Certain Common Stock of Achillion Pharmaceuticals, Inc. are subject to a Lock-Up Agreement Ending on 14-JAN-2018. These Common Stock will be under lockup for 60 days starting from 15-NOV-2017 to 14-JAN-2018. Details: The executive officers and directors have agreed that they will not sell, directly or indirectly, any shares of common stock without the permission of Goldman Sachs & Co. LLC and Leerink Partners LLC for a period of 60 days following the date of this prospectus supplement.