0001604464 2026-08-12 2026-08-12 0001604464 false 8-K 2026-08-12 Atara Biotherapeutics, Inc. DE 001-36548 46-0920988 1280 Rancho Conejo Blvd Thousand Oaks CA 91320 (805) 623-4211 false false false false Common Stock, par value $0.0001 per share ATRA NASDAQ false