144 0001978096 XXXXXXXX LIVE 0001604464 Atara Biotherapeutics, Inc. 001-36548 c/o Atara Biotherapeutics, Inc. 1280 Rancho Conejo Boulevard Thousand Oaks CA 91320 805-623-4211 Henrich Jill Officer Common Stock Morgan Stanley Smith Barney LLC

Executive Services 200 W Civic Center Drive, 4th Floor Sandy UT 84070

1245 8602.95 5858909 03/03/2025 NASDAQ Common Stock 03/01/2025 Settlement of vested RSUs issued under an S-8 Registration Plan Issuer N 2518 03/01/2025 Equity compensation for services rendered Y 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. 03/03/2025 /s/ John Chao, Attorney-in-Fact for Jill Henrich