X0306 4 2020-01-01 0 0001552451 MyoKardia Inc MYOK 0001413822 GIANAKAKOS ANASTASIOS C/O MYOKARDIA INC. 333 ALLERTON AVENUE SOUTH SAN FRANCISCO CA 94080 1 1 0 0 President and CEO Common Stock 2020-01-01 4 M 0 27950 A 114464 D Common Stock 2020-01-03 4 S 0 300 70.35 D 114164 D Common Stock 2020-01-03 4 S 0 2616 71.5927 D 111548 D Common Stock 2020-01-03 4 S 0 2084 72.2728 D 109464 D Common Stock 225947 I By Reporting Person's Trust 2 Common Stock 323526 I By Reporting Person's Trust 3 Common Stock 12200 I By Trust 1 Common Stock 12200 I By Trust 2 Common Stock 12200 I By Trust 3 Restricted Stock Units 2020-01-01 4 M 0 7650 0.00 D Common Stock 7650 15300 D Restricted Stock Units 2020-01-01 4 M 0 20300 0.00 D Common Stock 20300 60900 D Restricted stock units convert into common stock on a one-for-one basis. Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Issuer's Common Stock. The shares of Common Stock underlying the RSUs vest in equal annual installments over 4 years from January 1, 2018, so that all of the underlying shares shall be vested on January 1, 2022, subject to the Reporting Person's continued employment with the Issuer through each vesting date. The RSUs are subject to accelerated vesting upon termination without cause after a change of control of the Issuer. Each RSU represents a contingent right to receive one share of Issuer's Common Stock. The shares of Common Stock underlying the RSUs vest in equal annual installments over 4 years from January 1, 2019, so that all of the underlying shares shall be vested on January 1, 2023, subject to the Reporting Person's continued employment with the Issuer through each vesting date. The RSUs are subject to accelerated vesting upon termination without cause after a change of control of the Issuer. This transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person. Represents the weighted average sale price of the shares sold ranging from $69.93 to $70.56 per share. The Reporting Person will provide, upon request by the Commission staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price. Represents the weighted average sale price of the shares sold ranging from $70.99 to $71.98 per share. The Reporting Person will provide, upon request by the Commission staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price. Represents the weighted average sale price of the shares sold ranging from $72.03 to $72.73 per share. The Reporting Person will provide, upon request by the Commission staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price. /s/ Cynthia J. Ladd, as Attorney-in-Fact 2020-01-03