X0306 4 2023-03-01 0001604464 Atara Biotherapeutics, Inc. ATRA 0001809916 Murugan Amar C/O ATARA BIOTHERAPEUTICS, INC. 2380 CONEJO SPECTRUM ST, SUITE 200 THOUSAND OAKS CA 91320 true SVP, GC & Secretary Common Stock 2023-03-01 4 A 0 155375 0 A 283555 D Employee Stock Option (Right to Buy) 3.91 2023-03-01 4 A 0 349593 0 A 2033-02-28 Common Stock 349593 349593 D These restricted stock units vest in 12 equal quarterly installments on each Company Quarterly Vesting Date (as defined below), with the initial installment vesting on May 15, 2023, subject to the reporting person's continuous service. "Company Quarterly Vesting Date" means March 1, May 15, August 15 and November 15 of each year. Includes 594 shares purchased under the Issuer's Employee Stock Purchase Plan on November 30, 2022. 1/36th of the shares subject to the stock option vest and become exercisable each month, with the initial installment vesting on April 1, 2023, subject to the reporting person's continuous service. /s/ Jeff Kiekhofer, Attorney-in-Fact for Amar Murugan 2023-03-03