X0508 4 2023-08-16 0001604464 Atara Biotherapeutics, Inc. ATRA 0001809916 Murugan Amar C/O ATARA BIOTHERAPEUTICS, INC. 2380 CONEJO SPECTRUM ST, SUITE 200 THOUSAND OAKS CA 91320 true EVP, Chief Legal Officer false Common Stock 2023-08-16 4 S 0 5050 1.652 D 269013 D Common Stock 2023-08-16 4 S 0 3622 1.653 D 265391 D Shares sold automatically to satisfy tax withholding obligations in connection with the vesting of previously granted restricted stock units, pursuant to a sale-to-cover provision in the award agreement. The sale price of the reporting person's shares represents the weighted average price of all shares sold by a broker on August 16, 2023 and August 17, 2023 on behalf of a group of employees of the Issuer to satisfy the payment of withholding tax liability of such employee. Includes 3,118 shares purchased under the Issuer's Employee Stock Purchase Plan on May 31, 2023. /s/ Jeff Kiekhofer, Attorney-in-Fact for Amar Murugan 2023-08-18