Atara Biotherapeutics Inc (ATRA)
Who owns Atara Biotherapeutics Inc (ATRA)? This page shows the largest institutions and funds, the ownership structure and the latest insider transactions. 51.7% of the shares are freely tradable; institutional investors hold 52.5%.
Ownership Structure
Largest Shareholders
Institutions
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| Adage Capital Partners Gp LLC | 7.77 | 700,000 | +0.0 | 03/31/2026 |
| Redmile Group, LLC | 4.90 | 441,701 | +0.0 | 03/31/2026 |
| Mackenzie Investments | 3.48 | 313,620 | +434.6 | 03/31/2026 |
| Vanguard Group Inc | 2.51 | 225,940 | +11.1 | 12/31/2025 |
| Vanguard Capital Management, LLC | 2.42 | 217,862 | +0.0 | 03/31/2026 |
| Point72 Asset Management, L.P. | 2.16 | 194,264 | +961.8 | 03/31/2026 |
| Acadian Asset Management LLC | 1.45 | 130,910 | +0.0 | 03/31/2026 |
| EcoR1 Capital, LLC | 1.11 | 99,593 | -82.6 | 03/31/2026 |
Funds
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| Mackenzie Quantitative US Small Cap | 1.86 | 167,395 | +1,198.6 | 03/31/2026 |
| Vanguard Total Stock Mkt Idx Inv | 1.76 | 158,646 | +0.0 | 04/30/2026 |
Largest reported positions according to regulatory filings; stake as a percentage of shares outstanding, change versus the previous filing. Source: fundamentals data.
Insider Transactions
| Date | Person | Role | Type | Shares | Price | Value |
|---|---|---|---|---|---|---|
| 22. Jul 2026 | Redmile Group, LLC | Director | Other | 60 | – | – |
| 22. Jul 2026 | Redmile Group, LLC | Director | Other | 195,211 | – | – |
Reportable transactions by officers and major shareholders from SEC Form 4 filings. "Other" includes things like stock grants and option exercises without a buy/sell character.
View all insider transactions →Data as of: July 31, 2026 · Source: fundamental data & SEC filings (annual and quarterly reports, 10-K/10-Q)
Note: pure fact-based analysis, not investment advice and not a solicitation to buy or sell. All figures without guarantee.