ACHN 2018 Proxy Statement

Executive Compensation The following table shows the total compensation paid or accrued for the fiscal years indicated below for our Chief Executive Officer, our Chief Financial Officer, and our two other most highly compensated executive officers who served as executive officers as of December 31, 2017, as well as two additional individuals who would have been included among our most highly compensated executive officers if they had been serving as such on December 31, 2017. We refer to these officers as our named executive officers. SUMMARY COMPENSATION TABLE Name and Principal Position Year Salary ($) Option Awards (1) ($) Non-Equity Incentive Plan Compensation ($) All Other Compensation ($) Total ($) Milind Deshpande, Ph.D. . . . . . . . . . 2017 607,700 1,335,258(2) 260,703(3) 8,557(4) 2,212,218 Director and Chief Executive Officer 2016 590,000 2,153,727(5) 218,144(6) 8,310(7) 2,970,181 2015 525,100 — (8) 416,667(9) 8,298(10) 950,065 Mary Kay Fenton, . . . . . . . . . . . . . . . . 2017 382,130 481,043(2) 120,218(3) 8,557(4) 991,948 Executive Vice President, Chief Financial Officer and Treasurer 2016 371,000 635,350(5) 101,932(6) 8,310(7) 1,116,592 2015 360,140 — (8) 159,452(9) 8,298(10) 527,890 Martha Manning . . . . . . . . . . . . . . . . . 2017 339,900 393,580(2) 89,313(3) 45,885(11) 868,678 Executive Vice President, General Counsel and Corporate Secretary Joseph Truitt, . . . . . . . . . . . . . . . . . . . . 2017 389,971(12) 539,351(2) 122,582(3) 8,557(4) 1,060,461 President and Chief Operating Officer 2016 371,000 764,573(5) 112,125(6) 8,310(7) 1,256,008 2015 347,429 — (8) 167,808(9) 28,219(13) 543,456 David Apelian, M.D., Ph.D. . . . . . . . 2017 500,065(14) 539,351(2) — (15) 32,782(16) 1,072,198 Former Executive Vice President and Chief Medical Officer 2016 485,500 635,350(5) 140,060(6) 32,652(17) 1,293,562 2015 471,328 — (8) 199,195(9) 32,340(18) 702,863 Joel Barrish, Ph.D. . . . . . . . . . . . . . . . 2017 244,031(19) 539,351(2) (100,000)(20) 27,136(21) 710,518 Former Executive Vice President and Chief Scientific Officer 2016 423,077(22) 1,938,425(23) 339,023(24) 45,638(25) 2,746,163 (1) The amounts in this column reflect the aggregate grant date fair value of the option awards granted in accordance with ASC 718, Stock Compensation. There can be no assurance that the amounts recognized in accordance with ASC 718 will ever be realized. The assumptions we used to calculate these amounts are included in Note 11 to our audited financial statements for fiscal 2017, included in our annual report on Form 10-K for the fiscal year ended December 31, 2017 filed with the SEC on February 22, 2018. (2) Represents stock option awards made in January 2017 with respect to 2016 performance. (3) Represents the discretionary cash performance-based bonus awards approved by the Compensation Committee in February 2018 in connection with our annual performance review process for 2017 performance. (4) Represents $457 of life insurance premiums paid by Achillion and $8,100 in matching contributions pursuant to Achillion’s 401(k) defined contribution plan. (5) Represents stock option awards made in January 2016 with respect to 2015 performance. (6) Represents the discretionary cash performance-based bonus awards approved by the Compensation Committee in January 2017 in connection with our annual performance review process for 2016 performance. (7) Represents $360 of life insurance premiums paid by Achillion and $7,950 in matching contributions pursuant to Achillion’s 401(k) defined contribution plan. (8) In 2016, the timing of our annual compensation review changed from the end of the fiscal year to the beginning of the next fiscal year. Stock option awards made with respect to 2015 performance were awarded in 2016. (9) Represents the discretionary cash performance-based bonus awards approved by the Compensation Committee in December 2015 in connection with our annual performance review process for 2015 performance. 45