X0306 4/A 2016-12-21 2016-12-22 0 0001280600 ACCELERON PHARMA INC XLRN 0001117003 MCGUIRE TERRANCE ONE MARINA PARK DRIVE, SUITE 1100 BOSTON MA 02210 1 0 0 0 Common Stock 0 D On December 22, 2016, due to a clerical error, the Reporting Person inadvertently filed a Form 4 reporting the receipt of 2,190 shares pursuant to a pro rata distribution and not a purchase or sale, without additional consideration by Polaris Venture Partners IV, L.P. and Polaris Venture Partners Entrepreneurs' Fund IV, L.P. to their respective limited partners and general partner, Polaris Venture Management Co. IV, L.L.C. As of December 21, 2016 the Reporting Person held 0 shares of the Issuer's common stock. This amendment corrects this clerical error. /s/ Terrance McGuire 2017-03-08