X0609 4 2026-05-18 0001604464 Atara Biotherapeutics, Inc. ATRA 0002064348 Grant-Huerta Yanina false C/O ATARA BIOTHERAPEUTICS, INC. 1280 RANCHO CONEJO BOULEVARD THOUSAND OAKS CA 91320 true Chief Accounting Officer false Common Stock 2026-05-18 4 S 0 2414 9.1286 D 49636 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. Represents the weighted average price. The shares were sold in multiple transactions at prices ranging from $9.12 to $9.40, inclusive. The Reporting Person undertakes to provide to the Issuer, any securityholder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above. /s/ John Chao, Attorney-in-Fact for Yanina Grant-Huerta 2026-05-20