ACHN 2017 Annual Report

The following graph compares the cumulative total stockholder return on our common stock from December 31, 2012 to December 31, 2017 with the cumulative total return of (i) the NASDAQ Market Index and (ii) the NASDAQ Biotechnology Index. This graph assumes the investment of $100.00 after the market closed on December 31, 2012 in our common stock, and in the NASDAQ Market Index and the NASDAQ Biotechnology Index, and it assumes any dividends are reinvested. The stock price performance included in this graph is not necessarily indicative of future stock price performance. COMPARISON OF CUMULATIVE TOTAL RETURN AMONG ACHILLION PHARMACEUTICALS, INC., NASDAQ MARKET INDEX AND NASDAQ BIOTECH INDEX 0 50 100 150 200 250 300 12/31/2017 12/31/2016 12/31/2012 12/31/2013 12/31/2014 12/31/2015 DOLLARS ACHILLION PHARMACEUTICALS, INC. NASDAQ BIOTECH INDEX NASDAQ MARKET INDEX ASSUMES $100 INVESTED ON JAN. 01, 2013 ASSUMES DIVIDEND REINVESTED FISCAL YEAR ENDING DEC. 31, 2017 74