{"schema_version":"secwatch.filing_event.v1","accession":"0000950170-25-030832","form_type":"8-K","ticker":"ATRA","cik":"0001604464","company_name":"Atara Biotherapeutics, Inc.","filed_at":"2025-03-03T23:59:59+00:00","discovered_at":"2026-05-14T18:03:04.165563+00:00","generated_at":"2026-05-25T17:46:42.562471+00:00","sec_items":["2.05","9.01"],"event_type":"other_material","sentiment":"negative","materiality_score":0.75,"calibrated_materiality_score":0.75,"confidence":"high","headline":"Atara Biotherapeutics cuts 50% of workforce, discontinues two CAR T programs","bullets":["Reducing workforce by ~50%; expected to substantially complete by June 2025.","Discontinuing all development for ATA3219 and ATA3431, including CAR T clinical studies.","Estimated severance and related benefits of $3.0 million, primarily one-time cash charges.","Additional details to be provided in the Q1 2025 10-Q filing."],"urls":{"canonical":"https://secwatch.observer/filing/0000950170-25-030832","json":"https://secwatch.observer/filing/0000950170-25-030832.json","markdown":"https://secwatch.observer/filing/0000950170-25-030832.md","text":"https://secwatch.observer/filing/0000950170-25-030832.txt","edgar_index":"https://www.sec.gov/Archives/edgar/data/1604464/000095017025030832/0000950170-25-030832-index.htm","edgar_primary_document":"https://www.sec.gov/Archives/edgar/data/1604464/000095017025030832/atra-20250303.htm"},"model":{"generated_by":"deepseek-v4-flash:cloud@v2","generated_at":"2026-05-25T17:46:42.562471+00:00"},"review":{"review_status":"machine_generated","human_reviewed":false,"corrected":false,"correction_note":null,"correction_timestamp":null,"superseded_by":null,"related_filings":[]},"source_grounded_claims":[],"license":"Source filings: public domain (SEC EDGAR). Summaries (headline + bullets): CC-BY-4.0; attribute https://secwatch.observer"}