X0306 4 2018-07-23 0 0001552451 MyoKardia Inc MYOK 0001654909 Bauer Jake C/O MYOKARDIA, INC. 333 ALLERTON AVENUE SOUTH SAN FRANCISCO CA 94080 0 1 0 0 Chief Business Officer Common Stock 2018-07-23 4 M 0 7500 13.90 A 68106 D Common Stock 2018-07-23 4 S 0 4399 56.59 D 63707 D Common Stock 2018-07-23 4 S 0 3101 57.28 D 60606 D Stock Option (Right to Buy) 13.90 2018-07-23 4 M 0 7500 0.00 D 2027-07-19 Common Stock 7500 7500 D This transaction was effective 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 $56.00 to $56.95 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 $57.00 to $57.60 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. The shares subject to this option vest and become exercisable in in two annual installments after July 20, 2017, so long as the Reporting Person continues to be an employee of the Issuer through each vesting date. Exhibit 24.1 - Power of Attorney /s/ Cynthia J. Ladd, Attorney-in-Fact 2018-07-25