Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934 (Amendment No. )


United Therapeutics Corporation
(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)
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The 2018 annual meeting of shareholders of United Therapeutics Corporation will be held at our co-headquarters located at 1110 Spring Street, Silver Spring, Maryland 20910, on Tuesday, June 26, 2018, at 9:30 a.m. local time for the following purposes:

Only shareholders as of April 30, 2018 are entitled to notice of, and to vote at, our 2018 annual meeting of shareholders.

Important Notice Regarding the Availability of Proxy Materials for United Therapeutics Corporation's 2018 Annual Meeting of Shareholders to Be Held on Tuesday, June 26, 2018:

United Therapeutics Corporation's Proxy Statement and Annual Report on Form 10-K are available at:
http://ir.unither.com/annual-and-proxy.

WHETHER OR NOT YOU EXPECT TO ATTEND THE MEETING, YOU ARE REQUESTED TO VOTE YOUR SHARES AS PROMPTLY AS POSSIBLE SO THAT YOUR SHARES ARE REPRESENTED AT THE MEETING. ALL SHAREHOLDERS ARE EXTENDED A CORDIAL INVITATION TO ATTEND THIS MEETING. If you wish to attend the meeting in person, you will be asked to present your admission ticket and valid, government-issued photo identification, such as a driver's license, as described in the Proxy Statement.

Please refer to page 24 of the Proxy Statement for a letter from the Chairman of our Compensation Committee of our Board of Directors.

This Proxy Statement and the accompanying proxy card are being furnished to shareholders of United Therapeutics Corporation in connection with the solicitation by our Board of Directors (Board) of proxies to be voted at our 2018 annual meeting of shareholders (Annual Meeting) and any adjournment or postponement thereof. Our Annual Meeting will be held on Tuesday, June 26, 2018, beginning at 9:30 a.m. local time at our co-headquarters located at 1110 Spring Street, Silver Spring, Maryland 20910. Proxy materials or a Notice of Internet Availability of Proxy Materials (Notice) were first sent to shareholders on or about May 7, 2018.

On April 30, 2018 (the Record Date), there were approximately 43,544,022 shares of our common stock outstanding and entitled to vote at our Annual Meeting. Only shareholders of record on the Record Date will be entitled to vote, either in person or by proxy, at our Annual Meeting, and each share will have one vote for each director nominee and one vote for each other matter to be voted on. If you are a beneficial owner of shares of our common stock (that is, you hold shares through a broker, bank, trust or other nominee), you must obtain a legal proxy from the broker, bank, trust or other nominee that holds your shares if you wish to vote in person at the meeting.

As permitted by the rules of the Securities and Exchange Commission, we are making our proxy materials available to shareholders primarily via the Internet, rather than mailing printed copies of these materials to shareholders. On or about May 1, 2018, we sent to many of our shareholders a Notice containing instructions on how to access and review our proxy materials, including our Proxy Statement and the 2018 Annual Report on Form 10-K, and vote online.

This process is designed to expedite shareholders' receipt of proxy materials, lower the cost of the annual meeting, and help conserve natural resources. If you received a Notice by mail, you will not receive a printed copy of the proxy materials unless you request one. If you would prefer to receive printed proxy materials, please follow the instructions included in the Notice. Shareholders who requested paper copies of the proxy materials did not receive the Notice and will receive the proxy materials in the format requested.

We will bear the cost of soliciting proxies. Our directors, officers and employees may solicit proxies in person or by telephone, fax, email or regular mail, and they will receive no additional compensation for such work. Copies of solicitation materials may be furnished to brokers, custodians, nominees and other fiduciaries for forwarding to beneficial owners of shares of our common stock, and normal handling charges may be paid for such forwarding service. We have also retained Georgeson Inc. to assist in soliciting proxies for a fee of approximately $12,000 plus customary expenses.

Shares can be voted at our Annual Meeting only by shareholders who are present in person or represented by proxy. Whether or not you plan to attend our Annual Meeting in person, you are encouraged to vote your shares. The representation in person or by proxy of at least a majority of the outstanding shares entitled to vote is necessary to achieve a quorum for the transaction of business at the Annual Meeting.

If you are a shareholder of record (that is, you hold shares in your own name), you may revoke any proxy given pursuant to this solicitation at any time before it is exercised by delivering to the Corporate Secretary of United Therapeutics Corporation at 1040 Spring Street, Silver Spring, Maryland 20910 a written notice of revocation or a fully executed proxy bearing a later date, or by attending the Annual Meeting and voting in person. If you are a beneficial owner (that is, you hold shares through a broker, bank, trust or other nominee), please contact your bank or broker to revoke a previously given proxy or change your voting instructions.

If you are a beneficial owner, your broker, bank, trust or other nominee has the discretion to vote on routine corporate matters presented in the proxy materials without your specific voting instructions. Your broker, bank, trust or other nominee does not have the discretion to vote on non-routine matters. Only Proposal No. 4 (ratification of the appointment of our independent registered public accounting firm) is considered a routine matter. Proposals No. 1, 2 and 3 are not considered routine matters, and without your specific voting instructions your shares will not be voted on these proposals.

Abstentions and "broker non-votes" (i.e., shares held by brokers, banks, trusts or other nominees that are represented at the meeting but with respect to which they have no discretionary power to vote on a particular matter and have received no instructions from the beneficial owners thereof) will be counted as present in determining whether the quorum requirement is satisfied.

If the enclosed proxy card is properly executed and returned prior to the Annual Meeting, the shares represented by the proxy card will be voted in accordance with the shareholder's directions. If the proxy card is signed and returned without any direction given, shares of our common stock represented by the proxy will be voted in accordance with our Board's recommendations as follows: (i) FOR the election of each of the four director nominees named on the proxy card; (ii) FOR the advisory resolution to approve executive compensation; (iii) FOR the approval of the amendment and restatement of the United Therapeutics Corporation 2015 Stock Incentive Plan; and (iv) FOR the ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm for 2018.

Directors are elected by a majority of votes cast at our Annual Meeting. A majority of votes cast means that the number of votes cast for the director nominee's election must exceed the number of votes cast against that director nominee's election. Broker non-votes and abstentions are not considered votes cast and therefore have no impact on the election of directors. Cumulative voting is not permitted in the election of directors. Proxies may not be voted for more than four nominees.

The affirmative vote of the holders of a majority of the outstanding shares of common stock present, in person or by proxy, at our Annual Meeting, and entitled to vote on the matter, is required for approval of each of the other proposals to be voted on at the meeting. Abstentions have the same effect as an "against" vote. Broker non-votes, if any, have no impact on the vote.

Our Board consists of ten members and is divided into three classes of three or four members each. At each annual meeting of shareholders, members of one of the classes, on a rotating basis, are elected to a three-year term. This year at our Annual Meeting, Professor Katherine Klein, Mr. Ray Kurzweil, Dr. Martine Rothblatt and Dr. Louis Sullivan are nominees for election as Class I directors to serve three-year terms until our 2021 annual meeting of shareholders or until their successors are duly elected and qualified or their office is otherwise vacated.

Each of our director nominees has consented to be named herein and to continue to serve on our Board of Directors, if elected. We do not anticipate that any nominee will become unable or unwilling to accept his or her nomination or election. If such an event should occur, the persons named on the proxy card intend to vote for the election of such other person as is recommended to our Board by our Nominating and Governance Committee in such nominee's stead. In the alternative, the persons named on the proxy card may simply vote for the remaining nominees, leaving a vacancy that may be filled at a later date by our Board of Directors, or our Board of Directors may reduce the size of our Board.

We believe that our directors should possess the highest personal and professional ethics, integrity and values, and be committed to representing the best interests of our shareholders. We also endeavor to have a Board of Directors that, as a whole, represents a range of experiences in business, government, education and technology and in other areas that are relevant to our business activities. In addition, our Board believes there are certain attributes every director should possess, which are described in the Director Nominations and Diversity section below.

In evaluating incumbent directors for re-nomination to our Board, the members of our Nominating and Governance Committee consider a variety of factors. These include each director's independence, financial literacy, personal and professional accomplishments, tenure on our Board and experience in light of our business goals. The following presents information concerning persons nominated for election as directors at our Annual Meeting and for those of our directors whose terms of office will continue after our Annual Meeting, including their age (as of the date of this Proxy Statement), membership on committees of our Board, principal occupations or affiliations during the last five years or more, director qualifications, and certain other directorships held. For additional information concerning the director nominees, including stock ownership and compensation, see the section entitled Non-Employee Director Compensation and the Beneficial Ownership of Common Stock table below.

Nominees as Class I Directors for Election at our 2018 Annual Meeting of Shareholders


Katherine Klein, Ph.D. Age 61		Professor Klein has served as the Vice-Dean of the Wharton Social Impact Initiative since July 2012, and as The Wharton School's Edward H. Bowman Professor of Management since 2005. She also served as Professor of Management of The Wharton School from 2004 to 2005. Prior to joining Wharton, Professor Klein was on the faculty of the University of Maryland and a visiting professor at the Stanford Graduate School of Business. She received her B.A. from Yale University, and her Ph.D. in Community Psychology from the University of Texas at Austin. An award-winning organizational psychologist, Professor Klein has conducted extensive field research regarding a range of topics including team leadership, climate, conflict, social networks and effectiveness; organizational change and technology implementation; employee diversity; and employee responses to stock ownership. She has taught executive education and consulted with and studied a variety of for-profit and non-profit organizations including Charles Schwab, Rohm and Haas, North American Scientific, Medtronic, The Baltimore Shock Trauma Center, Penn Vet, the U.S. Census Bureau, and the Korean Management Association. Her research has been published in numerous top journals including Administrative Science Quarterly, Journal of Applied Psychology, the Academy of Management Journal, and the Academy of Management Review. She is also a former associate editor of the Journal of Applied Psychology and Administrative Science Quarterly. Professor Klein is a Fellow of the Academy of Management, the Society for Industrial and Organizational Psychology, the American Psychological Association, and the Association for Psychological Science. She has served as a United Therapeutics director since 2014.
		As a professor and Vice-Dean at one of the world's leading business schools, Professor Klein brings valuable expertise in organizational behavior and employee ownership culture, two topics that are of vital importance to a growing biotech company like United Therapeutics. As we adapt to the needs of a more mature company while balancing our goal of maintaining an entrepreneurial culture designed to foster continued high growth and innovation, Professor Klein provides valuable insight to our Board.


Ray Kurzweil Age 70		Mr. Kurzweil is an inventor, entrepreneur and author, and has created several important technologies in the artificial intelligence field. He has received the National Medal of Technology, the MIT Lemelson Prize, twenty-one honorary doctorates, a Grammy award for his contributions to music technology, and honors from three U.S. Presidents. In 2002, Mr. Kurzweil was inducted into the National Inventors Hall of Fame. Since 1995, Mr. Kurzweil has served as the Chief Executive Officer of Kurzweil Technologies, Inc., a technology development firm. Since January 2013, he has also served as a Director of Engineering for Google Inc., a global technology and Internet search company. He has served as a United Therapeutics director since 2002.
		Mr. Kurzweil brings to our Board extensive technological experience as an inventor and technology developer. His technical experience in the areas of artificial intelligence, telemedicine, and pharmaceutical research and development, and his experience in building businesses around his inventions, provide our Board with perspective in evaluating current and proposed technologies and business opportunities. Mr. Kurzweil also brings to our Board substantial corporate leadership experience from his role as Chief Executive Officer of Kurzweil Technologies, Inc.
Martine Rothblatt, Ph.D., J.D., M.B.A. Age 63 *Chairman of the Board* *Chief Executive Officer*		Dr. Rothblatt founded United Therapeutics in 1996 and served as Chairman and Chief Executive Officer since its inception through January 2015, when she became our Chairman and Co-Chief Executive Officer. She was promoted to her current role as Chairman and soul CEO in June 2016. Prior to founding United Therapeutics, she founded and served as Chairman and Chief Executive Officer of Sirius XM Satellite Radio. She is a co-inventor on six of our patents pertaining to treprostinil. In 2014, Dr. Rothblatt was appointed to the Committee of Science, Technology and Law of the National Research Council. She has served as a United Therapeutics director since 1996.
		Dr. Rothblatt brings to our Board extensive leadership and business experience at technology companies, as well as in-depth knowledge of our company from her service as our founder, Chairman and Chief Executive Officer. She also has substantial knowledge of medical ethics, having obtained her Ph.D. in medical ethics from the University of London.


Louis Sullivan, M.D. Age 84 **Member, Compensation Committee Member, Nominating and Governance Committee**		Dr. Sullivan was the founding President of Morehouse School of Medicine, from 1981 to 1989, served as President again from 1993 to 2002, and became President Emeritus in 2002. Dr. Sullivan was also one of the founders and served as Chairman of Medical Education for South African Blacks, Inc., a member of the National Executive Council for the Boy Scouts of America, and a member of the Board of Trustees of Little League of America. Dr. Sullivan served as Secretary of the U.S. Department of Health and Human Services from 1989 to 1993. He is a physician certified in internal medicine with a subspecialty certification in hematology. Dr. Sullivan currently serves on the board of directors of Emergent BioSolutions, Inc. (since 2005), a publicly-traded company. He also serves as Co-Chair of the Henry Schein Cares Foundation. Dr. Sullivan previously served on the boards of directors of a wide range of public companies, including General Motors Company, BioSante Pharmaceuticals, Inc., Bristol-Myers Squibb Company, Cigna Corporation, 3M Company, Henry Schein, Inc., Household International (now HSBC), Equifax and Georgia Pacific Corporation. He has served as a United Therapeutics director since 2002.
		Dr. Sullivan brings to our Board extensive experience in the healthcare industry as a public official from his service as a Secretary of the U.S. Department of Health and Human Services, physician certified in internal medicine and professor and administrator at Morehouse School of Medicine. He also has substantial public company board experience gained from his service as a director of Henry Schein, Inc. and Emergent BioSolutions, Inc. as well as his previous public company board service.


Christopher Causey, M.B.A. Age 55 *Chairman,* Compensation Committee *Member,* Nominating and Governance Committee		Mr. Causey has served as the Principal of the Causey Consortium, a professional services organization providing business strategy and marketing counsel to the healthcare industry, since 2002. Previously, Mr. Causey served as a senior marketing officer for a variety of healthcare companies. From 2001 to 2002, Mr. Causey served as the Chief Marketing Officer for Definity Health Incorporated. He was also a member of the board of directors of Data Sciences International, Inc., a private company that develops wireless physiological monitoring solutions, from 2008 to 2013. Mr. Causey has served as a United Therapeutics director since 2003.
		Drawing upon over 20 years of experience in strategic planning and marketing for health care delivery, financing and biotechnology organizations, including as Principal of Causey Consortium, Mr. Causey brings to our Board substantial experience in the health care and biotech industries. Our Board benefits from Mr. Causey's extensive leadership experience as a senior health care marketing executive.
Richard Giltner Age 54 *Chairman,* Audit Committee **Member, Nominating and Governance Committee**		From 2009 until his retirement in 2010, Mr. Giltner was a portfolio manager at Lyxor Asset Management, an asset management group at the French bank Société Générale. From 2006 until 2009, he served as a managing director of Société Générale Asset Management, an international fund management firm, and head of the European office for its fund of hedge funds group. From 2003 to 2006, Mr. Giltner was the global head of foreign exchange options for the investment banking arm of Société Générale. He also held various other managerial positions within Société Générale from 1991 until 2003. Mr. Giltner has been a private investor since his retirement from Société Générale in 2010. Our Board of Directors has determined that Mr. Giltner is an audit committee financial expert as defined under the rules and regulations of the Securities and Exchange Commission (SEC) and meets the financial sophistication requirements of Nasdaq's listing standards. Mr. Giltner has served as a United Therapeutics director since 2009.
		Mr. Giltner brings to our Board over twenty years of experience in the financial sector, including international financial markets, financial derivatives, alternative investments and asset management. As our business continues to grow and expand, our Board benefits from Mr. Giltner's global business and financial experience and his perspective as an institutional investor as well as his leadership experience in international finance from his service in various management roles at Société Générale.


Judy Olian, Ph.D. Age 66 **Member, Compensation Committee**		Dean Olian is the dean of the UCLA Anderson School of Management and the John E. Anderson Chair in Management. Her research and business expertise centers on aligning organizational strategies and design with human resource systems and incentives, and managing top management teams. She began her UCLA appointment in 2006 after serving as dean and professor of management at the Smeal College of Business Administration at the Pennsylvania State University. Earlier, she served in various faculty and executive roles at the University of Maryland and its Robert H. Smith School of Business. Dean Olian serves or has been a member of various advisory boards (including the U.S. Studies Centre at the University of Sydney, Peking University Business School's International Advisory Board and Catalyst, a leading global think tank for women in business), and is Chairman of the Loeb Awards for Business Journalism. Born and raised in Australia, Dean Olian received her B.S. in Psychology from the Hebrew University, Jerusalem and her M.S. and Ph.D. in Industrial Relations from the University of Wisconsin, Madison. She was the Chairman of AACSB International, the premier thought leadership and accreditation organization for leading global business schools, and also serves on the board of directors of Ares Management, L.P., a publicly-traded global alternative asset management firm, and UCLA Technology Development Corporation, a not-for-profit organization focused on protecting and optimizing the discoveries and inventions developed at UCLA. She has served as a United Therapeutics director since 2015.
		As the dean of one of the world's leading business schools, Dean Olian brings valuable expertise in managing and leading a large organization. Her academic expertise, which centers on the alignment of organizational strategies with human resource systems and incentives, provides valuable insight to a growing biotech company like United Therapeutics. In addition, her experience as a director of Ares Management provides valuable public company board experience.


Raymond Dwek, C.B.E., F.R.S. Age 76		Professor Dwek is a Fellow of the Royal Society, London, and has served as Director of the Glycobiology Institute at the University of Oxford since 1988. He also served as Professor of Glycobiology at the University of Oxford from 1988 through 2009, and currently serves as Professor Emeritus. He was President of the Institute of Biology (a professional organization) from 2008 through 2010. From 2000 to 2006, Professor Dwek served as head of the Department of Biochemistry at the University of Oxford. Professor Dwek has been serving in various positions at the University of Oxford since 1966. In 1988, Professor Dwek was the scientific founder of Oxford GlycoSciences PLC, which was publicly traded on the London Stock Exchange and Nasdaq, and he served as a member of its Board of Directors until its sale in 2003. He was the 2007 Kluge Chair of Technology and Society at the U.S. Library of Congress. Professor Dwek is the founder of glycobiology, the study of the structure, biosynthesis and biology of sugar chains attached to proteins. He has served as a United Therapeutics director since 2002.
		Professor Dwek has extensive scientific experience as both head of the Department of Biochemistry at the University of Oxford, one of the world's largest biochemistry departments, and as a biotechnology innovator at organizations such as the Glycobiology Institute and Oxford GlycoSciences PLC. In evaluating existing and potential new programs, our Board benefits from his scientific insight and experience in pharmaceutical research and development.


Christopher Patusky, J.D., M.G.A. Age 54 *Vice Chairman of the Board* *Lead Independent Director* **Chairman, Nominating and Governance Committee Member, Audit Committee Member, Compensation Committee**		Mr. Patusky has more than 25 years of experience in the private, public and nonprofit sectors. After graduating from The Harvard Law School, he clerked and practiced law from 1988 to 2000, focusing on litigation, intellectual property, and business startups. After receiving a master's degree in governmental administration from the University of Pennsylvania, Mr. Patusky served from 2002 to 2007 as the Executive Director and member of the faculty of the University of Pennsylvania's Fels Institute of Government. From 2007 to 2011, he served as the Director of the Office of Real Estate and member of the Senior Policy Team at the Maryland Department of Transportation, staying on in a part-time capacity until 2013. Since 2012, Mr. Patusky has served as the founding principal of Patusky Associates, LLC, which serves as a personal investment and consulting vehicle, and as an executive manager of Slater Run Vineyards, LLC, his family's farm-based vineyard and winery. Our Board of Directors has determined that Mr. Patusky meets the financial sophistication requirements of Nasdaq's listing standards. He has served as a United Therapeutics director since 2002.
		Mr. Patusky brings to our Board extensive legal and business experience from his law career, and governance experience from his former position as an administrator and faculty member at the Fels Institute of Government. Mr. Patusky also brings to our Board familiarity with governmental regulation and relations between the government and the private sector due to his leadership experience in state government in the Maryland Department of Transportation. His responsibilities at the Fels Institute and the Maryland Department of Transportation included significant budgetary management and oversight responsibilities.


Tommy Thompson, J.D. Age 76 **Member, Audit Committee**		Before entering the private sector in 2005, Governor Thompson enjoyed a long and distinguished career in public service. As Secretary of the U.S. Department of Health and Human Services from 2001 to 2005, he was a leading advocate for the health and welfare of all Americans. He also served four terms as Governor of Wisconsin from 1987 to 2001. Governor Thompson served as a partner at the law firm of Akin Gump Strauss Hauer & Feld LLP in Washington, D.C. from 2005 until January 2012. Governor Thompson has served as Chairman and Chief Executive Officer of Thompson Holdings, a consulting firm, since 2012. In 2017, Governor Thompson became an Adjunct Senior Advisor to Akin Gump. From 2005 to 2009, he also served as the Independent Chairman of the Deloitte Center for Health Solutions, which researches and develops solutions to some of our nation's most pressing health care and public health related challenges. He also served as chairman of the board of directors of AGA Medical Holdings, Inc. from 2005 until 2010, and is a member of the boards of directors of Centene Corporation, Physicians Realty Trust, Tyme Technologies, Inc. and TherapeuticsMD, Inc. He previously served on the boards of numerous other public companies, including Cancer Genetics Inc., CareView Communications, Inc., CNS Response, Inc., C.R. Bard, Inc., Cytori Therapeutics, Inc., SpectraScience and X Shares Advisors. Our Board has determined that Governor Thompson meets the financial sophistication requirements of Nasdaq's listing standards. Governor Thompson has served as a United Therapeutics director since 2010.
		Governor Thompson brings to our Board experience in the healthcare industry, both as a public official (former Secretary of the U.S. Department of Health and Human Services) and in the private sector (Deloitte Center for Health Solutions), as well as public company board experience (AGA Medical Holdings, Inc., CareView Communications, Inc., Centene Corporation, C.R. Bard, Inc., Cytori Therapeutics, Inc., SpectraScience, CNS Response, Inc., Physicians Realty Trust, TherapeuticsMD, Inc., Tyme Technologies, Inc. and X Shares Advisors) and knowledge of legislative affairs. Governor Thompson's legal experience from his private practice at Akin Gump Strauss Hauer & Feld LLP also is useful in our Board's oversight of our legal and regulatory compliance.

Our Board is responsible for overseeing the risks facing our company. Our Board works directly with our executive officers and other members of our senior management team in carrying out its risk oversight function. Our directors take a proactive, interested and detailed approach to their service on our Board and set expectations to promote our success through the achievement of business objectives while maintaining high standards of responsibility and ethics. At its regularly scheduled meetings, our Board receives reports from our Chairman and Chief Executive Officer, President and Chief Operating Officer, Chief Financial Officer and General Counsel, and may also receive reports from the Committee Chairmen, outside consultants and other members of senior management, among others. These presentations often include identification and assessment of risks our company currently faces or may face in the future. Our Board is able to ask questions, discuss and provide guidance to management on the risks presented, as well as any risks that our Board identifies. Our senior management team is responsible for assessing risk on a daily basis. Our Board expects that our senior management team continually identifies, assesses and manages the short-term and long-term risks faced by our company. If members of our senior management team identify risks that are material to our company, our Board may convene a special meeting to discuss, assess and address such risks.

Our Board implements its risk oversight function both as a whole and through delegation to various committees. These committees meet regularly and report back to the full Board. Our Audit Committee's responsibilities include general oversight of our company's practices with respect to financial risk assessment and management. Our Compensation Committee's duties include overseeing an assessment of the incentives and risks arising from or related to our compensation policies and practices, including but not limited to those applicable to our executive officers, and evaluating whether those incentives and risks are appropriate. Our Nominating and Governance Committee's responsibilities include oversight of our company's practices with respect to legal and regulatory compliance risk.

In April 2018, our Compensation Committee reviewed a risk assessment conducted by management and our Compensation Committee's independent compensation consultant, Radford, an Aon Hewitt company (Radford), to determine whether the design of our employee compensation programs and the amounts and components of employee compensation might create incentives for excessive risk-taking by our employees. Based on this review, our Compensation Committee concluded that the risks arising from our employee compensation programs are not reasonably likely to have a material adverse effect on our company. Our Compensation Committee believes that our compensation programs encourage employees, including our executives, to remain focused on a balance of the short-term and long-term operational and financial goals of our company, thereby reducing the potential for actions that involve an excessive level of risk. See the section entitled Compensation Discussion and Analysis—Key Governance Features of Our Executive Compensation Program for information regarding certain risk-mitigating features of our compensation programs.

Dr. Rothblatt, who founded our company, presently serves as Chairman of our Board and Chief Executive Officer. Our Board believes that the combined role of Chairman and Chief Executive Officer is an appropriate leadership structure for our company. In this regard, having a combined Chairman and Chief Executive Officer provides an efficient and effective leadership model for a growing entrepreneurial company like ours, as it fosters clear accountability, effective decision-making, and alignment on corporate strategy. In addition, because our Board works closely with our executive officers and members of senior management, there is a natural synergy in the combined Chairman and Chief Executive Officer role that facilitates our Board's guidance of management.

The independent directors on our Board have designated Mr. Patusky as Lead Independent Director. The Lead Independent Director is selected annually by the independent directors. Among other responsibilities, our Lead Independent Director coordinates the activities of our independent directors, approves Board meeting schedules and agendas, chairs all meetings of our Board when the Chairman is not present, including executive sessions of our independent directors, and serves as principal liaison between our independent directors and our Chairman and senior management. The Lead Independent Director also has the authority to call executive sessions of the independent directors and is available for consultation and communication with major shareholders. A more detailed description of the responsibilities of the Lead Independent Director is included in our Corporate Governance Guidelines, which are available on our website at http://ir.unither.com/corporate-governance.

The Nominating and Governance Committee of our Board does not have a formal policy with respect to considering director candidates or director diversity. Once our Nominating and Governance Committee identifies a potential director nominee, it screens the candidate, performs reference checks and conducts interviews with the assistance of our General Counsel. If the outcome of that process is favorable, our Nominating and Governance Committee may recommend the candidate to our Board for consideration.

Our Nominating and Governance Committee considers candidates recommended by shareholders and evaluates them using the same criteria as it uses to evaluate all other candidates. Our Nominating and Governance Committee seeks to recommend director candidates who will enhance the quality of our Board's deliberations and decisions, who will take their duties seriously and who will promote the values and ethics to which we subscribe.

A shareholder who wishes to recommend a prospective nominee for our Nominating and Governance Committee's consideration should submit the candidate's name and qualifications to our Corporate Secretary at the address set forth under Shareholder Communication with Directors below.

To be considered by our Nominating and Governance Committee, a director candidate must meet the following minimum criteria:

In addition, our Nominating and Governance Committee is interested in candidates who possess the following skills:

Our Nominating and Governance Committee's evaluation of director nominees considers their ability to contribute these qualities and skills to our Board, and our Nominating and Governance Committee reviews its effectiveness in balancing these considerations when assessing the composition of our Board.

Our Board has determined that: (i) Christopher Causey, Richard Giltner, Katherine Klein, Ray Kurzweil, Judy Olian, Christopher Patusky, Louis Sullivan and Tommy Thompson are independent in accordance with the Nasdaq listing standards; (ii) Martine Rothblatt is not independent due her employment as our Chief Executive Officer; (iii) as described below, in an abundance of caution, Raymond Dwek has been designated as not independent due to certain historical transactions between our company and the University of Oxford described in the section entitled Certain Relationships and Related Party Transactions below; (iv) Richard Giltner, Christopher Patusky and Tommy Thompson meet the heightened independence standards for audit committee members set forth in rules promulgated under the Securities Exchange Act of 1934, as amended (the Exchange Act); and (v) Christopher Causey, Judy Olian, Christopher Patusky and Louis Sullivan meet the heightened independence standards for compensation committee members under the Nasdaq listing standards.

Prior to 2011, Professor Dwek was regarded as one of our independent directors. In 2011, our Board determined not to designate Professor Dwek as an independent director under the Nasdaq listing standards, after considering our relationship with the University of Oxford. Our Board believes that Professor Dwek brings significant and valuable independent insight to our Board and does not believe that our relationship with Oxford University falls within any of the categorical prohibitions against a finding of independence under the Nasdaq listing standards. However, in an abundance of caution and in light of our historical relationship with Oxford, our Board currently does not designate Professor Dwek as an "independent director" within the meaning of the Nasdaq listing standards.

Our Board has three standing committees: the Audit Committee, the Compensation Committee and the Nominating and Governance Committee. A summary of each committee's duties can be found below, and additional detail can be found in each committee's charter. The current composition of each committee is as follows:




	Audit	Compensation	Nominating and Governance

Christopher Causey		Chair	Member

Raymond Dwek⁽¹⁾

Richard Giltner	Chair		Member

Katherine Klein

Ray Kurzweil

Judy Olian		Member

Christopher Patusky⁽²⁾	Member	Member	Chair

Martine Rothblatt⁽³⁾

Louis Sullivan		Member	Member

Tommy Thompson	Member

For additional information regarding the processes and procedures used by our Audit Committee, see the section entitled Report of our Audit Committee and Information on our Independent Auditors below.

Our Compensation Committee oversees our compensation plans and policies, reviews and approves compensation for our executive officers, oversees the administration of our equity incentive and share tracking awards plans, reviews and approves grants of stock options and share tracking awards to our executive officers and the methodology and formulae for granting stock options and share tracking awards to other employees. Our Compensation Committee's responsibilities include:

Our Compensation Committee's charter provides that it may delegate responsibilities to subcommittees if it determines such a delegation would be in the best interest of our company. For additional information regarding the processes and procedures used by our Compensation Committee, see the section entitled Compensation Discussion and Analysis below.

Our Compensation Committee has the authority to engage advisors to assist it in carrying out its responsibilities. In accordance with this authority, our Compensation Committee directly engaged Radford, an Aon Hewitt company, as its compensation consultant during 2017 to provide advice to our Compensation Committee on our executive and non-employee director compensation practices and policies. Our Compensation Committee, in its discretion, may replace its independent compensation consultant or hire additional consultants at any time. Radford performed additional services during 2017, namely consulting services for non-executive employee compensation matters and broad-based compensation survey data, and was paid fees for these services totaling approximately $26,200. In addition, Radford affiliates (Aon Hewitt and its related entities) performed actuarial services relating to our SERP, insurance advisory services, stock plan administration and retirement plan advisory services, along with risk management consulting and insurance brokerage services for United Therapeutics during 2017, for which we paid approximately $556,915 during 2017. Additional insurance premiums and related fees were paid to Aon Hewitt and passed through to insurance companies not affiliated with Aon Hewitt. Our Compensation Committee was advised of the nature and extent of these services, which were sought by management, and did not find that they impaired Radford's independence. Since most of these services commenced prior to Radford's appointment as our Compensation Committee's independent consultant, they were not approved by our Compensation Committee or Board of Directors. Our Compensation Committee considered the independence of Radford in light of SEC rules regarding conflicts of interest involving compensation consultants and Nasdaq listing standards regarding compensation consultant independence. Based on its review, our Compensation Committee determined that Radford was independent, and that Radford's work did not raise any conflicts of interest. In making the foregoing determination, our Compensation Committee considered the following six factors, as well as other factors it deemed relevant: (i) the provision of other services to us by Radford; (ii) the amount of fees Radford received from us, as a percentage of their total revenue; (iii) the policies and procedures of Radford that are designed to prevent conflicts of interest; (iv) the lack of any business or personal relationships of the Radford consultants with any member of our Compensation Committee; (v) the lack of any United Therapeutics stock owned by the Radford consultants performing services for our Compensation Committee; and (vi) the lack of any business or personal relationships of the Radford consultants or Radford itself with any of our executive officers.

Our Compensation Committee engaged Radford during 2017 to review and advise our Compensation Committee on all principal aspects of executive and non-employee director

compensation. This included base salaries, cash incentive awards and long-term incentive awards for our executive officers, as well as cash compensation and long-term incentive awards for non-employee directors. Radford performed the following tasks for our Compensation Committee in 2017, among others:

In the course of fulfilling these responsibilities, Radford regularly communicated with our Compensation Committee Chairman outside of and prior to most Compensation Committee meetings. Our Compensation Committee regularly invites its independent compensation consultant to attend its meetings. In 2017, Radford representatives attended each of our Compensation Committee's seven meetings.

While our Compensation Committee considered its independent consultant's recommendations in 2017, our Compensation Committee's decisions, including the specific amounts paid to our executive officers and directors, were its own and may reflect factors and considerations in addition to the information and recommendations provided by its independent consultant.

In addition to the responsibilities described in the section entitled Director Nominations and Diversity above, our Nominating and Governance Committee's responsibilities include:

Upon the recommendation of our Nominating and Governance Committee, our Board has adopted Corporate Governance Guidelines as a framework for the governance of our company. Our Corporate Governance Guidelines, along with the charter for each Board committee, are available electronically in the "Corporate Governance" section of the "Investors" page of our website, located at http://ir.unither.com/corporate-governance, or by writing to us at United Therapeutics Corporation, Attention: Corporate Secretary, 1040 Spring Street, Silver Spring, Maryland 20910, or by sending an e-mail to corporatesecretary@unither.com.

In 2011, our Board adopted Stock Ownership Guidelines applicable to our directors and Named Executive Officers (as defined below) in order to further align the financial interests of our directors and Named Executive Officers with those of our shareholders, to foster a long-term management orientation, and to promote sound corporate governance. For non-employee members of our Board, our Stock Ownership Guidelines provide an ownership target equal to the lesser of 5,000 shares or a value equivalent to five times the annual cash Board retainer. Non-employee members of our Board are expected to achieve their stock ownership targets within five years of becoming subject to these guidelines. The policy includes procedures for granting exemptions in the case of severe financial hardship. Ownership targets for our Named Executive Officers (including those serving on our Board) are described below under Compensation Discussion and Analysis—Stock Ownership Guidelines.

In determining ownership levels for each director under our Stock Ownership Guidelines, credit is provided for shares held outright, as well as the number of vested, but unexercised, stock options and share tracking awards. No credit is provided for restricted stock units until they vest. For purposes of vested, unexercised stock options and share tracking awards, shares will be calculated on an "as if exercised" basis, assuming a cashless exercise (in the case of stock options) and net of taxes (using an assumed 35% tax rate). As of March 15, 2018, all of our non-employee directors had met the ownership targets in our Stock Ownership Guidelines.

Meetings of our Board of Directors and Board Attendance at Annual Meetings of Shareholders

Our full Board held seven meetings during 2017. In addition, during 2017, our Audit Committee held six meetings, our Compensation Committee held seven meetings, and our Nominating and Governance Committee held three meetings. Each of our directors attended more than 75% of the total number of meetings of our Board and the committees on which he or she served during 2017. In accordance with applicable Nasdaq listing standards, the independent members of our Board met without management present four times during 2017.

Although attendance is not mandatory, our Board encourages all of its members to attend the annual meeting of shareholders. Eight of our directors attended our 2017 annual meeting of shareholders.

Shareholders are encouraged to address any director communications to our Corporate Secretary by overnight or certified mail, signature acceptance or return receipt required, at: United Therapeutics Corporation, Attention: Corporate Secretary, 1040 Spring Street, Silver Spring, Maryland 20910. Our

Corporate Secretary has the authority to disregard or take other reasonable action with respect to any inappropriate shareholder communications. After confirming the stock ownership of the author of the communication, our Corporate Secretary will review the appropriateness of a shareholder communication based on the relevance of the communication to Board decisions. If deemed an appropriate communication, our Corporate Secretary will submit the shareholder communication to our Lead Independent Director.

We amended our By-laws in 2015 to implement proxy access, which allows a shareholder or a group of up to 20 shareholders owning shares representing at least 3% of the outstanding voting stock of our company entitled to vote in the election of directors continuously for at least three years, to nominate and include in our Proxy Statement their own director nominees constituting up to 20% of the total number of directors then serving on our Board (or up to 25% if fewer than 10 directors are then serving on our Board), provided that the shareholder(s) and the nominee(s) satisfy the requirements in our By-laws. Our Board carefully considered the feedback we received from our shareholders in creating a thoughtfully designed and balanced approach to proxy access that mitigates the risk of abuse and protects the interests of all of our shareholders, while affording a meaningful proxy access right. Shareholders who wish to nominate directors for inclusion in our Proxy Statement in accordance with the procedures in our By-laws should follow the instructions under Shareholder Proposals and Director Nominations in this Proxy Statement.

In June 2015, as part of our Board's ongoing review of our corporate governance policies, we amended our By-laws to provide that director nominees shall be elected by a majority of votes cast in uncontested director elections. A majority of votes cast means that the number of votes cast for the director nominee's election must exceed the number of votes cast against that director nominee's election. In connection with this By-law amendment, our Board also adopted a director resignation policy set forth in our Corporate Governance Guidelines, providing that any director who is not elected by a majority of the votes cast is expected to tender his or her resignation to our Nominating and Governance Committee. Our Nominating and Governance Committee will recommend to the Board whether to accept or reject the resignation offer, or whether other action should be taken, considering all factors that the Committee believes are relevant. Our Board will act on our Nominating and Governance Committee's recommendation within 90 days following certification of the election results. Any director who tenders his or her resignation pursuant to our director resignation policy will not participate in the proceedings of either the Committee or the Board with respect to his or her own resignation offer.

In 2017, our non-employee director compensation program was comprised of three main elements:

Directors may also be compensated for special assignments from our Board. In 2017, no such special assignments occurred that involved compensation to a director. Employee directors do not receive any compensation for service on our Board in addition to their regular compensation as employees.

Our Compensation Committee and Nominating and Governance Committee generally review non-employee director compensation levels approximately once every two years, and final decisions with respect to any changes in non-employee director compensation levels are made by our Board upon the recommendation of our Compensation Committee and our Nominating and Governance Committee. In 2017, our Compensation Committee's independent consultant reviewed the market competitiveness of our non-employee director compensation program relative to our compensation peer group (as described in more detail below under Compensation Discussion and Analysis—Executive Compensation Framework—Compensation Peer Group). Based on this review, our Compensation Committee did not recommend any changes to the non-employee director compensation program in 2017. Our current non-employee director compensation levels were established by the Board in February 2016. The following table outlines the non-employee director compensation levels in effect for 2017:

Non-employee directors are eligible to receive equity-based awards under the United Therapeutics Corporation 2015 Stock Incentive Plan (the 2015 SIP), which was approved by our stockholders on June 26, 2015, as follows:

Previously, non-employee directors were also eligible to receive awards under the 2011 United Therapeutics Corporation Share Tracking Awards Plan (collectively with its predecessor plan adopted in 2008, the STAP), which settle only in cash. However, with the approval of our 2015 SIP, all equity-based awards beginning on June 26, 2015 have been granted in the form of stock options and RSUs.

The following table lists the compensation earned in 2017 by each non-employee director:

(1): Includes (as applicable) annual cash retainer and fees for serving on our Board, the committees of our Board, as a committee chairman and as Lead Independent Director.
(2): On June 28, 2017, each of our non-employee directors was granted a combination of stock options and/or RSUs. Each stock option had an exercise price of $132.30 per share and a grant date fair value of $49.08 per share. Each RSU had a grant date fair value of $132.30 per share. Amounts shown in these columns represent the aggregate grant date fair value of these stock options and RSUs, which were the only awards granted to non-employee directors in 2017, computed in accordance with applicable accounting standards. For a discussion of the valuation assumptions for stock options, see Note 9—Share-Based Compensation to the consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2017. We note that the aggregate grant-date fair value of equity awards in 2017 differed from the annual equity-based award value of $400,000 because the actual number of options and RSUs granted was based on an average stock price over a defined time period, rather than the closing stock price on the date of grant, which is used to calculate the fair value of the awards.

The following table shows the number of stock options, STAPs and RSUs outstanding for each non-employee director as of December 31, 2017:

We are asking our shareholders to vote on an advisory resolution, commonly known as a "Say-on-Pay" proposal, to approve executive compensation as reported in this Proxy Statement. Our Board and our Compensation Committee strongly value the opinions of our shareholders, and we have made substantial modifications to our executive compensation program specifically to address concerns raised by shareholders in previous years. Our Compensation Committee, which is responsible for designing and administering our executive compensation program, has designed our executive compensation program to provide a competitive and internally equitable compensation and benefits package that reflects company performance, job complexity and the value provided, while also promoting long-term retention, motivation and alignment with the long-term interests of our shareholders. Our company has grown revenue each year since 1998, and we believe the compensation program for our Named Executive Officers has been instrumental in helping us achieve strong business performance.

Please see the Letter from our Compensation Committee Chairman on the following page of this Proxy Statement to better understand how we have modified our programs based on feedback from our shareholders. We are pleased that changes to our compensation programs over recent years, in response to shareholder feedback, resulted in the approval of our 2016 and 2017 Say-on-Pay proposals. Similarly, although non-binding, we will consider the outcome of the 2018 Say-on-Pay vote in considering future compensation arrangements and decisions.

In connection with your vote on this proposal, we urge you to read the sections of this Proxy Statement entitled Letter from our Compensation Committee Chairman, Compensation Discussion and Analysis and the Summary Compensation Table and other related compensation tables and narratives that follow, which provide detailed information on the compensation of our Named Executive Officers. Our Compensation Committee and our Board of Directors believe that the policies and procedures articulated in the Compensation Discussion and Analysis, including the modifications we have made to our executive compensation programs, are effective in achieving our goals and that the compensation of our Named Executive Officers reported in this Proxy Statement has supported and contributed to both our recent and long-term success.

In accordance with Section 14A of the Exchange Act, and as a matter of good corporate governance, we are asking shareholders to approve the following advisory resolution at the Annual Meeting:

This advisory resolution is non-binding on our Board of Directors. Although non-binding, our Board and our Compensation Committee will review and consider the voting results when making future decisions regarding our executive compensation program. Based on the results of our 2017 shareholder advisory vote on the preferred frequency of holding future advisory votes to approve executive compensation, our Board of Directors has adopted a policy providing for an annual advisory resolution to approve executive compensation. Unless our Board modifies its policy on the frequency of future "Say-on-Pay" advisory votes, the next "Say-on-Pay" advisory vote will be held at our 2019 annual meeting of shareholders.

OUR BOARD OF DIRECTORS RECOMMENDS THAT YOU VOTE "FOR"
THE ADVISORY RESOLUTION TO APPROVE EXECUTIVE COMPENSATION.

On behalf of our Compensation Committee, I am pleased to report that 2017 was another successful year for United Therapeutics. We achieved all-time high annual revenues ($1.725 billion) representing approximately 8% year-over-year growth, driven by double-digit growth in revenues from four of our five commercial products. Profitability remained strong, and our balance of cash, cash equivalents and marketable securities grew from $1.05 billion to $1.43 billion from December 31, 2016 to 2017. We launched numerous research and development programs intended to develop new therapies and expand the use of our existing products in new indications. As a result, we are now undertaking seven simultaneous pivotal clinical trials—a record for our company. All of these advancements have continued to build a foundation and platform for future growth for our shareholders. Our past, ongoing, and future success is rooted in the strength of our leadership team, which has delivered consistently strong performance over time.

In this Proxy Statement, we are asking you to read the Compensation Discussion and Analysis section and to vote on an advisory resolution relating to our executive compensation program—this is commonly known as the "Say-on-Pay" proposal. In both 2016 and 2017, we received significant support for our Say-on-Pay proposal, underscoring the successful implementation of changes to our compensation program based on engagement with our shareholders. We have continued to engage with our shareholders on compensation matters, and our compensation program has continued to evolve—with 2017 marking our most significant compensation program changes ever. In this letter, I want to highlight the fundamental changes we have made to our compensation program in response to shareholder feedback. These changes include a shift in the timing of our equity incentive grants, causing a one-time overlap as stock options were awarded in 2017 for both the 2016 compensation year and the 2017 compensation year. Presented in our Summary Compensation Table, this one-time anomaly appears at first glance to include abnormally high compensation in 2017. The purpose of this letter is to ensure that shareholders understand the shift in compensation policy and associated benefits which are the driver of this one-time event.

As noted above, in 2017 we made a major shift in our equity grant practices. Historically, we established the size of an equity award at the start of the year for a performance year (e.g. Q1 2016) and then issued an award after the close of the fiscal year based on performance against pre-established milestone goals (e.g. Q1 2017). The award was then subject to time-based vesting for retention and incentivization to drive sustainable future performance. While these awards were entirely performance-based, some shareholders viewed these as time-based since they were granted after the performance was completed and were subject to additional time-based vesting. As a result of shareholder feedback and to enhance the performance aspect of these awards, we modified our equity award policy to be prospective in nature. This means that for the 2017 performance year, we made grants in March 2017 and these awards will only vest if the performance conditions are achieved over a prospective measurement period. However, this one-time transition from retrospective grants to prospective grants resulted in grants being issued in March 2017 to reward milestone performance under the 2016 performance year as well as to start the 2017 performance and pay cycle. Our implementation of this new policy is considered a best practice and is endorsed by shareholder advocacy thought leaders. Both sets of grants are presented in this year's Summary Compensation Table, and as a result, the table overstates the actual compensation set for 2017. Thus, it is important that shareholders review the Supplementary 2017 Summary Compensation Table (see page 44) to better understand the pay decisions implemented specifically for the 2017 pay cycle.

Also in 2017 and in direct response to shareholder feedback, we changed our equity program such that 100% of the awards are now tied to specific performance conditions. In particular, 50% of the awards are tied to the annual company-wide metrics under our Company-Wide Milestone Program and the remaining 50% are tied to a three-year performance profit metric. By using the annual milestones for the cash incentive and a portion of the long-term incentive, we reinforce the need for strong annual operating performance to build for the future. This reinforces our desire to keep our executives focused on our priorities as well as to keep the plan design simple and straightforward. We have also adopted a three-year performance metric for 50% of the equity award, to keep our executives focused on profitability over the longer term.

We are strong believers in pay-for-performance. While we felt that our previous program supported this belief, as noted above many of our shareholders did not view our equity incentive awards as performance-based. Our executive compensation program has always involved a predominant focus on at-risk pay, tied directly to company performance via our cash incentive and long-term incentive plans. With the changes noted above, we believe that shareholders and proxy advisory services should agree that our program is overwhelmingly performance-based. In 2017, our performance-based cash and equity incentives represented approximately 92% of the overall pay package for our Chief Executive Officer and approximately 86% for all Named Executive Officers. Cash incentives are awarded for the achievement of our Company-Wide Milestones, which are established at the beginning of the year. Our Milestones include objective components of revenue growth, profit growth, manufacturing capability, research and development progress and ethics/compliance. Our stock option

awards are also performance-based, with the stock options being an important incentive to create value for our shareholders as a growth company such as ours. The number of shares underlying the option must be earned based on the achievement of pre-specified operational and financial performance criteria, and the stock price must appreciate in order for executives to realize any value.

We value the opinions of our long-term shareholders. Over the past several years, we have worked with our management team to lead increased engagement with our shareholders on compensation matters. In the last year alone, we reached out to shareholders representing approximately 70% of our outstanding shares and met with shareholders representing approximately 30% of our outstanding shares. We have had valuable and constructive interactions with our shareholders and we have received and acted on the feedback each year. Our shareholders have communicated directly to me their delight with the performance of our company and our goal of evolving the executive compensation program, over time, in order to retain, motivate and incentivize our executive team that has consistently delivered market-leading, long-term performance. Over the past three years, we have made substantial changes to our executive compensation program based on extensive conversations with our shareholders. These changes are consistent with the principles outlined above, respond to the feedback and expectations of our shareholders, and are consistent with best practices. These changes continue to align and reinforce the key strategic and talent objectives for our company.

I hope the above information conveys the sincerity with which we have addressed the requests and ideas our shareholders have raised regarding our executive compensation program. On that note, I want to personally thank those shareholders with whom we have had the opportunity to meet over the past several years. As our responsiveness demonstrates, we very much value the dialogue. We implemented dramatic changes in 2017 which will benefit our company and its shareholders going forward. While there is an unfortunate, anomalous impact on the compensation values we are required to report for 2017, we hope this letter clarifies why this is so and provides an understanding of the one-time nature of that impact.

Please review the Compensation Discussion and Analysis beginning on the following page for further information and detail about our executive compensation program. We look forward to your continued support of United Therapeutics generally, and your support of our Say-on-Pay Proposal this year.

This Compensation Discussion and Analysis describes the compensation objectives and policies set by our Compensation Committee for our Named Executive Officers, including executive pay decisions and processes and all elements of our executive compensation program. It should be read in connection with the Letter from our Compensation Committee Chairman immediately preceding this section (referred to as the "Shareholder Letter"), which contains important information regarding changes we have made to our executive compensation program. In this Compensation Discussion and Analysis, the term "Compensation Committee" refers to the Compensation Committee of our Board of Directors, and the terms "we" and "our" refer to United Therapeutics. Our Named Executive Officers in 2017 consisted of the following individuals: Martine Rothblatt, Ph.D., Chairman and Co-Chief Executive Officer; James Edgemond, Chief Financial Officer and Treasurer (beginning with his promotion to this position in March 2015); Michael Benkowitz, President and Chief Operating Officer (beginning with his promotion to this position in June 2016); and Paul Mahon, J.D., Executive Vice President and General Counsel.

Company	2017	2018

ACADIA	ü	ü
Alexion Pharmaceuticals	ü	ü
Alkermes	ü	ü
Alnylam Pharmaceuticals	ü	ü
Amgen	ü	ü
Anacor	ü
Biogen	ü	ü
BioMarin Pharmaceutical	ü	ü
Bio-Techne	ü	ü
Celgene	ü	ü
Endo International	ü
Exelixis		ü
Gilead Sciences	ü	ü
Illumina	ü	ü
Incyte	ü	ü
Intercept Pharmaceuticals	ü
Ionis Pharmaceuticals	ü	ü
Jazz Pharmaceuticals	ü	ü
Juno	ü
Kite Pharma		ü
Medivation	ü
Mylan N.V.	ü	ü
Neurocrine	ü	ü
Opko Health		ü
PRA Health Sciences		ü
Regeneron Pharmaceuticals	ü	ü
Seattle Genetics	ü	ü
Shire	ü	ü
Tesaro		ü
Vertex Pharmaceuticals	ü	ü
Median Revenue ($MM)	$996.6	$1,226.7
United Therapeutics Revenue ($MM)	$1,507.3	$1,600.3
United Therapeutics Percentile Rank⁽¹⁾	59^th	57^th
Median Market Cap ($MM)	$9,857.0	$9,283.8
United Therapeutics Market Cap ($MM)	$4,972.1	$5,817.3
United Therapeutics Percentile Rank⁽¹⁾	33^rd	31^st

Our Compensation Committee has relied on a consistent approach to peer group selection, applying an objective external measure for selecting companies. This results in a number of peers being larger than our company based on market capitalization and/or revenue as well as a number of peers being smaller. Our goal each year is to provide a balanced view of companies placing our company within the peer group statistics of the 25^th to 75^th percentile for these key metrics. Furthermore, our Compensation Committee views it as critical to measure ourselves against industry leading peers (even if some are much larger than we are) because, in addition to being companies with which we compete

for talent, these larger companies are also our business competitors. Our commercial products compete with some of the largest biotechnology and pharmaceutical companies in the world, including Gilead Sciences Inc., the largest company in our peer group in terms of market capitalization. We have focused on both the revenue rank and market capitalization position given the range of companies in the peer group. By placing our company between the 40^th and 60^th percentile of our peer group for revenue, we believe the peer group reflects companies of similar scope and complexity. Given market capitalization volatility we seek to balance revenue rank and market capitalization ranking when setting pay levels on a per position basis.

At our 2017 annual meeting of shareholders, our shareholders voted in favor of our Say-on-Pay Proposal (80%). We were pleased with this result given the changes we had implemented based on shareholder feedback. As detailed in the Shareholder Letter beginning on page 24 of this Proxy Statement, we have continued our engagement with shareholders and have made further changes to our executive compensation programs for 2017 based on this ongoing dialogue. Over the last several years, the Chairman of our Compensation Committee has led an effort to engage with our shareholders, and in 2017 alone, we reached out to shareholders whose holdings represented approximately 70% of our then outstanding shares and ultimately held in-person discussions with shareholders whose holdings represented approximately 30% of our then outstanding shares. The purpose of these meetings was to gather feedback regarding our executive compensation and general governance policies, and to discuss the structure and design of our equity compensation program. This information was then shared with our Compensation Committee as it considered potential changes to our executive compensation program. Our Compensation Committee Chairman and members of management participated in these calls. Our Compensation Committee also considered the proxy voting reports from the shareholder advisory firms of Institutional Shareholder Services, Inc. and Glass, Lewis & Co., LLC with respect to our compensation programs. Our Compensation Committee held seven meetings in 2017, and the Chairman of our Compensation Committee held numerous additional meetings with management and its independent compensation consultant to determine the best way to continue to address shareholder feedback as the Compensation Committee evaluated our executive compensation programs.

Our Compensation Committee periodically assesses the effectiveness of our compensation policies and practices in achieving its pay-for-performance objective while aligning the interests of executive officers with those of shareholders, balancing short term and long-term elements, and maintaining market competitiveness. Our Compensation Committee also reviews risk mitigation and governance items, which are designed to help ensure that our compensation programs are functioning to achieve

such objectives. In conjunction with this assessment and review, we have adopted the following best practices:

	What We Do		What We Don't Do



✔	Design our executive compensation program to align pay and performance with more than 90% being performance contingent for our CEO	✘	No repricing or backdating of stock options
✔	Gather market data for the specific peers examining a range of pay between the 25^th and 90^th percentiles to understand the market conditions within the industry and for our labor market	✘	No liberal share recycling under 2015 Stock Incentive Plan
✔	Maintain an appropriate balance between short-term and long-term compensation which discourages short-term risk taking at the expense of long-term results
✔	Grant performance-contingent equity based on company milestones and multi-year performance

✔	Establish threshold, target and stretch company goals; we require a minimum level of performance for any payment under the cash incentive plan	✘	No vesting prior to the first anniversary of grant, subject to limited exceptions

✔	Maintain stock ownership guidelines to align executive officer and share ownership with that of our directors and our shareholders	✘	No grants of equity during trading blackout periods

✔	Prohibit hedging and pledging by executives and directors	✘	No discounted or reloaded stock options

✔	Employ a compensation recovery, or clawback, policy*	✘	No excessive perquisites
✔	Conduct annual risk assessments of our compensation policies and practices	✘	No excise tax gross ups
✔	Hold Compensation Committee executive sessions without management	✘	No guaranteed base salary and/or bonus payments
✔	Engage an independent compensation consultant who reports directly to the compensation committee

Pay-for-performance and a focus on total direct compensation are fundamental to our compensation philosophy. The compensation program for our Named Executive Officers is structurally tied to performance, on a one-year and a three-year basis. This places the vast majority of pay "at-risk", consisting of performance-based cash and equity incentives under our one-year Milestone grant program and additional equity incentives under our three-year cash profit equity grant. These awards are dependent on achieving operating performance to remain focused on delivering results for our shareholders in the near-term and longer-term. Total target direct compensation for 2017 is shown below and reflects base salary, the target annual cash incentive award and the grant date fair value of equity awards granted during the year. Our Compensation Committee takes a holistic approach to compensation and seeks to ensure that the aggregate level of pay across all pay elements is meeting the stated objectives. Our Compensation Committee does not have a formulaic approach to allocating pay between the various elements. Instead, our Compensation Committee applies its business judgment and experience to establish a total compensation package for each Named Executive Officer which it believes is appropriate.

The components of our Named Executive Officers' target total direct compensation are base salary and variable performance-based compensation, including cash incentives and long-term incentive compensation, in the form of performance-based stock options. The following table shows our Named Executive Officers' base salaries and target performance-based compensation for 2017 and the amount of any increase of such compensation over 2016. The basis for our Compensation Committee's decisions with respect to each of these components for 2017 is discussed in greater detail below.

Base salary is the primary fixed element of the compensation packages for our Named Executive Officers. Our Compensation Committee reviews and establishes base salary levels for our Named Executive Officers each year taking into consideration one or more of the following factors, depending on the circumstances: (i) a qualitative evaluation of individual performance, including contribution to the advancement of corporate objectives, impact on financial results, and strategic accomplishments; (ii) our overall performance, financial condition and prospects; (iii) the annual compensation received by executives holding comparable positions at our peers as described in the section entitled Overview of our 2017 Executive Compensation Program above; (iv) our annual company-wide budget for salary increases; and (v) the input of our Chief Executive Officer (in the case of the other Named Executive Officers). Base salaries are also typically reviewed when there is a material change in the executive's responsibilities during the year.

In early 2017, our Compensation Committee approved salary increases for all of our Named Executive Officers, providing a 5% increase for Dr. Rothblatt, a 4% increase for Mr. Edgemond, a 15% increase for Mr. Benkowitz and a 3% increase for Mr. Mahon, effective March 2017. Mr. Benkowitz' salary increase reflected the increase in his responsibilities following his promotion to President and Chief Operating Officer, and his significant contribution to the business in 2017. The remaining salary increases were determined based on a review of competitive pay positioning, taking into consideration internal pay equity among Named Executive Officers and the importance of the Named Executive Officers.

Each year, our Compensation Committee establishes cash incentive award targets for each of our Named Executive Officers, taking into consideration the same factors it uses to determine base salaries (other than our company-wide budget for salary increases). For 2017, our Compensation Committee initially established cash incentive award targets for our Named Executive Officers as a percentage of base salary in early 2017, at the levels shown in the Summary 2017 Target Total Direct Compensation table above.

These stated incentive targets are comparable to those of executives holding similar roles and levels of responsibility at our peer group companies. Cash incentives are earned for achieving our Company-Wide Milestones (described below) and are subject to a threshold, or minimum, level of performance that must be achieved before any awards are made. In addition, each of our Named Executive Officers has the opportunity to earn up to 150% of their target cash incentive award for 2017, based on above-target performance on our cash profit and revenue-based milestones. We believe that by setting a threshold level of performance as well as a maximum under the plan we have aligned these policies with market norms and have also responded to feedback from our shareholders.

The Milestones (or performance goals) are generally intended to create company-wide incentives relating to significant corporate objectives, such as (i) financial performance and growth; (ii) research and development programs, manufacturing capabilities and other operational metrics and goals; and (iii) ethical conduct. Our Compensation Committee approved the specific goals and weightings based on management input at the beginning of the year based on a desire to reflect core performance measures and priorities for the business for the fiscal year, including our commitment to compliance, and to set goals that translate most directly into short-, medium-and long-term value growth.

The Milestone performance targets are difficult to meet and require significant leadership and execution on the part of our Named Executive Officers. Based on these factors, our Compensation Committee established the following Company-Wide Milestones and weightings for 2017:

2017 Company-Wide Milestones

**Milestone 1—Cash Profits:* Achieve the cash profit level for 2017 included in our long-range business plan ($950 million)	20	%
**Milestone 2—Financial Growth:** Superior financial growth as evidenced by achieving the net revenues for 2017 included in our long-range business plan ($1.75 billion)	20	%
**Milestone 3—Manufacturing:** Adequate manufacturing capabilities, evidenced by a two-year inventory of Remodulin, Tyvaso and Orenitram finished drug product and passing all GMP-related FDA inspections at our facilities without any issues that prevent the use or approval of any of our drug products	20	%
**Milestone 4—Research & Development:** Conduct insightful research and development programs, taking into account regulatory approvals, label extensions and the quantity and quality of trials that support our business goals	20	%
**Milestone 5—Ethics:** Accomplish each of the above Milestones in an ethical manner, and respond, as appropriate, to any compliance-related investigations	20	%

Our Compensation Committee has carefully crafted these Milestones, which represent rigorous, objective standards by which to measure company and executive officer performance. Our Compensation Committee believes that all five Milestones are strategically important to our continued success and therefore should be weighted equally in determining incentive awards. Cash profits and financial growth objectives are important to maintaining industry-leading financial performance, and our 2017 goals are tied to our long-term strategic objectives, which include aggressive revenue growth targets over four-, eight- and twelve-year time horizons. Our manufacturing Milestone is intended to ensure a continuous supply of our treprostinil-based therapies, which generate the vast majority of our revenues. Our research and development Milestone is intended to ensure that we have a robust pipeline of products that has the capability of delivering future revenues sufficient to drive continued, industry-leading growth. Finally, our ethics milestone recognizes the importance of maintaining an effective compliance program as individual fines from government investigations of pharmaceutical companies have become increasingly material. Importantly, four of our Milestones create clear,

objective standards for measuring company performance, while the fifth (Ethics) is based on a qualitative assessment.

The details of our framework for determining 2017 Milestone performance are provided below:

Milestone	Award Determination Criteria

Cash Profits	·	< 95% of Goal: 0% credit (below threshold)
	·	95% of goal: 50% credit (at threshold)
	·	95% to 100% of Goal: partial credit (linear interpolation, between threshold and target)
	·	100%+ of Goal: 100% credit (target)
Financial Growth	· · ·	< $1.6 billion: 0% credit (below threshold) $1.6 billion: 50% credit (at threshold) $1.6 billion to $1.75 billion: partial credit (linear interpolation, between threshold and target)
	·	100%+ of Goal ($1.75 billion): 100% credit (at target)
Manufacturing	·	Award pro rata credit based on number of quarters for which: (1) pre-specified inventory levels are achieved (i.e., 2-year supply of Orenitram, Remodulin and Tyvaso); and (2) we pass any GMP-related FDA inspections
Research & Development*	· · ·	< 75% of Goal: 0% credit (below threshold) 75% of Goal: 50% credit (at threshold) 75% to 100% of Goal: pro rata credit (linear interpolation, between threshold and target)
	·	100%+ of Goal: 100% credit (at target)
Ethics	·	Based on a qualitative assessment of the effectiveness of the overall compliance program as determined by our Nominating and Governance and Compensation Committees

Under the terms of our Company-Wide Milestone Program, our Compensation Committee has the authority to exercise negative (downward) discretion in the event of partial attainment under any of the Milestones.

For 2017, above-target cash incentive awards were possible (up to 150% of target) based only on the achievement of financial performance against the pre-established financial growth and cash profit goals, as follows:

For 2017, our Compensation Committee determined that 98.5% of the Milestones were achieved, in accordance with the following analysis:

	Performance

1	2017 cash profits were $1.180 billion, representing 124% of the target of $950 million.	100	%	20	%	20	%
2	2017 net revenues for Remodulin, Tyvaso, Adcirca, Orenitram and Unituxin were $1.725 billion, representing 98.5% of the target of $1.75 billion, resulting in 92.5% credit based on linear interpolation	92.5	%	20	%	18.5	%
3	Maintained greater than two-year inventory of all strengths of Remodulin, Tyvaso and Orenitram and passed all FDA inspections at our facilities	100	%	20	%	20	%
4	Achieved 33 R&D points compared to a goal of 38 points (before applying the 1.2 normalization factor). While we did not achieve approval for the Implantable System for Remodulin as planned, we continued enrolling several important pivotal studies (e.g., FREEDOM-EV trial of Orenitram (phase 3/4), BEAT study of esuberaprost (phase 3), INCREASE study of Tyvaso (phase 2/3), DISTINCT study of dinutuximab in small cell lung cancer (phase 2/3)) and commenced several important new studies (e.g., SAPPHIRE gene therapy study (phase 2/3), SOUTHPAW study of Orenitram in WHO Group 2 pulmonary hypertension). We also progressed our phase 3 program relating to the RemUnity pump, our EVLP study (phase 2) and our efforts to develop a pain-free version of Remodulin called RemoPro.	100	%	20	%	20	%
5	Based on an assessment by our Nominating and Governance Committee, our company was found to have performed in an ethical manner, and with an effective compliance program.	100	%	20	%	20	%

Total						98.5	%

Our Named Executive Officers have the ability to earn above target pay only when we exceed our financial targets under Milestones 1 and 2 above. For 2017, our cash profits of $1.180 billion exceeded both target ($950 million) and maximum ($1.045 billion), therefore the additional 25% financial multiplier was achieved for this metric. The revenues of $1.725 billion were modestly below target ($1.75 billion), therefore no additional financial multiplier was achieved for this performance. The aggregate financial multiplier for 2017 was 125% (100% + 25%).

The cash incentive awards earned by our Named Executive Officers and approved by our Compensation Committee for the 2017 performance year were as follows:

Our long-term incentive compensation program is structured to support our pay-for-performance and shareholder alignment objectives. As such, beginning in 2017 our program consists entirely of performance-based stock options under the United Therapeutics Corporation 2015 Stock Incentive Plan (the 2015 SIP). For the 2017 performance period, we granted performance-based stock options to each Named Executive Officer based on the target equity values shown above under 2017 Target Total Direct Compensation, converted into a number of stock options based on a Black-Scholes-Merton value, which uses the average closing price of our common stock for the month of February 2017. Our Compensation Committee does not have a set benchmark or formula for setting the long-term incentive award target for these individuals. It reviews and establishes long-term incentive target opportunities based on several factors, including: (i) the fair value of the long-term target opportunity in relation to our peer group; (ii) past grant levels including the retention value of these holdings; (iii) individual and company performance; and (iv) the potential gain to be realized from these awards based on the appreciation in the price of our common stock. 2017 awards were granted in two forms of performance-based stock options, as follows:

The following table shows the number of Cash Profit Performance Options granted to each Named Executive Officer in March 2017 for the 2017 equity opportunity at threshold, target and maximum performance levels:

Both types of stock options expire 10 years from the date of grant, subject to earlier expiration upon termination of employment with us.

As a result of these actions, actual total direct compensation (defined as 2017 base salary, plus cash incentive award paid in 2018 for 2017 performance, plus the grant date fair value of Milestone Performance Options and Cash Profit Performance Options granted in 2017 for the 2017 performance period) for our Named Executive Officers approximated the 90^th percentile of our peer group in the case of our Chief Executive Officer and General Counsel, and between the 50^th and 75^th percentile of our peer group for our other Named Executive Officers. Our Compensation Committee believes this was appropriate given the pay-for-performance design of our compensation arrangements, where a larger portion of Named Executive Officers' compensation on average is performance-based when compared to our peer group, and our track record of extraordinary, long-term performance against our internal goals and relative to our peers. Additionally, our annual compensation levels and composite performance for 2017 are extremely well aligned in relation to our peer group.

Our long-term incentive award grant timing is designed so that awards are granted after the market has had an opportunity to react to our announcement of annual earnings. We also believe this timing helps us avoid broad internal communication of highly confidential financial results prior to public announcement of our annual financial results. All long-term incentive awards granted to our Named Executive Officers and other employees have an exercise price equal to the closing price of our common stock on the Nasdaq on the date of grant or, if the award is granted on a date when the Nasdaq is not open, an exercise price equal to the closing price of our common stock on the Nasdaq on the preceding trading day.

As a general matter, awards to our Named Executive Officers for a given year have historically been granted on March 15^th of the following calendar year (or the preceding trading day if markets are not open on March 15^th). As a result, long-term incentive awards for our Named Executive Officers, as discussed in our 2017 Proxy Statement, were granted on March 15, 2017, and these awards are shown

in the Summary Compensation Table and the tables thereafter in this Proxy Statement. We recommend shareholders also examine the Supplementary 2017 Summary Compensation Table below to better understand the actual decisions made for 2017 given that 2017 was a transition year and resulted in grants for 2016 performance (retrospective pay) as well as grants for 2017.

The benefits offered to our Named Executive Officers are substantially the same as those offered to all employees, with the exception of the supplemental executive retirement plan (SERP) discussed in the section entitled Supplemental Executive Retirement Plan below. We provide a tax-qualified retirement plan (a 401(k) plan) and medical and other benefits to executives that are generally available to other full-time employees. Under our 401(k) plan, all employees are permitted to contribute up to the maximum amount allowable under applicable law (i.e., $18,000 in 2017 or $24,000 for eligible participants who are age 50 or older). We make matching contributions equal to 40% of eligible employee contributions with such matching contributions vesting 33¹/3% per year based on years of service, not the amount of time an employee has participated in the 401(k) plan. Therefore, once an employee completes three years of service, his or her account is fully vested, and any future matching funds will vest immediately. The 401(k) plan and other generally available benefits programs allow us to remain competitive for executive talent. We also provide limited perquisites to our Named Executive Officers, including participation in either our vehicle lease program, which covers the monthly lease payment and cost of insurance and maintenance on vehicles, or a monthly car allowance of up to $1,000. Our Compensation Committee believes that the availability of these benefit programs generally enhances executive recruitment, retention, productivity and loyalty to us.

For additional details on certain benefits and perquisites received by our Named Executive Officers, see the Summary Compensation Table below.

We maintain our SERP for select executives to enhance the long-term retention of individuals who have been and will continue to be vital to our success. Currently, only our Named Executive Officers and four other members of senior management participate in the SERP. The SERP provides each participant with a lifetime annual payment after retirement (or at his or her election, a lump-sum payment) of up to 100% of final average three-year gross salary less estimated social security benefit, provided that he or she is employed by us or one of our affiliates until age 60. Participants in the SERP are prohibited from competing with us or soliciting our employees for a period of twelve months following his or her termination of employment (or, if earlier, upon attainment of age 65). Violation of this covenant will result in forfeiture of all benefits under the SERP.

Additional details regarding the SERP, including provisions in connection with a participant's death or disability or change in control of our company, are provided under the Pension Benefits in 2017 table below.

Each of our Named Executive Officers is eligible for certain severance payments in the event his or her employment terminates under specified circumstances, including in connection with a change in control, as provided in their employment agreements as well as the terms of the SERP, the 1997 United Therapeutics Corporation Amended and Restated Equity Incentive Plan (EIP), the 2015 SIP and the STAP. These payments vary based on the type of termination but may include cash severance, stock option and STAP vesting acceleration, SERP vesting acceleration, and/or continuation of health and other benefits.

Our Compensation Committee approved these arrangements in order to promote the loyalty and productivity of our Named Executive Officers and to align executive and shareholder interests by enabling executives to consider corporate transactions that are in the best interests of our shareholders and other constituents of our company without undue concern about whether the transaction may jeopardize their employment. Our Compensation Committee wants our Named Executive Officers to be free to think creatively and promote the best interests of our company without worrying about the impact of those decisions on their employment.

Details regarding severance and change in control arrangements for our Named Executive Officers are contained in the text following the Potential Payments Upon Termination or Change in Control table below.

As noted above under Board of Directors, Committees, Corporate Governance—Stock Ownership Guidelines, in 2011 our Board adopted Stock Ownership Guidelines in order to further align the financial interests of our directors and executive officers with those of our shareholders, to foster a long-term management orientation, and to promote sound corporate governance. Our Board amended the Stock Ownership Guidelines in 2016 in light of changes in the composition of our executive management team. As amended, our Stock Ownership Guidelines set targets for each executive officer according to the lesser of a multiple of base salary or fixed number of shares of common stock as follows:

In determining ownership levels for each executive officer, credit is provided for shares held outright, as well as the number of vested, but unexercised, stock options and STAP awards. For purposes of vested, unexercised stock options and STAP awards, shares will be calculated on an "as if exercised" basis, assuming a cashless exercise (in the case of stock options) and net of taxes (using an assumed 35% tax rate). Executive officers are expected to achieve their Stock Ownership Guideline target within five years of becoming subject to this policy. The policy provides procedures for granting exemptions in the case of severe financial hardship. As of March 15, 2018, all of our Named Executive Officers had met the ownership targets in our Stock Ownership Guidelines or were on track to do so within the time permitted.

For fiscal year 2017 and prior years, Section 162(m) of the Internal Revenue Code (the Code) generally limited the deductibility of compensation to $1 million per year for certain of our named executive officers, unless compensation in excess of the limit qualified as "performance-based compensation."

While our Compensation Committee considers the impact of this tax treatment, the primary factor influencing program design is the support of our business objectives. Generally, whether incentive compensation will be deductible under Section 162(m) of the Code will be a consideration, but not the decisive consideration, with respect to our Compensation Committee's compensation determinations. Accordingly, our Compensation Committee retains flexibility to structure our compensation programs in a manner that is not tax-deductible in order to achieve a strategic result that our Compensation Committee determines to be more appropriate. For example, with respect to the "performance-based

compensation" exception, awards granted under the annual cash incentive plan and the STAP historically have not met all of the requirements for deductibility under the Code, and therefore may not be deductible, even though we consider annual cash incentive awards and STAP awards to be based on performance.

Beginning in 2015, our cash incentive structure was intended to enable us to deduct such awards paid to our Named Executive Officers. Furthermore, following shareholder approval of the 2015 SIP, we structured equity-based awards to our Named Executive Officers in a manner intended to be deductible by us. The rules and regulations promulgated under Section 162(m) of the Code are complicated, however, and subject to change from time to time, sometimes with retroactive effect. As such, there can be no guarantee that any award intended to qualify as performance-based compensation under Section 162(m) of the Code will so qualify. Furthermore, it is anticipated that changes to the tax laws effective as of January 1, 2018 that eliminate the exception for performance-based compensation will have an impact on Section 162(m) deductibility going forward. These changes could, but may not, impact compensation decisions for fiscal 2018 and beyond.

The Compensation Committee of our Board of Directors has reviewed and discussed the Compensation Discussion and Analysis required by Item 402(b) of Regulation S-K and contained within this Proxy Statement with management and, based on such review and discussions, our Compensation Committee recommended to our Board of Directors that the Compensation Discussion and Analysis be included in this Proxy Statement and incorporated into United Therapeutics' Annual Report on Form 10-K for the year ended December 31, 2017.

The following table shows compensation information for 2015, 2016 and 2017 for our Named Executive Officers, calculated in accordance with SEC regulations. We refer your attention to the Supplementary 2017 Summary Compensation Table that immediately follows for an understanding of 2017 compensation in a way that eliminates the effect of a one-time overlap in equity awards for the 2016 and 2017 performance periods, due to a transition in our equity compensation program to entirely performance-based awards using prospective performance conditions.

Name and Principal Position		Salary⁽¹⁾ ($)				Option/ STAP Awards⁽²⁾ ($)		Non-Equity Incentive Plan Compensation⁽³⁾ ($)		Change in Pension Value and Nonqualified Deferred Compensation Earnings⁽⁴⁾ ($)		All Other Compensation⁽⁵⁾ ($)		Total ($)

Martine Rothblatt	2017	$	1,163,707	⁽⁶⁾	—	$	33,122,078	$	1,598,163	$	1,239,653	$	9,600	$	37,133,201
Chairman and Chief	2016	$	1,226,949	⁽⁶⁾	—	$	12,583,891	$	992,464	$	611,425	$	9,600	$	15,424,329
Executive Officer	2015	$	1,078,099	⁽⁶⁾	—		—	$	1,171,152		—	$	18,626	$	2,267,877
James Edgemond⁽⁷⁾	2017	$	620,833		—	$	6,583,317	$	577,148	$	854,747	$	17,000	$	8,653,045
Chief Financial Officer	2016	$	591,014		—	$	2,097,315	$	360,000	$	1,039,675	$	21,450	$	4,109,454
and Treasurer	2015	$	380,146		—	$	2,402,371	$	216,000		N/A	$	13,400	$	3,011,917
Michael Benkowitz⁽⁸⁾	2017	$	733,333		—	$	9,017,790	$	738,750	$	1,043,171	$	24,433	$	11,557,477
President and Chief Operating Officer	2016	$	568,417		—	$	3,570,563	$	416,000	$	508,653	$	287,522	$	5,351,155
Paul Mahon	2017	$	815,950		—	$	9,977,780	$	656,256	$	1,399,858	$	21,600	$	12,871,444
Executive Vice President	2016	$	942,724		—	$	5,243,288	$	413,764	$	1,006,819	$	21,600	$	7,628,195
and General Counsel	2015	$	760,201		—	$	6,954,075	$	495,785	$	303,644	$	17,800	$	8,531,505

(1): Increases in base salaries for each of our Named Executive Officers became effective on March 1, 2016 and 2017. In addition, increases in base salaries for Dr. Rothblatt became effective on January 1, 2015, and for Messrs. Mahon and Edgemond became effective on March 1, 2015. Finally, an additional salary increase for Mr. Benkowitz became effective June 26, 2016, upon his promotion to President and Chief Operating Officer, and Mr. Edgemond also received a base salary increase at that time. Therefore, a portion of the base salary shown for each year reflects the salary level for the previous year. In the case of Dr. Rothblatt and Messrs. Edgemond, Benkowitz and Mahon, amounts shown for 2016 also include $117,075, $60,074, $75,256 and $152,125 in accrued but unused vacation time that was cashed out in 2016 as a result of the elimination of our paid time off policy.
(2): Amounts shown represent the aggregate grant date fair value of stock options and STAP awards granted in each reported year, computed in accordance with applicable accounting standards. For a discussion of valuation assumptions for stock options and STAP awards for 2017 see Note 9—Share-Based Compensation to the consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2017. The stock options were awarded under our 2015 SIP and the STAP awards were granted under the STAP. 2017 was a transition year where we issued equity awards in March 2017 based on 2016 performance (based on the timing of our historical program), as well as awards reflecting each Named Executive Officer's 2017 equity award opportunity. See the Grants of Plan-Based Awards in 2017 table for more information on stock options granted to our Named Executive Officers in 2017. The value of 2017 stock option awards with performance conditions are reported at target, calculated using the Black-Scholes-Merton value in accordance with GAAP. For awards granted in respect of the 2016 performance year, target and maximum are equivalent. For awards granted in respect of the 2017 performance year, the number of shares earned may exceed target for "stretch" performance, up to a maximum number of shares. If the maximum number of shares were used in calculating the Black-Scholes-Merton value of these awards, the grant date fair value would be as follows:

2017 reflect cash earned in respect of 2017 performance but paid in March 2018. For information on the amounts earned for 2017, see the section entitled Cash Incentive Award Program in the Compensation Discussion and Analysis above.

(4): Amounts shown represent the change in the actuarial present value of retirement benefits under the SERP calculated in accordance with GAAP under SEC requirements. The assumptions used in calculating the change in the actuarial present value of SERP benefits are described in the footnotes to the Pension Benefits table below. Dr. Rothblatt's change in value was negative (-$245,203) and thus is reported as zero in 2015 in accordance with SEC rules. In addition, Mr. Edgemond was added to the SERP effective July 1, 2016. The change in pension value from year to year as reported in the table will vary based on these assumptions and may not represent the value that a Named Executive Officer will actually accrue or receive under the SERP.
(5): The amounts shown represent the aggregate incremental cost that can be attributed to lease, insurance and maintenance payments made on vehicles used by a Named Executive Officer or for monthly automobile allowances, and for travel expenses for family members to our functions (collectively, the perquisites), and "matching contributions" under our 401(k) Plan equal to 40% of each participant's qualifying salary contributions. In the case of Mr. Benkowitz, the amount shown also includes $275,322 in relocation benefits during 2016 and $6,233 in 2017, as Mr. Benkowitz relocated from California to North Carolina in connection with his promotion to President and Chief Operating Officer.
(6): Our Canadian subsidiary pays a portion of Dr. Rothblatt's total base salary in the amount of 120,000 Canadian dollars. The value of this portion in U.S. dollars has been estimated for the purposes of disclosure here by using the spot exchange rate on the dates on which Dr. Rothblatt was paid. In 2015, 2016 and 2017, our Canadian subsidiary paid the equivalent of US$93,699, US$89,308 and US$92,407 of Dr. Rothblatt's total base salary, respectively.
(7): Mr. Edgemond was promoted to Chief Financial Officer and Treasurer on March 13, 2015. Amounts reported for fiscal year 2015 reflect compensation paid to Mr. Edgemond during the entirety of 2015.
(8): Mr. Benkowitz was promoted to President and Chief Operating Officer effective June 26, 2016. Amounts reported for fiscal year 2016 reflect compensation paid to Mr. Benkowitz during the entirety of 2016.

As noted above in the Letter from our Compensation Committee Chairman, 2017 reflected a transition year where we issued equity awards in March 2017 based on 2016 performance (based on the timing of our historical program), as well as awards reflecting each Named Executive Officer's 2017 equity award opportunity, all of which are subject to prospective, pre-established performance conditions. In order to provide a clear summary of 2017 compensation that eliminates the effect of this one-time overlap, the following table presents 2017 compensation information for each Named Executive Officer exactly as shown above in the Summary Compensation Table, except that the Option/STAP Awards column only shows the grant date value of the 2017 Milestone Performance Options and 2017 Cash Profit Performance Options. The equity awards granted in 2017 related to 2016 equity opportunities have been eliminated.

Name and Principal Position		Salary⁽¹⁾ ($)				Option/ STAP Awards⁽²⁾ ($)		Non-Equity Incentive Plan Compensation⁽³⁾ ($)		Change in Pension Value and Nonqualified Deferred Compensation Earnings⁽⁴⁾ ($)		All Other Compensation⁽⁵⁾ ($)		Total ($)

Martine Rothblatt	2017	$	1,163,707	⁽⁶⁾	—	$	13,922,278	$	1,598,163	$	1,239,653	$	9,600	$	17,933,401
Chairman and Chief Executive Officer
James Edgemond	2017	$	620,833		—	$	2,983,354	$	577,148	$	854,747	$	17,000	$	5,053,082
Chief Financial Officer and Treasurer
Michael Benkowitz	2017	$	733,333		—	$	3,977,842	$	738,750	$	1,043,171	$	24,433	$	6,517,529
President and Chief Operating Officer
Paul Mahon	2017	$	815,950		—	$	3,977,842	$	656,256	$	1,399,858	$	21,600	$	6,871,506
Executive Vice President and General Counsel

(3): Amounts shown represent the total cash awards earned by each Named Executive Officer under our Company-Wide Milestone Program for the year, although the awards were not paid until March of the following year. The payouts were determined based on our attainment of specific, pre-established performance Milestones. For example, the amounts reported for 2017 reflect cash earned in respect of 2017 performance but paid in March 2018. For information on the amounts earned for 2017, see the section entitled Cash Incentive Award Program in the Compensation Discussion and Analysis above.
(4): Amounts shown represent the change in the actuarial present value of retirement benefits under the SERP calculated in accordance with GAAP under SEC requirements. The assumptions used in calculating the change in the actuarial present value of SERP benefits are described in the footnotes to the Pension Benefits table below. The change in pension value from year to year as reported in the table will vary based on these assumptions and may not represent the value that a Named Executive Officer will actually accrue or receive under the SERP.
(5): The amounts shown represent the aggregate incremental cost that can be attributed to lease, insurance and maintenance payments made on vehicles used by a Named Executive Officer or for monthly automobile allowances, and for travel expenses for family members to our functions (collectively, the perquisites), and "matching contributions" under our 401(k) Plan equal to 40% of each participant's qualifying salary contributions. In the case of Mr. Benkowitz, the amount shown also includes $6,233 in relocation benefits during 2017, as Mr. Benkowitz relocated from California to North Carolina in connection with his promotion to President and Chief Operating Officer.
(6): Our Canadian subsidiary pays a portion of Dr. Rothblatt's total base salary in the amount of 120,000 Canadian dollars. The value of this portion in U.S. dollars has been estimated for the purposes of disclosure here by using the spot exchange rate on the dates on which Dr. Rothblatt was paid. In 2017, our Canadian subsidiary paid the equivalent of US$92,407 of Dr. Rothblatt's total base salary.



				Estimated Future Payouts Under Non-Equity Incentive Plan Awards						Estimated Future Payouts Under Equity Incentive Plan Awards							Exercise or Base Price of Stock Option Awards ($/Sh)		Grant Date Fair Value of Stock Option Awards⁽⁶⁾ ($)
Name	Grant Date			Threshold⁽⁵⁾ ($)		Target⁽⁵⁾ ($)		Maximum⁽⁵⁾ ($)		Threshold (#)		Target (#)		Maximum (#)			Exercise or Base Price of Stock Option Awards ($/Sh)		Grant Date Fair Value of Stock Option Awards⁽⁶⁾ ($)
Martine Rothblatt		03/15/17	⁽¹⁾													240,000	$	146.03	$	13,360,800
		03/15/17	⁽²⁾								50,000		100,000		100,000		$	146.03	$	5,839,000
		03/15/17	⁽³⁾								N/A		122,061		183,092		$	146.03	$	6,795,136
		03/15/17	⁽⁴⁾								61,031		122,061		244,122		$	146.03	$	7,127,142
		N/A	⁽⁵⁾	$	649,000	$	1,298,000	$	1,947,000
James Edgemond		03/15/17	⁽¹⁾													45,000	$	146.03	$	2,505,150
		03/15/17	⁽²⁾								9,375		18,750		18,750		$	146.03	$	1,094,813
		03/15/17	⁽³⁾								N/A		26,156		39,234		$	146.03	$	1,456,105
		03/15/17	⁽⁴⁾								13,078		26,156		52,312		$	146.03	$	1,527,249
		N/A	⁽⁵⁾	$	234,375	$	468,750	$	703,125
Michael Benkowitz		03/15/17	⁽¹⁾													63,000	$	146.03	$	3,507,210
		03/15/17	⁽²⁾								13,125		26,250		26,250		$	146.03	$	1,532,738
		03/15/17	⁽³⁾								N/A		34,875		52,312		$	146.03	$	1,941,491
		03/15/17	⁽⁴⁾								17,438		34,875		69,750		$	146.03	$	2,036,351
		N/A	⁽⁵⁾	$	300,000	$	600,000	$	900,000
Paul Mahon		03/15/17	⁽¹⁾													75,000	$	146.03	$	4,175,250
		03/15/17	⁽²⁾								15,625		31,250		31,250		$	146.03	$	1,824,688
		03/15/17	⁽³⁾								N/A		34,875		52,312		$	146.03	$	1,941,491
		03/15/17	⁽⁴⁾								17,438		34,875		69,750		$	146.03	$	2,036,351
		N/A	⁽⁵⁾	$	266,500	$	533,000	$	799,500

(1): This award of stock options represents 75% of the Named Executive Officer's 2016 equity incentive award opportunity, was awarded based upon 2016 performance under the Company-Wide Milestone Program, and vests in equal installments over a three-year period. As described in the Compensation Discussion and Analysis above, as a general matter, prior to fiscal 2017, awards to our Named Executive Officers with respect to the performance achieved in a given fiscal year were historically granted on March 15^th of the following calendar year. As a result, as discussed in our 2017 Proxy Statement, these stock options were granted on March 15, 2017 based on the 2016 performance year.
(2): The award of stock options represents 25% of the Named Executive Officer's 2016 equity incentive award opportunity and is subject to a three-year performance threshold tied to average cash profit margin. To the extent earned, these stock options vest at the end of the three-year performance period. Target and maximum amounts are identical, given there was no additional incentive tied to above-target performance. As described in the Compensation Discussion and Analysis above, as a general matter, prior to fiscal 2017, awards to our Named Executive Officers with respect to the performance achieved in a given fiscal year were historically granted on March 15^th of the following calendar year. As a result, as discussed in our 2017 Proxy Statement, these stock options were granted on March 15, 2017 in respect of 2016 performance.
(3): This award of stock options represents 50% of the Named Executive Officer's 2017 equity incentive award opportunity and was subject to a one-year performance period tied to achievement of the 2017 Company-Wide Milestones. To the extent earned, these stock options vest in equal installments over a three-year period from the date of grant. These awards do not have an overall threshold amount, although individual milestones within the 2017 Company-Wide Milestone program are each subject to performance threshold in order to receive partial credit for the respective milestone. See the Compensation Discussion and Analysis above for details on the achievement of the Company-Wide Milestones.
(4): This award of stock options represents 50% of the Named Executive Officer's 2017 equity incentive award opportunity and is subject to a three-year performance threshold tied to average cash profit margin. To the extent earned, these stock options vest at the end of the three-year performance period.
(5): Actual cash incentive awards earned under the program in 2017 are reported in the Summary Compensation Table under the column entitled "Non-Equity Incentive Plan Compensation."
(6): The grant date fair value of stock options is generally the amount that we will recognize as an expense over the award's vesting period assuming target performance levels, computed in accordance with applicable accounting standards.

Narratives to Summary Compensation Table and Grants of Plan-Based Awards in 2017 Table

The material terms of each Named Executive Officer's employment agreement are described below.

In April 1999, we entered into an employment agreement with Dr. Rothblatt. This agreement was amended from time to time and we entered into an Amended and Restated Executive Employment Agreement with Dr. Rothblatt effective January 1, 2009 in order to clarify the effectiveness of certain prior amendments, and to make certain other immaterial amendments. This agreement was further amended effective January 1, 2015, to remove her entitlement to an annual grant of stock options based on a market capitalization growth formula and to provide flexibility for our company to grant her incentive-based compensation in a variety of forms in our Compensation Committee's discretion. The amendment also eliminated Dr. Rothblatt's right to an Internal Revenue Code Section 280G excise tax gross-up payment, among other changes.

Dr. Rothblatt's employment agreement provides for an initial five-year term, which is automatically extended for an additional year at the end of each year unless either party gives at least six months' notice of termination. If either party provided such a notice of termination, it would result in a four-year remaining term. We note that this rolling five-year term has no bearing on potential severance payments upon termination, which are described under Potential Payments Upon Termination or Change in Control.

Dr. Rothblatt's compensation in 2017 was paid pursuant to this employment agreement, which entitles her to a minimum base salary of $180,000, annual cash and long-term incentive compensation and participation in employee benefits generally available to other executives of our company. The level of Dr. Rothblatt's base salary is subject to annual review and increase by our Compensation Committee. Her annual salary was reviewed in early 2017, and beginning March 1, 2017, was set at $1,180,000. Her employment agreement also requires us to pay the cost of leasing, maintaining and insuring an automobile for Dr. Rothblatt.

Dr. Rothblatt's employment agreement prohibits her from engaging in activities competitive with us for five years following her last receipt of compensation from us. She is also subject to a permanent confidentiality obligation. For information regarding severance and change in control arrangements for Dr. Rothblatt, see the text following the Potential Payments Upon Termination or Change in Control table below.

We have entered into employment agreements with each of Messrs. Edgemond, Benkowitz and Mahon. The agreement for Mr. Mahon provides for an initial five-year term, which is automatically extended for an additional year at the end of each year. Either party may terminate the agreement a certain time period prior to an annual renewal, which would result in a four-year remaining term. The agreements for Messrs. Benkowitz and Edgemond provide an initial term of three years, following which the agreement continues from year-to-year for one-year terms unless either party provides written notice to terminate a certain time period prior to the end of the then-current term. Each employment agreement provides for an annual minimum base salary, which is subject to annual review and increase by our Compensation Committee. Annual salaries for each of these executives were

reviewed in early 2017, with raises becoming effective March 1, 2017. The following table outlines these details for each executive:

Under these agreements, each executive is eligible to participate in our broad-based employee benefit plans. In accordance with our executive automobile policy, we also pay the cost for leasing, maintaining and insuring an automobile for Messrs. Edgemond, Benkowitz and Mahon each receive a monthly car allowance of $1,000 per month.

Each of these employment agreements prohibits the executive from accepting employment, consultancy or any other business relationships with an entity that directly competes with us or from engaging in the solicitation of our employees on behalf of a competitor for a period of time following his last receipt of compensation from us (two years in the case of Mr. Mahon and one year in the case of Mr. Edgemond and Mr. Benkowitz). Each agreement includes an obligation of confidentiality for three years after termination of the executive's employment.

Messrs. Edgemond and Benkowitz are each party to a change in control severance agreement providing benefits in the event of his termination following a change in control of our company. In particular, these benefits include a cash severance payment equal to two times base salary, plus two times the highest of (i) the cash incentive award paid to the individual for the year immediately preceding the year in which the change in control occurs, (ii) the cash incentive award payable to the individual for the year immediately preceding the year in which the termination of employment occurs, or (iii) the individual's annual target cash incentive award. This cash severance would become payable in lieu of any severance payment under the respective employment agreements unless severance under the employment agreement would result in a greater benefit. The change in control severance agreement also provides for continuation of medical benefits for 24 months following termination, and outplacement benefits with a value of $10,000.

For further information regarding severance and change in control arrangements for these Named Executive Officers, see the text following the Potential Payments Upon Termination or Change in Control table below.

For 2014 and prior years, Dr. Rothblatt was eligible to receive an annual award of options to purchase a number of shares of common stock equal to one-eighteenth of one percent of the increase in our market capitalization, calculated using the average closing price for the month of December versus the average measured in December of the prior year. Through the end of 2014, all of Dr. Rothblatt's stock options were awarded pursuant to our EIP, have a term of ten years and are fully vested and exercisable on the date of grant. The stock options have an exercise price equal to the closing price on the Nasdaq on the date of grant. Effective January 1, 2015, this entitlement was eliminated from her employment agreement, and the issuance of awards under the EIP was discontinued.

As described in the section entitled Long-Term Incentive Award Compensation in the Compensation Discussion and Analysis above, in 2015 our Named Executive Officers (other than Dr. Rothblatt) were

granted STAP awards based on 2014 performance. The issuance of STAP awards was discontinued upon the approval of our 2015 SIP in June 2015. In 2017, our Named Executive Officers were granted stock options under our 2015 SIP.

These long-term incentive awards are granted annually, concurrently with the cash incentive award awards. The STAP awards convey the right to receive an amount in cash equal to the positive difference between the exercise price (which equals the closing price of our common stock on the date of grant) and the closing price of our common stock on the date of exercise. The fair value is based on the closing price of our common stock on the relevant grant date.

STAP awards granted to our Named Executive Officers in 2015 and stock options granted under the 2015 SIP in 2016 vest in one-fourth increments on the first four anniversaries of the date of grant, in each case subject to the Named Executive Officer's continued employment. Stock options granted under the 2015 SIP in 2017 vest in one-third increments on the first three anniversaries of the date of grant (in the case of stock options granted as a result of 2016 performance under our Company-Wide Milestone Program, and Milestone Performance Options granted with respect to 2017 performance, to the extent earned), or cliff vest on the third anniversary of the date of grant to the extent earned based on performance (in the case of Cash Profit Performance Options), in each case subject to the Named Executive Officer's continued employment. Each award has a ten-year term. For information regarding acceleration of vesting upon certain employment termination events, see the text following the Potential Payments Upon Termination or Change in Control table below.

The following table sets forth information regarding unexercised stock options or STAP awards held by each of our Named Executive Officers as of December 31, 2017.



				Number of Securities Underlying Unexercised Options or STAP Awards
									Option or STAP Award Exercise Price ($)		Option or STAP Award Expiration Date
Name and Grant Date	Award Type			(#) Exercisable		(#) Unexercisable			Option or STAP Award Exercise Price ($)		Option or STAP Award Expiration Date
Martine Rothblatt
12/31/2009		Stock Option	⁽¹⁾		430,244		—	—		52.65		12/31/2019
12/31/2010		Stock Option	⁽¹⁾		364,834		—	—		63.22		12/31/2020
12/31/2012		Stock Option	⁽¹⁾		55,488		—	—		53.42		12/31/2022
12/31/2013		Stock Option	⁽¹⁾⁽²⁾		1,000,000		—	—		113.08		12/31/2023
12/31/2014		Stock Option	⁽¹⁾⁽²⁾		723,869		—	—		129.49		12/31/2024
03/15/2016		Stock Option	⁽³⁾		73,500		220,500	—		120.26		03/15/2026
03/15/2017		Stock Option	⁽⁴⁾		—		240,000	—		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁵⁾		—		—	100,000		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁶⁾		—		150,288	—		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁶⁾		—		—	32,804		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁵⁾		—		—	244,122		146.03		03/15/2027
James Edgemond
01/14/2013		STAP Award	⁽⁷⁾		5,000		—	—		52.12		01/14/2023
03/14/2014		STAP Award	⁽³⁾		1,808		603	—		94.96		03/14/2024
03/13/2015		STAP Award	⁽³⁾		12,500		12,500	—		163.30		03/13/2025
03/13/2015		STAP Award	⁽³⁾		7,580		7,580	—		163.30		03/13/2025
03/15/2016		Stock Option	⁽³⁾		12,250		36,750	—		120.26		03/15/2026
03/15/2017		Stock Option	⁽⁴⁾		—		45,000	—		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁵⁾		—		—	18,750		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁶⁾		—		32,205	—		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁶⁾		—		—	7,029		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁵⁾		—		—	52,312		146.03		03/15/2027
Michael Benkowitz
04/04/2011		STAP Award	⁽³⁾		21,750		—	—		68.14		04/04/2021
03/15/2012		STAP Award	⁽³⁾		6,450		—	—		47.50		03/15/2022
01/02/2013		STAP Award	⁽⁸⁾		—		100,000	—		53.83		01/02/2023
03/15/2013		STAP Award	⁽³⁾		18,400		—	—		61.06		03/15/2023
03/14/2014		STAP Award	⁽³⁾		30,000		10,000	—		94.96		03/14/2024
03/13/2015		STAP Award	⁽³⁾		18,600		18,600	—		163.30		03/13/2025
03/15/2016		Stock Option	⁽³⁾		9,800		29,400	—		120.26		03/15/2026
06/24/2016		Stock Option	⁽³⁾		13,125		39,375	—		102.11		06/24/2026
03/15/2017		Stock Option	⁽⁴⁾		—		63,000	—		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁵⁾		—		—	26,250		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁶⁾		—		42,940	—		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁶⁾		—		—	9,372		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁵⁾		—		—	69,750		146.03		03/15/2027
Paul Mahon
03/15/2011		STAP Award	⁽³⁾		51,500		—	—		65.80		03/15/2021
03/15/2013		STAP Award	⁽³⁾		115,000		—	—		61.06		03/15/2023
03/14/2014		STAP Award	⁽³⁾		93,750		31,250	—		94.96		03/14/2024
03/13/2015		STAP Award	⁽³⁾		58,124		58,126	—		163.30		03/13/2025
03/15/2016		Stock Option	⁽³⁾		30,625		91,875	—		120.26		03/15/2026
03/15/2017		Stock Option	⁽⁴⁾		—		75,000	—		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁵⁾		—		—	31,250		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁶⁾		—		42,940	—		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁶⁾		—		—	9,372		146.03		03/15/2027
03/15/2017		Stock Option	⁽⁵⁾		—		—	69,750		146.03		03/15/2027

(2): These stock options have been transferred to trusts beneficially owned by Dr. Rothblatt and her spouse, for estate planning purposes.
(3): These stock options or STAP awards vest in one-fourth increments on each of the first four anniversaries of the date of grant.
(4): These stock options vest in one-third increments on each of the first three anniversaries of the date of grant.
(5): These stock options are subject to a three-year performance threshold tied to average cash profit margin. To the extent earned, these stock options vest at the end of the three-year performance period. Given performance to-date has fallen above target, the number of shares shown is at "maximum". The number of shares that are ultimately earned may be lower, depending on performance over the relevant three-year period.
(6): These stock options are subject to a one-year performance threshold tied to 2017 Company-Wide Milestone Performance. Once earned, shares vest in equal installments over a three-year period. The number of shares shown reflect the number of shares earned based on actual 2017 performance.
(7): One-time STAP award granted upon Mr. Edgemond's commencement of employment, which vested in full on February 28, 2015.
(8): Vested in full on January 2, 2018.

The following table shows (i) the number of shares of our common stock acquired upon exercise of stock options; and (ii) the number of STAP awards exercised by each of our Named Executive Officers during the year ended December 31, 2017.

The table below describes the present value of the accumulated benefit for our Named Executive Officers under the SERP.

In 2006, our Compensation Committee approved our SERP, which is a non-qualified supplemental defined benefit retirement plan for select key executives intended to enhance the long-term retention of individuals that have been and will continue to be vital to our success. Participants in the SERP generally must remain in the employ of our company or one of its affiliates until age 60 to receive a benefit except in the event of death, disability or a change in control of our company. If a participant terminates employment with us for any reason prior to age 60 (other than due to death or disability or following a change in control), no benefit will be paid. The benefit to be paid under the plan is based on when an executive commenced participation in the plan. In general, a participant will be eligible for an unreduced benefit under the plan after 15 years of service. Upon a change in control before a participant reaches age 60, he or she will immediately vest in and receive a prorated benefit based on years of service to date.

The SERP is administered by our Compensation Committee. Currently, our Named Executive Officers and four other members of senior management participate in the SERP. Each of our Named Executive Officers all eligible, upon retirement after the age of 60, to receive monthly payments equal to the monthly average of the total gross base salary received by the participant over his or her last 36 months of active employment (the Final Average Compensation), reduced by the participant's estimated social security benefit (determined as provided under the SERP), for the remainder of the participant's life (the aggregate amount of such payments, the Normal Retirement Benefit), commencing on the first day of the sixth month after retirement. For executives who began participating in the plan after July 1, 2006, the retirement benefit is generally calculated as 100% of the final three-year average gross base salary reduced by the estimated social security benefit they would receive in retirement, multiplied by a fraction (not to exceed 1) the numerator of which is their years of service and the denominator of which is 15 (the Normal Retirement Benefit). This means that for participants who have less than 15 years of service with us, the retirement benefit is prorated by the number of years of actual service divided by 15 years. By age 60, all of the current participants will have had 15 years of service if they remain employed by us. In the event of termination of employment due to disability prior to the age of 60 or death prior to retirement, a participant or the participant's beneficiary, as applicable, will be entitled to a percentage of the Normal Retirement Benefit, as determined under the SERP (the aggregate amount of such payments referred to as the Disability Retirement Benefit), commencing on the first day of the sixth month after termination of employment in the event of a Disability and as soon as administratively practicable in the event of death. All of our Named Executive Officers have elected to receive their benefit in the form of a lump sum, although they were also offered a choice of a single life annuity or an actuarially equivalent joint or survivor annuity.

In the event of a change in control, as defined in the SERP, a participant who is actively employed on the date of the change in control will be entitled to a lump sum payment equal to the actuarial equivalent present value of a monthly single life annuity equal to (1) the participant's Final Average

Compensation, reduced by the participant's estimated future social security benefit (determined as provided under the SERP), multiplied by (2) a fraction (no greater than one), the numerator of which equals the participant's years of service and the denominator of which equals 15, to be paid as soon as administratively practicable following the change in control. In the event that a participant is entitled to a Normal Retirement Benefit or Disability Retirement Benefit at the time of a change in control, all such payments (or any remaining payments, with respect to any participant who is receiving payments under the SERP at the time of the change in control) will be made in a lump sum as soon as administratively practicable following such change in control.

Participants in the SERP will be prohibited from competing with us or soliciting its employees for a period of twelve months following his or her termination of employment (or, if earlier upon attainment of age 65). Violation of this covenant will result in forfeiture of all benefits under the SERP.

In December 2007, our Compensation Committee adopted the United Therapeutics Corporation Supplemental Executive Retirement Plan Rabbi Trust Document (Rabbi Trust Document), providing for the establishment of a trust (Rabbi Trust), the assets of which will be contributed by us and used to pay benefits under the SERP. The Rabbi Trust Document was entered into between our company and Wilmington Trust Company, which will serve as trustee of the Rabbi Trust. The Rabbi Trust is irrevocable, and SERP participants will have no preferred claim on, nor any beneficial ownership interest in, any assets of the Rabbi Trust.

Currently, the Rabbi Trust does not contain any assets. Generally, we may contribute additional assets to the Rabbi Trust at our sole discretion. However, pursuant to the terms of the Rabbi Trust Document, within five days following the occurrence of a potential change in control (as defined in the Rabbi Trust Document), or if earlier, at least five days prior to the occurrence of a change in control (as defined in the Rabbi Trust Document), we will be obligated to make an irrevocable contribution to the Rabbi Trust in an amount sufficient to pay each SERP participant or beneficiary the benefits to which they would be entitled pursuant to the terms of the SERP on the date on which the change in control occurred. The Rabbi Trust will not terminate until the date on which SERP participants or their beneficiaries are no longer entitled to benefits pursuant to the terms of the SERP.

Each of our Named Executive Officers is eligible to receive certain payments and benefits if his or her employment is involuntarily terminated without "Cause", terminated by the executive for "Good Reason", terminated by the executive voluntarily with continued status as a "Senior Advisor" to us, terminated due to disability or death, or terminated in connection with a "Change in Control" of our company in accordance with the applicable terms of their respective employment agreements, change in control severance agreements, the SERP, our equity compensation plans (the EIP and 2015 SIP) and related stock option agreements, and the STAP and related award agreements, as reported in the Potential Payments Upon Termination or Change in Control table below and described in the narrative table that follows. The summary of these benefits is qualified in its entirety by the specific language of the various agreements and plans that have been filed with the SEC. The amounts shown in the Potential Payments Upon Termination or Change in Control table below are estimates of the value of these payments and benefits, assuming that such termination or triggering event was effective as of December 31, 2017 (except as otherwise noted below with respect to those Named Executive Officers who terminated during the year). The actual compensation to be paid to a Named Executive Officer can only be determined at the time such Named Executive Officer's employment is terminated and may vary based on factors such as the timing during the year of any such event, our stock price, the executive officer's age, and any changes to our benefit arrangements and policies. In addition to the benefits described below, our Named Executive Officers will be eligible to receive any benefits accrued under our broad-based benefit plans, such as distributions under life insurance and disability benefit plans.

Executive Benefits and Payments Upon Separation	Involuntary Termination Without Cause/ Resignation for Good Reason/ Resignation While Continuing as Senior Advisor⁽¹⁾			Disability		Death		Termination upon a Change in Control		Change In Control without Termination of Employment

Martine Rothblatt
Salary and cash incentive	$	7,867,232		$	1,180,000	$	1,180,000	$	7,867,232	$	—
Stock option vesting acceleration⁽²⁾		7,227,160			—		—		7,227,160		7,227,160
Supplemental Executive Retirement Plan		16,436,226	⁽³⁾		16,155,542		11,039,012		16,436,226		16,436,226
Health and other benefits⁽⁴⁾		122,728			—		—		122,728		—

Total	$	31,653,346		$	17,335,542	$	12,219,012	$	31,653,346	$	23,663,386



James Edgemond
Salary and cash incentive	$	123,288		$	—	$	—	$	2,187,500	$	—
STAP award and stock option vesting acceleration⁽²⁾		—			1,272,400		1,272,400		1,272,400		1,272,400
Supplemental Executive Retirement Plan.		—			3,082,628		2,175,349		1,794,050		1,794,050
Health and other benefits⁽⁵⁾		—			—		—		48,719		—

Total	$	123,288		$	4,355,028	$	3,447,749	$	5,302,669	$	3,066,450



Michael Benkowitz
Salary and cash incentive	$	1,113,699		$	—	$	—	$	2,700,000	$	—
STAP award and stock option vesting acceleration⁽²⁾		—			12,866,215		12,866,215		12,866,215		12,866,215
Supplemental Executive Retirement Plan.		—			3,457,676		2,464,759		2,177,236		2,177,236
Health and other benefits⁽⁵⁾		—			—		—		48,719		—

Total	$	1,113,699		$	16,323,891	$	15,330,974	$	17,792,170	$	15,043,451



Paul Mahon
Salary and cash incentive	$	2,549,549		$	—	$	—	$	2,549,549	$	—
STAP award and stock option vesting acceleration⁽²⁾		4,537,876			4,537,876		4,537,876		4,537,876		4,537,876
Supplemental Executive Retirement Plan		—			10,226,799		7,039,354		9,853,466		9,853,466

Total	$	7,087,425		$	14,764,675	$	11,577,230	$	16,940,891	$	14,391,342

(1): Benefits upon termination while continuing as a senior advisor are applicable only to employment agreements with Dr. Rothblatt and Mr. Mahon.
(2): The value shown is based on the positive difference between the aggregate exercise price of all accelerated stock options and/or STAP awards and the aggregate market value of the underlying shares calculated based on the closing market price of our common stock on December 31, 2017, $147.95. Per the terms of awards containing performance-vesting criteria, acceleration will result in the vesting of the "target" number of shares.
(3): Dr. Rothblatt's employment agreement provides for SERP benefits under her employment agreement upon reaching age 65, including three additional years of service. Given Dr. Rothblatt has attained retirement age and has already reached the maximum number of years of service under the SERP, this additional benefit is no longer applicable. As a result, the value included in this table represents the normal benefits Dr. Rothblatt would receive upon retirement, in accordance with the terms of the SERP.
(4): Represents the estimated value of continued health care benefits for a three-year period after termination, outplacement services for 12 months and the fair value of one currently leased vehicle.
(5): Represents the estimated value of continued health care benefits for a two-year period after termination and outplacement services equal to $10,000.

Provision	Terms Applicable to Chairman and CEO	Terms Applicable to Mr. Mahon

Payments Upon Involuntary Termination without Cause, or Resignation for Good Reason, or Resignation while Continuing as Senior Advisor	• Lump sum prorated cash incentive and incentive payment^* • Lump sum payment equal to 3.0 times base salary + 3.0 times annual cash incentive award^* • Continuation of health care benefits for 36 months, outplacement services for 12 months and the transfer of one currently leased vehicle • Immediate vesting of unvested stock options	• Lump sum payment equal to 2.0 times: (i) current base salary; plus (ii) annual cash incentive award^* • Immediate vesting of unvested stock options and STAP awards
Payments Upon Disability	• Continued payment of current base salary through the end of the calendar year following such disability • Acceleration of SERP benefits • Immediate vesting of unvested stock options	• Immediate vesting of unvested stock options and STAP awards • Acceleration of SERP benefits
Payments Upon Death	• Continued payment of current base salary through the end of the calendar year following such death to Executive's legal representatives • Acceleration of SERP benefits • Immediate vesting of unvested stock options	• Immediate vesting of unvested stock options and STAP awards • Acceleration of SERP benefits
Payments Upon Change in Control without Termination	• Acceleration of SERP benefits • Immediate vesting of unvested stock options (if not assumed)	• Acceleration of SERP benefits • Immediate vesting of unvested stock options and STAP awards (if not assumed)
Payments Upon Termination Following Change in Control	• Same as Payments Upon Involuntary Termination, etc., except that payment of SERP benefits occurs immediately, and is calculated as described above under Supplemental Executive Retirement Plan	• Same as Payments Upon Involuntary Termination, etc. • Acceleration of SERP benefits

Provision		Terms Applicable to Mr. Edgemond and Mr. Benkowitz

Payments Upon Involuntary Termination without Cause		• Lump sum payment equal to base salary through the remainder of the agreement term
Payments Upon Disability		• Continued payment of current base salary through date of termination • Immediate vesting of unvested stock options and STAP awards • Acceleration of SERP benefits
Payments Upon Death		• Immediate vesting of unvested stock options and STAP awards • Acceleration of SERP benefits
Payments Upon Change in Control without Termination		• Acceleration of SERP benefits • Immediate vesting of unvested stock options and STAP awards (if not assumed)
Payments Upon Termination Following Change in Control		• Payment of a lump sum cash amount equal to 2.0 times the sum of (x) base salary plus (y) the highest of (i) the cash incentive paid to the individual for the year immediately preceding the year in which the change in control occurs, (ii) the cash incentive award payable to the individual for the year immediately preceding the year in which the termination of employment occurs, or (iii) the individual's annual target cash incentive award. • Immediate vesting of unvested stock options and STAP awards • Acceleration of SERP benefits • Continuation of medical benefits for 24 months • Outplacement benefits with a value of $10,000

As used in the tables above, the following terms are generally defined as follows:

Change in Control: Transfer of control of our company (generally, as a result of an acquisition, merger, hostile takeover or any other reason).

As required by Section 953(b) of the Dodd-Frank Wall Street Reform and Consumer Protection Act and Item 402(u) of Regulation S-K, we are required to disclose the ratio of the 2017 compensation of our principal executive officer to that of our median compensated employee.

During 2017, the principal executive officer of United Therapeutics was our Chief Executive Officer, Dr. Martine Rothblatt. For purposes of this pay ratio disclosure, the 2017 annual total compensation for Dr. Rothblatt was $37,148,572, and for our median employee, identified as discussed below, was $182,747, resulting in a pay ratio of approximately 203:1. The annual total compensation of our CEO for purposes of this disclosure differs from the total annual compensation reflected in the Summary Compensation Table because we included the value of employer paid non-discriminatory health and welfare benefits, which are not required to be disclosed in the Summary Compensation Table, but which we include here to give a more complete picture of our median employee's total rewards compensation.

As noted above under Supplementary 2017 Summary Compensation Table, the 2017 annual total compensation of Dr. Rothblatt as reported in the Summary Compensation Table and as used in determining the pay ratio disclosed above, includes the value of equity awards granted to Dr. Rothblatt in 2017, based on 2016 performance. In order to provide a more complete depiction of our pay ratio for 2017, a supplemental pay ratio was calculated using Dr. Rothblatt's pro forma 2017 compensation, as disclosed in the Supplementary 2017 Compensation Table, plus the value of employer paid non-discriminatory health and welfare benefits, totaling $17,948,772. The ratio of this measure to the compensation of the median employee, including the value of employer paid non-discriminatory health and welfare benefits as described above, was approximately 98:1.

In accordance with Item 402(u) of Regulation S-K, we identified our employee population as of October 1, 2017 and determined the median employee by (i) aggregating for each applicable employee (A) annual base salary determined as of October 1, 2017 for salaried employees (or hourly rate as of the same date, multiplied by estimated hours worked in 2017, for hourly employees), (B) and the target cash incentive, commissions, and overtime earned in 2017, and (ii) ranking this compensation measure for our employees from lowest to highest. This calculation was performed for all employees except as disclosed in the following paragraph, excluding Dr. Rothblatt, whether employed on a full-time, part-time, or seasonal basis.

For purposes of identifying the median employee, all employees located outside of the United States, totaling 17 individuals, were excluded from the determination of the median employee pursuant to the so-called de minimis exemption, which permits us to exclude foreign employees, up to 5% of our total employee population of 785, on a whole-country basis. As of October 1, 2017, these employees were located in the following countries: Canada (2), China (1), Germany (2) and United Kingdom (12). Applying this de minimis exemption, as of October 1, 2017, we considered a total of 768 US-based employees (excluding our CEO) and no employees located outside of the US. Irrespective of the de minimis exemption, on this same date we had 768 US-based employees and no employees located outside of the United States for purposes of our pay ratio calculation.

The pay ratio reported above is a reasonable estimate calculated in a manner consistent with SEC rules based on our internal records and the methodology described above. The SEC rules for identifying the median compensated employee and calculating the pay ratio based on that employee's annual total compensation, allows companies to adopt a variety of methodologies, to apply certain exclusions, and to make reasonable estimates and assumptions that reflect their employee populations and compensation practices. Therefore, the pay ratio reported by other companies may not be comparable to the pay ratio reported above, as other companies have different employee populations and compensation practices and may utilize different methodologies, exclusions, estimates and assumptions in calculating their own pay ratios.

PROPOSAL NO. 3
APPROVAL OF THE AMENDMENT AND RESTATEMENT OF THE UNITED THERAPEUTICS CORPORATION 2015 STOCK INCENTIVE PLAN

We are asking our shareholders to approve an amendment and restatement (the 2018 Restatement) of the United Therapeutics Corporation 2015 Stock Incentive Plan (the Plan). On April 29, 2015, our Board of Directors unanimously adopted and approved the United Therapeutics Corporation 2015 Stock Incentive Plan (the Plan). Our shareholders subsequently approved the Plan at our 2015 annual meeting of shareholders.

Our Board of Directors adopted and approved the Plan to stimulate the efforts of non-employee directors, officers, employees and other service providers, in each case who are selected to be participants in the Plan, by heightening the desire of such persons to continue working toward and contributing to the success and progress of our company. The Plan allows grants of stock options, stock appreciation rights, restricted stock, restricted stock units and stock awards, any of which may be performance-based, and for cash incentives.

We believe that a comprehensive equity compensation program serves as a necessary and powerful tool to attract, retain and incentivize individuals essential to our financial success and accordingly benefits all of our stockholders by allowing us to retain individuals who are expected to make significant contributions to the creation of stockholder value.

In addition to a number of technical and clarifying changes, the 2018 Restatement makes three key changes to the Plan:

Our Board of Directors recommends that our shareholders approve the 2018 Restatement of the Plan. First, we offer equity-based compensation to virtually all of our full-time employees, executive officers and non-employee directors. Like other similarly-situated biotech and pharmaceutical companies, many of which we compete with for talent, equity is an important part of our compensation program. Our ability to continue granting equity-based awards is crucial to ensure that we can attract, motivate and reward key talent so that we can continue to deliver the exceptional type of performance highlighted in the Compensation Discussion and Analysis. At the current burn rate for equity awards, we expect that the initial limit of 6,150,000 shares available for issuance under the Plan will be used up prior to the annual issuance of awards to Named Executive Officers and other employees in March 2019. If the 2018 Restatement is not approved, we will need to grant cash-based or other awards in order to remain competitive; these awards may not align the interests of our key employees and non-employee directors as closely with those of our shareholders as equity awards. In addition, the use of cash resources to deliver competitive pay would divert cash from use in running other aspects of our business and investing in future product development.

Second, the 2018 Restatement specifies an aggregate limit on cash and equity compensation that may be annually provided to our non-employee directors. The Plan's previous limit applied solely to the issuance of equity awards and was stated as awards with respect to a specified number of shares (rather than a dollar value).

Our company and our Board of Directors have designed the Plan to include a number of provisions that we believe promote best practices by reinforcing the alignment between equity compensation arrangements for non-employee directors, officers, employees and other service providers and shareholders' interests. These provisions include, but are not limited to:

The following table includes information regarding all of our outstanding equity awards (under all of our equity-based compensation plans under which shares of common stock may be issued, other than our Employee Stock Purchase Plan) and shares available for future awards under the Plan as of April 10, 2018:

The potential dilution from the additional 2,900,000 shares to be made available for issuance under the Plan is approximately 6.7% (calculated as the additional shares requested divided by shares outstanding as of April 10, 2018). Our Board of Directors has considered this potential dilution level in the context of competitive data from our peer group, and believes that the resulting dilution levels would be within normal competitive ranges. Actual dilution from the Plan will depend on several factors, including the type of awards made under the Plan. This is because the Plan uses a fungible share design, under which each share issued pursuant to a stock option or stock appreciation right will reduce the number of shares available under the Plan by one share, and each share issued pursuant to other awards will reduce the number of shares available by 2.14 shares. If all of the shares available under the Plan were to be granted in the form of restricted stock units, the total potential dilution from the Plan would be approximately 3.1% as of April 10, 2018 (calculated as the shares available under the Plan divided first by 2.14 and then by the total shares outstanding as of April 10, 2018).

We manage our long-term dilution goal by limiting the number of shares subject to equity awards that we grant annually, commonly referred to as burn rate. Burn rate shows how rapidly a company is depleting its shares reserved for equity compensation plans, and is defined as the number of shares granted under our equity incentive plans divided by the weighted average number of common shares outstanding at the end of the year. We have calculated the burn rate under the Plan for the past three years, as set forth in the following table:

An additional metric that we use to measure the cumulative impact of our equity program is overhang (the number of shares subject to equity awards outstanding but not exercised or settled, plus the number of shares available to be granted, divided by the sum of the total number of shares our common stock outstanding, plus the number of shares subject to equity awards outstanding but not exercised or settled, plus the number of shares available to be granted). If the Plan is approved, our overhang calculated on this basis would increase to approximately 20.0%, and then would be expected to decline as awards are exercised and/or become vested.

When considering the Plan, our Board of Directors also reviewed, among other things, projected future share usage and projected future forfeitures. The projected future usage of shares for long-term incentive awards under the Plan was reviewed under scenarios based on a variety of assumptions. Depending on assumptions, the 2,900,000 additional shares to be made available under the Plan is expected to satisfy our equity compensation needs for approximately 2-3 years of similar levels of awards based on current utilization levels. Our Board of Directors is committed to effectively managing the number of shares reserved for issuance under the Plan while minimizing shareholder dilution.

The following summary of the material terms of the Plan is qualified in its entirety by reference to the complete statement of the Plan, which is set forth in Annex A to this Proxy Statement.

The Plan will be administered by our Compensation Committee. Subject to the express provisions of the Plan, the administrator is authorized and empowered to do all things that it determines to be necessary or appropriate in connection with the administration of the Plan. All decisions, determinations and interpretations by our Compensation Committee regarding the Plan and awards granted under the Plan will be final and binding on all participants and other persons holding or claiming rights under the Plan or an award under the Plan. Our Compensation Committee may authorize one or more officers of our company to perform any or all things that the administrator is authorized and empowered to do or perform under the Plan. Our Compensation Committee may delegate any or all aspects of the day-to-day administration of the Plan to one or more officers or employees of our company or any subsidiary, and/or to one or more agents.

Any person who is a current or prospective officer or employee of our company or of any subsidiary may be eligible for selection by the administrator for the grant of awards under the Plan. In addition, non-employee directors and any service providers who have been retained to provide consulting, advisory or other services to our company or to any subsidiary may be eligible for the grant of awards under the Plan. Options intended to qualify as "incentive stock options" (ISOs) within the meaning of Section 422 of the Code may be granted only to employees of our company or any subsidiary. Approximately 785 officers and employees and 9 non-employee directors currently qualify to participate in the Plan.

Subject to changes in our capitalization, the aggregate number of shares of our common stock issuable pursuant to all awards under the Plan will not exceed 9,050,000 shares; provided that any shares granted under options or stock appreciation rights will be counted against this limit on a one-for-one basis and any shares granted as awards other than options or stock appreciation rights will be counted against this limit as 2.14 shares for every one (1) share subject to such award. The shares issued pursuant to awards granted under the Plan may be shares that are authorized and unissued or issued shares that were reacquired by our company, including shares purchased in the open market.

For purposes of determining the share limits described in the paragraph above, the aggregate number of shares issued under the Plan at any time will equal only the number of shares actually issued upon exercise or settlement of an award. Notwithstanding the foregoing, shares subject to an award under the Plan may not again be made available for issuance under the Plan if such shares are: (i) shares that were subject to a stock-settled stock appreciation right and were not issued upon the net settlement or net exercise of such stock appreciation right; (ii) shares used to pay the exercise price of an option; (iii) shares delivered to or withheld by our company to pay the withholding taxes related to an award; or (iv) shares repurchased on the open market with the proceeds of an option exercise.

Shares subject to awards that have been canceled, expired, forfeited or otherwise not issued under an award and shares subject to awards settled in cash will not count as shares issued under the Plan.

Subject to certain adjustments, the aggregate number of shares subject to awards granted under the Plan during any calendar year to any one participant will not exceed 1,000,000 and the aggregate number of shares that may be issued pursuant to the exercise of ISOs granted under the Plan will not

exceed 9,050,000. The maximum amount payable pursuant to that portion of a cash incentive award granted in any calendar year to any participant under the Plan will not exceed $5 million.

In addition, the aggregate dollar value of awards (based on the aggregate accounting value on the date of grant) granted pursuant to the Plan during any calendar year to any non-employee director may not exceed $400,000 for annual equity grants (plus, for the year an individual first becomes a non-employee director (x) an initial equity grant valued at $400,000, plus (y) a pro-rata portion of the $400,000 annual equity-based award value based on the number of months remaining in the Board of Directors service year at the date of grant). The annual equity award may be payable in options, restricted stock units, or a combination, as elected by the non-employee director. The Plan further provides that the cash compensation paid or payable by the Company to a non-employee director with respect to any calendar year may not exceed $60,000 (with additional cash compensation of $35,000 for the lead independent director, $25,000 for each committee chairmanship, and $15,000 for each other committee membership), plus a pro-rated portion of the aggregate cash compensation for the roles in which the Nonemployee Director serves for the year an individual first becomes a non-employee director.

The administrator will establish the exercise price per share under each option, which, other than in the event of options granted in connection with a merger or other acquisition, will not be less than the fair market value (or 110% of the fair market value in the case of ISOs granted to individuals who own more than 10% of our common stock) of a share on the date the option is granted. The administrator will establish the term of each option, which in no case may exceed a period of ten (10) years from the date of grant (or five (5) years in the case of ISOs granted to individuals who own more than 10% of our common stock). Options granted under the Plan may either be ISOs or options which are not intended to qualify as ISOs, or nonqualified stock options (NQSOs). Unless the administrator determines otherwise; (i) upon termination of employment other than due to death, disability or termination for cause, participants may continue to exercise their options for ninety (90) days (or until the expiration date of the option, if earlier) to the extent that they were exercisable upon the date of termination; (ii) upon death or disability, options become fully vested and remain exercisable for one (1) year (or until the expiration date of the option, if earlier) following such event; and (iii) upon termination of employment for cause, all options are forfeited. Stock options may not include any "reload" feature. In no event shall any stock option fully vest before the first anniversary of the date of grant; provided that, if so determined by the administrator, an option may fully vest before such anniversary in the event of the Participant's death or disability or a change in control of our company.

A stock appreciation right provides the right to receive the monetary equivalent of the increase in value of a specified number of the shares over a specified period of time after the right is granted. Stock appreciation rights may be granted to participants either in tandem with or as a component of other awards granted under the Plan (tandem SARs) or not in conjunction with other awards (freestanding SARs). All freestanding SARs will be granted subject to the same terms and conditions applicable to options as set forth above and in the Plan, and all tandem SARs will have the same exercise price, vesting, exercisability, forfeiture and termination provisions as the award to which they relate.

Restricted stock is an award or issuance of shares the grant, issuance, retention, vesting and/or transferability of which is subject during specified periods of time to such conditions (including

continued employment or performance conditions) and terms as the administrator deems appropriate. Restricted stock units are awards denominated in units of shares under which the issuance of shares is subject to such conditions (including continued employment or performance conditions) and terms as the administrator deems appropriate. Notwithstanding the satisfaction of any performance goals, the number of shares granted, issued, retainable and/or vested under a restricted stock award or restricted stock units because of either financial performance or personal performance evaluations may be reduced, but not increased, by the administrator based on such further consideration as the administrator may determine.

In no event shall any restricted stock or restricted stock units fully vest before the first anniversary of the date of grant; provided that, if so determined by the administrator, restricted stock or restricted stock units may fully vest before such anniversary in the event of the Participant's death or disability or a change in control of our company. Unless the administrator determines otherwise, (i) upon termination of employment for any reason other than death or disability, all restricted stock and restricted stock units still subject to restrictions as of the date of termination will be forfeited, and (ii) upon death or disability, the restrictions remaining on a participant's restricted stock and restricted stock units will lapse.

Unless otherwise determined by the administrator, participants holding shares of restricted stock granted under the Plan may exercise full voting rights with respect to those shares during the period of restriction, and participants will have no voting rights with respect to shares underlying restricted stock units unless and until such shares are reflected as issued and outstanding shares in our stock ledger. Participants in whose name restricted stock is granted will be entitled to receive all dividends and other distributions paid with respect to those shares, unless determined otherwise by the administrator. Participants will be entitled to receive dividends or dividend equivalents with respect to shares underlying restricted stock units only to the extent provided by the administrator. However, in no event will dividends, distributions or dividend equivalents be payable with respect to unvested or unearned awards that are subject to performance criteria until such awards vest.

The administrator may grant stock awards under the Plan, which will be subject to the terms and conditions determined by the administrator. Participants will have all voting, dividend, liquidation and other rights with respect to shares underlying a stock award, subject to any restrictions on transfer determined by the administrator. In no event shall any stock award fully vest before the first anniversary of the date of grant; provided that, if so determined by the administrator, a stock award may fully vest before such anniversary in the event of the Participant's death or disability or a change in control.

Each cash incentive award will confer upon the participant the opportunity to earn a future payment tied to the level of achievement with respect to one or more performance criteria established for a performance period of not less than one (1) year. The administrator will establish the performance criteria and level of achievement of these criteria that will determine the target and maximum amount payable under a cash incentive award, which criteria may be based on financial performance and/or personal performance evaluations. Notwithstanding the satisfaction of any performance goals, the amount paid under a cash incentive award because of either financial performance or personal performance evaluations may be reduced, but not increased, by the administrator based on such further consideration as the administrator may determine.

Unless otherwise determined by the administrator, (i) if our Chairman and Chief Executive Officer or any other person designated by the administrator reasonably believes that a participant may have committed an act of misconduct (as defined in the Plan), then the participant's rights to exercise any option, vest in any award and/or receive payment for or shares in settlement of an award may be suspended pending a determination of whether an act of misconduct has been committed; and (ii) if the administrator, our Chairman and Chief Executive Officer or any other person designated by the administrator determines that a participant has committed an act of misconduct, then the participant (a) may not exercise any option or stock appreciation right, vest in, have restrictions on an award lapse or otherwise receive payment of an award; (b) will forfeit all outstanding awards; and (c) may be required, at the discretion of the committee, to return or repay to our company any then-unvested shares previously issued under the Plan.

Our Board of Directors may amend, alter or discontinue the Plan, and the administrator may amend or alter any agreement or other document evidencing an award made under the Plan, except no such amendment may, without the approval of the shareholders of our company: (i) increase the maximum number of shares for which awards may be granted under the Plan; (ii) reduce the minimum price set forth in the Plan at which options or stock appreciation rights may be granted; (iii) reduce the exercise price of outstanding options or stock appreciation rights; (iv) extend the term of the Plan, (v) change the class of persons eligible to be participants; (vi) otherwise amend the Plan in any manner requiring shareholder approval by law or under Nasdaq listing requirements (or the listing requirements of any successor exchange that is the primary stock exchange for trading of our shares); or (vii) increase the individual maximum limits set forth in the Plan.

No amendment or alteration to the Plan or an award or award agreement may be made that would impair the rights of the holder of an award without such holder's consent, provided that no such consent will be required if the administrator determines in its sole discretion and prior to the date of any change in control that such amendment or alteration either is required or advisable in order for our company, the Plan or the award to satisfy any law or regulation or to meet the requirements of or avoid adverse financial accounting consequences under any accounting standard. In addition, the Plan may not be amended in any way that causes the Plan to fail to comply with or be exempt from Section 409A of the Code, unless our Board expressly determines to amend the Plan to be subject to Section 409A of the Code.

The administrator may determine the effect of a change in control (as defined in the Plan) on outstanding awards in a manner that is fair and equitable to participants (as determined by the administrator in its reasonable discretion). These effects, which need not be the same for all participants, may include, but are not limited to (i) substituting for the shares subject to an outstanding award or portion thereof the stock or securities of the surviving corporation or any successor corporation, in which event the aggregate exercise price of the award will remain the same; and/or (ii) converting any outstanding award or portion thereof into a right to receive cash or other property following the consummation of the change in control in an amount equal to the value of consideration to be received for one share of our common stock in connection with such transaction less the purchase or exercise price of the shares subject to the award, multiplied by the number of shares subject to the award or portion thereof.

The number and kind of shares available for issuance under the Plan, and the number and kind of shares subject to the individual and ISO limits set forth under the Plan, will be equitably adjusted by the administrator to reflect any reorganization, reclassification, combination of shares, stock split, reverse stock split, spin-off, dividend or distribution of securities, property or cash (other than regular, quarterly cash dividends), or any other event or transaction that affects the number or kind of shares of our company outstanding. The terms of any outstanding award will also be equitably adjusted by the administrator as to price, number or kind of shares subject to such award and other terms to reflect the foregoing events, which adjustments need not be uniform as between different awards or different types of awards.

In the event there is a change in the number or kind of outstanding shares under the Plan as a result of a change of control, other merger, consolidation or otherwise, then the administrator will determine the appropriate and equitable adjustment to be effected. In addition, in the event of such a change, the administrator may accelerate the time or times at which any award may be exercised and may provide for cancellation of such accelerated awards that are not exercised within a time prescribed by the administrator in its sole discretion.

Unless the administrator determines otherwise, awards may not be sold, transferred, pledged, assigned, or otherwise alienated or hypothecated by a participant other than by will or the laws of descent and distribution, and each option or stock appreciation right may be exercisable only by the participant during his or her lifetime. To the extent permitted by the administrator, the person to whom an award is initially granted may make certain limited transfers to certain family members, family trusts, or family partnerships.

The Plan was initially was adopted by our Board on April 29, 2015 and approved by our shareholders at the 2015 annual meeting of shareholders. The 2018 Restatement was adopted on by our Board on April 25, 2018 and will become effective upon approval by our shareholders at the 2018 annual meeting. The Plan will remain available for the grant of awards until June 26, 2028.

The following tax discussion is a general summary as of the date of this Proxy Statement of the U.S. federal income tax consequences to our company and the participants in the Plan. The discussion is intended solely for general information and does not make specific representations to any participant. The discussion does not address state, local or foreign income tax rules or other U.S. tax provisions, such as estate or gift taxes. A recipient's particular situation may be such that some variation of the basic rules is applicable to him or her. In addition, the federal income tax laws and regulations frequently have been revised and may be changed again at any time. Therefore, each recipient is urged to consult a tax advisor before exercising any award or before disposing of any shares acquired under the Plan both with respect to federal income tax consequences as well as any foreign, state or local tax consequences.

ISOs and NQSOs are treated differently for federal income tax purposes. ISOs are intended to comply with the requirements of Section 422 of the Code. NQSOs need not comply with such requirements.

An optionee is not taxed on the grant or exercise of an ISO. The difference between the exercise price and the fair market value of the shares on the exercise date will, however, be a preference item for purposes of the alternative minimum tax. If an optionee holds the shares acquired upon exercise of an ISO until the later of two years following the option grant date and one year following exercise, the optionee's gain, if any, upon a subsequent disposition of such shares is long term capital gain. The measure of the gain is the difference between the proceeds received on disposition and the optionee's basis in the shares (which generally equals the exercise price). If an optionee disposes of stock acquired pursuant to exercise of an ISO before satisfying these holding periods, the optionee will recognize ordinary income in the year of disposition an amount equal to the excess of the fair market value of the shares at the time of exercise (or, if less, the amount realized on the disposition of the shares), over the exercise price paid for the shares, and capital gain or loss for any other difference between the sale price and the exercise price. Our company is not entitled to an income tax deduction on the grant or exercise of an ISO or on the optionee's disposition of the shares after satisfying the holding period requirement described above. If the holding periods are not satisfied, our company will be entitled to a deduction in the year the optionee disposes of the shares in an amount equal to the ordinary income recognized by the optionee.

In order for an option to qualify for ISO tax treatment, the grant of the option must satisfy various other conditions more fully described in the Code. We do not guarantee that any option will qualify for ISO tax treatment even if the option is intended to qualify for such treatment. In the event an option intended to be an ISO fails to so qualify, it will be taxed as an NQSO described below.

An optionee is not taxed on the grant of an NQSO. On exercise, the optionee recognizes ordinary income equal to the difference between the exercise price and the fair market value of the shares acquired on the date of exercise. Our company is entitled to an income tax deduction in the year of exercise in the amount recognized by the optionee as ordinary income. The optionee's gain (or loss) on subsequent disposition of the shares is long-term capital gain (or loss) if the shares are held for at least one year following exercise, and otherwise is short-term capital gain (or loss). Our company does not receive a deduction for any such capital gain.

Generally, the recipient of a freestanding SAR will not recognize any taxable income at the time the freestanding SAR is granted. If the freestanding SAR is settled in cash, the cash will be taxable as ordinary income to the recipient at the time that it is received. If the freestanding SAR is settled in shares, the recipient will recognize ordinary income equal to the excess of the fair market value of the shares on the day they are received over any amounts paid by the recipient for the shares.

With respect to tandem SARs, if a holder elects to surrender the underlying option in exchange for cash or stock equal to the appreciation inherent in the underlying option, the tax consequences to the employee will be the same as discussed above relating to freestanding SARs. If the employee elects to exercise the underlying option, the holder will be taxed at the time of exercise as if he or she had exercised an NQSO (discussed above).

Our company generally is entitled to a deduction with respect to a SAR at the same time the recipient recognizes ordinary income with respect thereto.

Grantees of restricted stock or restricted stock units do not recognize income at the time of the grant. When the award vests or is paid, grantees generally recognize ordinary income in an amount equal to the fair market value of the stock or units at such time, and our company will receive a corresponding deduction. Dividends (if any) paid with respect to unvested shares of restricted stock generally will be taxable as ordinary income to the participant at the time the dividends are received.

Subject to Section 162(m) of the Code, our company generally will be entitled to a deduction with respect to restricted stock and restricted stock units at the same time the recipient recognizes ordinary income with respect thereto.

Grantees of stock awards generally are required to recognize ordinary income in an amount equal to the excess of the fair market value of the shares on the date the shares are granted over the purchase price (if any) paid for the shares. Subject to Section 162(m) of the Code, our company generally will be entitled to a deduction with respect to stock awards at the same time the recipient recognizes ordinary income with respect thereto.

A participant will have taxable income at the time a cash incentive award is paid or, if the participant has timely elected deferral to a later date, such later date. At that time, the participant will recognize ordinary income equal to the value of the amount then payable and, subject to Section 162(m) of the Code, our company will be entitled to a corresponding deduction.

Our company generally will be entitled to a deduction for federal income tax purposes as described above with respect to each type of award. However, pursuant to the Jobs and Tax Cuts Act that was signed into law in December 2017, for taxable years beginning on or after January 1, 2018, the compensation deductible with respect to the Chief Executive Officer, the Chief Financial Officer, and the individuals serving as officers of our company or a subsidiary at the end of such year who are among the three highest compensated executive officers (other than the Chief Executive Officer and Chief Financial Officer) for proxy reporting purposes, as well as for individuals who were proxy officers for any taxable year beginning after December 31, 2016, Section 162(m) limits the amount of compensation otherwise deductible by our company and its subsidiaries for such year to $1,000,000. The "performance-based compensation" exception to this limitation generally is no longer applicable for awards granted after November 3, 2017 (but may be available for tax deductions for fiscal 2018 and subsequent years for grants made on or prior to that date).

The benefits that will be awarded or paid under the Plan are not currently determinable. Awards granted under the Plan are within the discretion of our Compensation Committee, and our Compensation Committee has not determined future awards or who might receive them. Information about awards granted in fiscal year 2017 under our prior plans to our named executive officers can be found in the table under the heading Grants of Plan-Based Awards. As of April 10, 2018, the closing price of a share of our common stock on the Nasdaq was $111.97.

The following table presents information as of December 31, 2017, regarding our securities authorized for issuance under equity compensation plans:

Certain outstanding stock options were issued under our Amended and Restated Equity Incentive Plan (the "Prior Plan"), which was approved by security holders in 1997. Information regarding this plan is contained in Note 9—Share-Based Compensation to the consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2017. No further awards may be granted pursuant to the Prior Plan following shareholder approval of the Plan in June 2015.

Approval of the Plan requires the affirmative vote of the holders of a majority of the outstanding shares present, in person or by proxy, at the meeting and entitled to vote on the proposal.

OUR BOARD OF DIRECTORS RECOMMENDS THAT SHAREHOLDERS VOTE "FOR" THE
APPROVAL OF THE 2018 AMENDMENT AND RESTATEMENT OF THE UNITED THERAPEUTICS
CORPORATION 2015 STOCK INCENTIVE PLAN.

PROPOSAL NO. 4
RATIFICATION OF THE APPOINTMENT OF
ERNST & YOUNG LLP AS UNITED THERAPEUTICS CORPORATION'S
INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM FOR 2018

The Audit Committee of our Board has appointed Ernst & Young LLP as our independent registered public accounting firm for the year 2018. Services provided to us and our subsidiaries by Ernst & Young LLP in 2017 are described under the section entitled Principal Accountant Fees and Services below.

We ask that our shareholders vote to ratify the appointment of Ernst & Young LLP as our independent registered public accounting firm. Although ratification is not required by our By-laws or otherwise, our Board has chosen to submit the ratification of Ernst & Young LLP's appointment to our shareholders as a matter of good corporate practice. In the event our shareholders do not ratify the appointment of Ernst & Young LLP, such appointment will be reconsidered by our Audit Committee and our Board. Even if the appointment of Ernst & Young LLP is ratified, our Audit Committee, in its discretion, may select a different independent registered public accounting firm at any time during the year if it determines that such a change would be in our best interests and those of our shareholders.

Representatives of Ernst & Young LLP are expected to be present at our Annual Meeting to respond to appropriate shareholder questions and to make such statements as they may desire.

OUR BOARD OF DIRECTORS RECOMMENDS THAT SHAREHOLDERS VOTE "FOR"
RATIFICATION OF THE APPOINTMENT OF ERNST & YOUNG LLP AS OUR
INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM FOR 2018.

As the members of the Audit Committee, we oversee United Therapeutics' financial reporting process on behalf of our Board of Directors. We are all independent directors under the listing standards of Nasdaq and the independence standards set forth in Rule 10A-3(b)(1) of the Exchange Act. Our Board has determined that Richard Giltner, our Audit Committee Chairman, is an audit committee financial expert as defined under the rules and regulations of the SEC and that each member of our Audit Committee meets the financial sophistication requirement of the Nasdaq listing standards. Our Audit Committee operates under a written charter, which we review periodically and which was adopted by our Board. Our charter is consistent with the provisions of the Sarbanes-Oxley Act of 2002, as well as the corporate governance rules issued by the SEC and Nasdaq, as they relate to audit committee requirements.

We have met and held discussions with management and our independent auditors. Management is responsible for the financial reporting process and preparation of United Therapeutics' quarterly and annual consolidated financial statements, including maintaining a system of internal controls and disclosure controls and procedures. Our Audit Committee is directly responsible for the appointment, compensation, retention, oversight and termination of our independent auditors. Ernst & Young LLP functioned as our independent auditors for 2017. Ernst & Young LLP is responsible for expressing an opinion on (i) the conformity of our financial statements with generally accepted accounting principles and (ii) our internal control over financial reporting. Our Audit Committee does not prepare financial statements or conduct audits.

In conjunction with the December 31, 2017, audited consolidated financial statements, we have:

Based on these reviews and discussions, our Audit Committee recommended to our Board of Directors that our audited consolidated financial statements for 2017 be included in our Annual Report on Form 10-K for the year ended December 31, 2017, as filed with the SEC.

Fees for professional services provided by Ernst & Young LLP in each of the last two years in each of the following categories were:

Audit fees include the aggregate fees billed for the audit of our consolidated annual financial statements, reviews of our interim consolidated financial statements included in quarterly reports, accounting and financial reporting consultations and services in connection with registration statements. Audit-related fees include the aggregate fees billed for assurance and related services that are reasonably related to the performance of the audit or review of our consolidated financial statements and are not reported as audit fees. Tax fees include the aggregate fees billed for professional services for tax compliance, tax advice and tax planning. "All other fees" included license fees for an accounting research online software tool.

The Audit Committee of our Board of Directors has considered and determined that the provision of non-audit services by Ernst & Young LLP is compatible with maintaining Ernst & Young LLP's independence. Since Ernst & Young LLP's appointment as our independent registered public accounting firm, our Audit Committee has pre-approved all of the services performed by Ernst & Young LLP.

Policy on Audit Committee Pre-Approval of Audit Services and Permissible Non-Audit Services of our Independent Auditors

Our Audit Committee's policy is to pre-approve all audit and permissible non-audit services performed by our independent auditors. These services may include audit services, audit-related services, tax services and other services. For audit services, our independent auditor provides an engagement letter to our Audit Committee prior to commencing its second-quarter review work, which letter outlines the scope of the proposed audit and audit-related fees. Our Audit Committee reviews the letter and negotiates with and formally engages the auditor.


Filed by the Registrant ý
Filed by a Party other than the Registrant o
Check the appropriate box:
o		Preliminary Proxy Statement
o		Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))
ý		Definitive Proxy Statement
o		Definitive Additional Materials
o		Soliciting Material under §240.14a-12

Name

Christopher Causey	19,210	38,250	1,620
Raymond Dwek	15,000	65,000	3,240
Richard Giltner	55,000	60,000	3,240
Katherine Klein	33,230	29,375	—
Ray Kurzweil	24,120	33,750	1,620
Judy Olian	35,000	—	3,240
Christopher Patusky	24,120	52,500	1,620
Louis Sullivan	39,120	75,000	1,620
Tommy Thompson	50,620	53,059	3,370

Executive Officer	2017 Base Salary⁽¹⁾								2017 Long-Term Incentive Award Target⁽³⁾		2017 Total Target Direct Compensation

Martine Rothblatt	$	1,180,000	5	%	110	%	0	%	$	14,000,000	$	16,478,000
James Edgemond	$	625,000	4	%	75	%	0	%	$	3,000,000	$	4,093,750
Michael Benkowitz	$	750,000	15	%	80	%	0	%	$	4,000,000	$	5,350,000
Paul Mahon	$	820,000	3	%	65	%	0	%	$	4,000,000	$	5,353,000

Title of Individual		Ownership Target

Chairman and Chief Executive Officer		Lesser of 6x base salary or 100,000 shares
President and Chief Operating Officer		Lesser of 3x base salary or 30,000 shares
Chief Financial Officer and Treasurer		Lesser of 3x base salary or 20,000 shares
Executive Vice President and General Counsel		Lesser of 3x base salary or 30,000 shares

Executive Officer		Minimum Base Salary under Agreement		Base Salary as of March 1, 2017

James Edgemond	March 2015	$	400,000	$	625,000
Michael Benkowitz	June 2016	$	650,000	$	750,000
Paul Mahon	June 2001	$	300,000	$	820,000


1040 Spring Street Silver Spring, MD 20910		55 T.W. Alexander Drive Research Triangle Park, NC 27709


		By Order of the Board of Directors,

		Paul A. Mahon Corporate Secretary

		PAGE

INFORMATION ABOUT THE MEETING, VOTING AND PROXIES		1
General		1
Record Date and Outstanding Shares		1
Internet Availability of Proxy Materials		1
Solicitation		1
Voting Rights and Quorum		2
Proxy		2
Voting Requirements		2
PROPOSAL NO. 1: Election of Directors		3
Nominees as Class I Directors for Election at our 2018 Annual Meeting of Shareholders		4
Class II Directors Continuing in Office with Terms Ending in 2019		7
Class III Directors Continuing in Office with Terms Ending in 2020		9
BOARD OF DIRECTORS, COMMITTEES, CORPORATE GOVERNANCE		12
The Role of our Board: Risk Oversight		12
Board of Directors Leadership		12
Director Nominations and Diversity		13
Director Independence		14
Committees of our Board of Directors		15
Corporate Governance Guidelines and Committee Charters		18
Stock Ownership Guidelines		18
Meetings of our Board of Directors and Board Attendance at Annual Meetings of Shareholders		18
Shareholder Communication with Directors		18
Proxy Access		19
Majority Voting		19
NON-EMPLOYEE DIRECTOR COMPENSATION		20
*Table: 2017 Non-Employee Director Compensation*		22
PROPOSAL NO. 2: Advisory Resolution to Approve Executive Compensation		23
LETTER FROM OUR COMPENSATION COMMITTEE CHAIRMAN		24
COMPENSATION DISCUSSION AND ANALYSIS		27
Overview of our 2017 Executive Compensation Program		27
Impact of 2017 Advisory Resolution on Executive Compensation		30
Key Governance Features of Our Executive Compensation Program		30
Review of 2017 Executive Compensation		32
*Table: Summary 2017 Target Total Direct Compensation*		32
Other Executive Compensation Policies and Practices		38
COMPENSATION COMMITTEE REPORT		42
EXECUTIVE COMPENSATION		43
*Table: Summary Compensation Table*		43
*Table: Supplementary 2017 Summary Compensation Table*		44
*Table: Grants of Plan-Based Awards in 2017*		46
Narratives to Summary Compensation Table and Grants of Plan-Based Awards in 2017 Table		47
Named Executive Officer Employment Agreements		47
Summary of Terms of Plan-Based Awards		48
*Table: Outstanding Equity Awards at 2017 Fiscal Year-End*		50
*Table: Option Exercises and Stock Vested in 2017*		51
*Table: Pension Benefits in 2017*		51
Supplemental Executive Retirement Plan		52

		PAGE

Potential Payments Upon Termination or Change in Control		53
*Table: Potential Payments Upon Termination or Change in Control*		54
Pay Ratio		57
PROPOSAL NO. 3: Approval of the Amendment and Restatement of the United Therapeutics Corporation 2015 Stock Incentive Plan		58
PROPOSAL NO. 4: Ratification of the Appointment of Ernst & Young LLP as United Therapeutics Corporation's Independent Registered Public Accounting Firm for 2018		69
REPORT OF OUR AUDIT COMMITTEE AND INFORMATION ON OUR INDEPENDENT AUDITORS		70
Report of our Audit Committee		70
Principal Accountant Fees and Services		72
Policy on Audit Committee Pre-Approval of Audit Services and Permissible Non-Audit Services of our Independent Auditors		72
OTHER MATTERS		73
Certain Relationships and Related Party Transactions		73
Beneficial Ownership of Common Stock		74
Section 16(a) Beneficial Ownership Reporting Compliance		76
Shareholder Proposals and Director Nominations		76
Other Business		77
Shareholders Sharing the Same Address		77
Annual Report		78
Attending the Annual Meeting		78
Annex A—Amended and Restated United Therapeutics Corporation 2015 Stock Incentive Plan		A-1
Proxy Card

			Value of Equity-Based Awards⁽³⁾

	Annual Cash		Value of Equity-Based Awards⁽³⁾
	Annual Cash		Initial		Annual
Board Membership	$	60,000	$	400,000	$	400,000
Lead Independent Director⁽¹⁾	$	35,000		—		—
Committee Chairmanship⁽²⁾:
Audit Committee	$	25,000		—		—
Compensation Committee	$	25,000		—		—
Nominating and Governance Committee	$	25,000		—		—
Committee Membership⁽²⁾:
Audit Committee	$	15,000		—		—
Compensation Committee	$	15,000		—		—
Nominating and Governance Committee	$	15,000		—		—

Name	Fees Earned or Paid in Cash⁽¹⁾		Restricted Stock Units⁽²⁾		Stock Options⁽²⁾		All Other Compensation		Total

Christopher Causey	$	100,000	$	214,326	$	206,627	$	—	$	520,953
Raymond Dwek	$	60,000	$	428,652	$	—	$	—	$	488,652
Richard Giltner	$	100,000	$	428,652	$	—	$	—	$	528,652
Katherine Klein	$	60,000	$	—	$	412,763	$	—	$	472,763
Ray Kurzweil	$	60,000	$	214,326	$	206,627	$	—	$	480,953
Judy Olian	$	75,000	$	428,652	$	—	$	—	$	503,652
Christopher Patusky	$	150,000	$	214,326	$	206,627	$	—	$	570,953
Louis Sullivan	$	90,000	$	214,326	$	206,627	$	—	$	510,953
Tommy Thompson	$	75,000	$	214,326	$	206,627	$	—	$	495,953


		RESOLVED, that the shareholders of United Therapeutics Corporation (our "Company") approve, on an advisory basis, the compensation of our Company's Named Executive Officers disclosed in the **Compensation Discussion and Analysis, the Summary Compensation Table and the related compensation tables, notes and narrative in the Proxy Statement for our Company's 2018 Annual Meeting of Shareholders.**


		Sincerely,

		Christopher Causey Compensation Committee
		Chairman

	Objective

Compensation Element	Pay for Performance	Shareholder Alignment	Balance Short- and Long-Term Perspectives	Market Competitiveness
Base Salary				ü
Cash Incentive Awards	ü	ü	ü	ü
Long-Term Incentives (Stock Options/STAPs)	ü	ü	ü	ü
Benefits/Perquisites				ü
Supplemental Executive Retirement Plan (SERP)			ü
Severance/Change-of-Control Benefits			ü	ü
Stock Ownership Guidelines		ü	ü

	Range (Target to Stretch)

Revenue Performance	$	1.75 billion		$	1.925 billion
Cash Profit Performance	$	950 million		$	1.045 billion
Multiplier for each Metric*		0	%		25	%

Executive Officer	2017 Base Salary (A)								Total Cash Incentive Bonus Earned (A × B × C × D)

Martine Rothblatt	$	1,180,000	110	%	98.5	%	125	%	$	1,598,163
James Edgemond	$	625,000	75	%	98.5	%	125	%	$	577,148
Michael Benkowitz	$	750,000	80	%	98.5	%	125	%	$	738,750
Paul Mahon	$	820,000	65	%	98.5	%	125	%	$	656,256

	2017 Milestone Performance Option Award (Granted on March 15, 2017) (50% of Overall Opportunity)

Executive Officer	Milestone Performance Option Award Opportunity (Target) (#) (A)		Earned Award as % of 2017 Target (B)			Long-Term Incentive Award Earned (#) (A × B)
Martine Rothblatt		122,061		123.1	%		150,288
James Edgemond		26,156		123.1	%		32,205
Michael Benkowitz		34,875		123.1	%		42,940
Paul Mahon		34,875		123.1	%		42,940


		Submitted by the Compensation Committee: Christopher Causey (Chair) Judy Olian Christopher Patusky Louis Sullivan

	Option Awards				STAP Awards

Name	Number of Shares Acquired on Exercise (#)		Value Realized on Exercise ($)⁽¹⁾		Number of STAP Awards Exercised (#)		Value Realized on Exercise ($)⁽¹⁾
Martine Rothblatt		110,273	$	10,942,594		—	$	—
James Edgemond		—	$	—		—	$	—
Michael Benkowitz		—	$	—		—	$	—
Paul Mahon		—	$	—		144,000	$	11,220,200

Name	Plan Name			Present Value of Accumulated Benefit ($)⁽³⁾

Martine Rothblatt	SERP	15.0	21.5	$	16,436,226
James Edgemond	SERP	4.9	5.0	$	1,894,422
Michael Benkowitz	SERP	6.7	6.7	$	2,345,764
Paul Mahon	SERP	15.0	16.5	$	10,213,749


Total shares underlying all outstanding stock options		6,454,207
Weighted average exercise price of outstanding stock options	$	120.98
Weighted average remaining contractual life of outstanding stock options		7.5 years
Total shares of common stock outstanding		43,544,022
Total shares underlying all outstanding and unvested performance shares		0
Total shares underlying all outstanding and unvested restricted stock (excluding performance shares)		176,676
Shares available for future awards that could be issued under Prior Plan⁽¹⁾		0
Shares available for future awards that could be issued under the 2015 Stock Incentive Plan⁽²⁾		1,364,293



Fiscal 2017	1,958,843	21,290	1,980,133	44,004,303	4.5	%
Fiscal 2016	1,630,552	20,960	1,651,512	43,761,724	3.8	%
Fiscal 2015	172,250	0	172,250	45,999,724	0.4	%
Three-Year Average	1,253,882	14,083	1,267,965	44,588,584	2.8	%

Plan category		Weighted average exercise price of outstanding options (b)

Equity compensation plan approved by security holders	5,901,363	$	119.61	5,362,968
Equity compensation plans not approved by security holders	—		—	N/A

Total	5,901,363	$	119.61	5,362,968


		Submitted by the Audit Committee: Richard Giltner (Chair) Christopher Patusky Tommy Thompson

	2017		2016

Audit fees	$	2,207,518	$	1,705,114
Audit-related fees		194,000		14,300
Tax fees:
Fees for tax compliance services		398,373		415,234
Fees for tax consulting services (including tax advice and tax planning)		228,256		225,404

Total tax fees		626,629		640,638
All other fees		1,995		1,995

	$	3,030,142	$	2,362,047