X0508 4 2024-03-04 0001604464 Atara Biotherapeutics, Inc. ATRA 0001977970 Nguyen AnhCo C/O ATARA BIOTHERAPEUTICS, INC. 2380 CONEJO SPECTRUM ST, SUITE 200 THOUSAND OAKS CA 91320 true EVP, Chief Sci. & Tech Officer false Common Stock 2024-03-04 4 S 0 10746 0.72 D 941397 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 March 4, 2024 and March 5, 2024 on behalf of a group of employees of the Issuer to satisfy the payment of withholding tax liability of such employees. /s/ John Chao, Attorney-in-Fact for AnhCo Nguyen 2024-03-06