X0306 4 2016-11-01 0 0001552451 MyoKardia Inc MYOK 0001654907 Chan Steven C/O MYOKARDIA, INC. 333 ALLERTON AVENUE SOUTH SAN FRANCISCO CA 94080 0 1 0 0 See Remarks Stock Option (Right to Buy) 1.51 2016-11-01 4 A 0 2041 0.00 A 2016-11-01 2025-06-03 Common Stock 2041 2041 D On June 4, 2015, the Reporting Person was granted an option to purchase 8,163 shares of Common Stock under the issuer's 2012 Equity Incentive Plan, the vesting of which was subject to various conditions (other than the passage of time and continued employment) that were not tied to the market price of the issuer's securities. On November 1, 2016, one of the conditions was deemed to be achieved, resulting in the vesting and exercisability of 2,041 of the shares underlying such option. Vice President, Corporate Controller /s/ Steven Chan 2016-11-02