ACHN 2018 Proxy Statement

Board of Directors Meetings and Attendance Our Board of Directors held five meetings, either in person or by teleconference, during the year ended December 31, 2017, or fiscal 2017. During fiscal 2017, each of our current directors attended at least 75% of the aggregate number of Board of Directors meetings and meetings held by all committees on which he or she then served. Our Corporate Governance Guidelines provide that our directors are expected to attend the Annual Meeting of Stockholders. In 2017, all of our directors attended the Annual Meeting of Stockholders. Board of Directors Committees Our Board of Directors has established five standing committees—Audit, Compensation, Nominating and Corporate Governance, Compliance and Strategy. These committees each operate under a written charter that has been approved by the Board of Directors. Current copies of the charters for these committees are posted on the Corporate Governance section of our website, www.achillion.com . Our Board of Directors has determined that all of the members of our Audit, Compensation, Nominating and Corporate Governance, Compliance and Strategy committees are independent as defined under the rules of the Nasdaq Stock Market, including, in the case of all members of the Audit Committee, the independence requirements contemplated by Rule 10A-3 under the Exchange Act and in the case of all members of the Compensation Committee, the independence requirements contemplated by Rule 10C-1 under the Exchange Act. The chart below lists the standing committees of our Board of Directors and indicates who currently serves on those committees and how many meetings each committee held during fiscal 2017. Board of Directors Member Audit Compensation Nominating and Corporate Governance Compliance Strategy Jason Fisherman, M.D. Gary Frashier Kurt Graves ‘ Michael Kishbauch David Scheer ‘ ‘ Robert Van Nostrand ‘ Frank Verwiel, M.D. ‘ Nicole Vitullo Meetings in fiscal 2017 4 7 4 1 1 ‘ Committee Chair Committee Member Our Board of Directors has determined that Mr. Van Nostrand is an “audit committee financial expert” as defined by applicable SEC rules. Audit Committee Our Audit Committee’s responsibilities include: • appointing, approving the compensation of, and assessing the independence of our independent registered public accounting firm; • overseeing the work of our independent registered public accounting firm, including through the receipt and consideration of reports from such firm; 30