---
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"
generated_at: "2026-06-01T03:25:47.144188+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.5
calibrated_materiality_score: 0.5
confidence: "high"
source: SEC EDGAR
---

# Atara Biotherapeutics effects 1:25 reverse stock split effective June 20, 2024

## Summary
- 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.

## SEC filing metadata
- 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
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.5
- calibrated_materiality_score: 0.5
- confidence: high
- sec_items: 3.03, 5.03, 9.01
- 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

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-24-164554
- JSON: https://secwatch.observer/filing/0001193125-24-164554.json
- Plain text: https://secwatch.observer/filing/0001193125-24-164554.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.