X0306 4 2020-03-27 0 0001604464 Atara Biotherapeutics, Inc. ATRA 0001742696 Koppikar Utpal C/O ATARA BIOTHERAPEUTICS, INC. 611 GATEWAY BLVD., SUITE 900 SOUTH SAN FRANCISCO CA 94080 0 1 0 0 Chief Financial Officer Common Stock 2020-03-27 4 S 0 1827 9.17 D 137330 D Represents the number of shares required to be sold by the reporting person to cover tax withholding obligations in connection with the vesting of Restricted Stock Units. This sale is mandated by the Issuer's election under its equity incentive plans to require the satisfaction of tax withholding obligations to be funded by a "sell to cover" transaction and does not represent a discretionary trade by the reporting person. The sale is intended to comply with the requirements of Rule 10b5-1(c)(1)(i)(B) under the Exchange Act and be interpreted to meet the requirements of Rule 10b5-1(c). /s/ David Tucker, Attorney-in-Fact for Utpal Koppikar 2020-03-30