{"schema_version":"secwatch.filing_event.v1","accession":"0001193125-24-164554","form_type":"8-K","ticker":"ATRA","cik":"0001604464","company_name":"Atara Biotherapeutics, Inc.","filed_at":"2024-06-20T23:59:59+00:00","discovered_at":"2026-05-14T18:03:19.185377+00:00","generated_at":"2026-06-01T03:25:47.144188+00:00","sec_items":["3.03","5.03","9.01"],"event_type":"other_material","sentiment":"neutral","materiality_score":0.5,"calibrated_materiality_score":0.5,"confidence":"high","headline":"Atara Biotherapeutics effects 1:25 reverse stock split effective June 20, 2024","bullets":["Reverse stock split ratio of 1:25 approved by board on June 10, effective June 20.","Common stock begins trading on split-adjusted basis under new CUSIP 046513206.","No fractional shares; cash payment based on closing price prior to effective date.","Stockholders approved proposal at annual meeting on June 10, 2024.","Amendment filed with Delaware Secretary of State."],"urls":{"canonical":"https://secwatch.observer/filing/0001193125-24-164554","json":"https://secwatch.observer/filing/0001193125-24-164554.json","markdown":"https://secwatch.observer/filing/0001193125-24-164554.md","text":"https://secwatch.observer/filing/0001193125-24-164554.txt","edgar_index":"https://www.sec.gov/Archives/edgar/data/1604464/000119312524164554/0001193125-24-164554-index.htm","edgar_primary_document":"https://www.sec.gov/Archives/edgar/data/1604464/000119312524164554/d843613d8k.htm"},"model":{"generated_by":"deepseek-v4-flash:cloud@v2","generated_at":"2026-06-01T03:25:47.144188+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"}