery and Reinvestment Act of 2009, significantly broadened the scope of the privacy and security regulations of HIPAA. Among other requirements, the HITECH Act and HIPAA mandate individual notification in the event of a breach of unsecured, individually identifiable health information, provides enhanced penalties for HIPAA violations, requires business associates to comply with certain provisions of the HIPAA privacy and security rule, and grants enforcement authority to state attorneys general in addition to the HHS Office of Civil Rights.

In addition, there are numerous federal and state laws and regulations addressing patient and consumer privacy concerns, including unauthorized access or theft of personal information. State statutes and regulations vary from state to state and could impose additional penalties. Violations of HIPAA or applicable federal or state laws or regulations could subject us to significant criminal or civil penalties, including significant monetary penalties. Compliance with HIPAA and other privacy regulations requires significant systems enhancements, training and administrative effort.

On February 17, 2009, the American Recovery and Reinvestment Act of 2009, or ARRA, was enacted into law. In addition to including a temporary subsidy for health care continuation coverage issued pursuant to the Consolidated Omnibus Budget Reconciliation Act, or COBRA, ARRA also expands and strengthens the privacy and security provisions of HIPAA and imposes additional limits on the use and disclosure of protected health information, or PHI. Among other things, ARRA requires us and other covered entities to report any unauthorized release or use of or access to PHI to any impacted individuals and to the U.S. Department of Health and Human ServicesHHS in those instances where the unauthorized activity poses a significant risk of financial, reputational or other harm to the individuals, and to notify the media in any states where 500 or more people are impacted by any unauthorized release or use of or access to PHI. ARRA also requires business associates to comply with certain HIPAA provisions. ARRA also establishes higher civil and criminal penalties for covered entities and business associates who fail to comply with HIPAA’s provisions and requires the U.S. Department of Health and Human ServicesHHS to issue regulations implementing its privacy and security enhancements. 

As a corporate entity, Humana Inc. is not licensed to practice medicine. Many states in which we operate through our subsidiaries limit the practice of medicine to licensed individuals or professional organizations comprised of licensed individuals, and business corporations generally may not exercise control over the medical decisions of physicians. Statutes and regulations relating to the practice of medicine, fee-splitting between physicians and referral sources, and similar issues vary widely from state to state. Under management agreements between certain of our subsidiaries and affiliated physician-owned professional groups, these groups retain sole responsibility for all medical decisions, as well as for hiring and managing physicians and other licensed healthcare providers, developing operating policies and procedures, implementing professional standards and controls, and maintaining malpractice insurance. We believe that our health services operations comply with applicable state statutes regarding corporate practice of medicine, fee-splitting,fee-

A federal law commonly referred to as the “Anti-Kickback Statute” prohibits the offer, payment, solicitation, or receipt of any form of remuneration to induce, or in return for, the referral of Medicare or other governmental health program patients or patient care opportunities, or in return for the purchase, lease, or order of items or services that are covered by Medicare or other federal governmental health programs. Because the prohibitions contained in the Anti-Kickback Statute apply to the furnishing of items or services for which payment is made in “whole or in part,” the Anti-Kickback Statute could be implicated if any portion of an item or service we provide is covered by any of the state or federal health benefit programs described above. Violation of these provisions constitutes a felony criminal offense and applicable sanctions could include exclusion from the Medicare and Medicaid programs.

Many states also have enacted laws similar in scope and purpose to the Anti-Kickback Statute and, in more limited instances, the Stark Law, that are not limited to services for which Medicare or Medicaid payment is made. In addition, most states have statutes, regulations, or professional codes that restrict a physician from accepting various kinds of remuneration in exchange for making referrals. These laws vary from state to state and have seldom been interpreted by the courts or regulatory agencies. In states that have enacted these statutes, we believe that regulatory authorities and state courts interpreting these statutes may regard federal law under the Anti-Kickback Statute and the Stark Law as persuasive.

We believe that our operations comply with the Anti-Kickback Statute, the Stark Law, and similar federal or state laws addressing fraud and abuse. These laws are subject to modification and changes in interpretation, and are enforced by authorities vested with broad discretion. We continually monitor developments in this area. If these laws are interpreted in a manner contrary to our interpretation or are reinterpreted or amended, or if new legislation is enacted with respect to healthcare fraud and abuse, illegal remuneration, or similar issues, we may be required to restructure our affected operations to maintain compliance with applicable law. There can be no assurances that any such restructuring will be possible or, if possible, would not have a material adverse effect on our results of operations, financial position, or cash flows.

We are subject to various federal, state, and local laws and regulations relating to the protection of human health and the environment. If an environmental regulatory agency finds any of our facilities to be in violation of environmental laws, penalties and fines may be imposed for each day of violation and the affected facility could be forced to cease operations. We could also incur other significant costs, such as cleanup costs or claims by third parties, as a result of violations of, or liabilities under, environmental laws. Although we believe that our environmental practices, including waste handling and disposal practices, are in material compliance with applicable laws, future claims or violations, or changes in environmental laws, could have a material adverse effect on our results of operations, financial position or cash flows.

Our common stock trades on the New York Stock Exchange under the symbol HUM. The following table shows the range of high and low closing sales prices as reported on the New York Stock Exchange Composite Price for each quarter in the years ended December 31, 2015 and 2014:

As of January 31, 2016,2019, there were approximately 2,9002,300 holders of record of our common stock and approximately 41,200244,700 beneficial holders of our common stock.

The following table provides details of dividend payments, excluding dividend equivalent rights, in 20142017 and 2015,2018, under our Board approved quarterly cash dividend policy:

The following graph compares our total return to stockholders with the returns of the Standard & Poor’s Composite 500 Index (“S&P 500”) and the Dow Jones US Select Health Care Providers Index (“Peer Group”) for the five years ended December 31, 2015.2018. The graph assumes an investment of $100 in each of our common stock, the S&P 500, and the Peer Group on December 31, 2010,2013, and that dividends were reinvested when paid.