Atara Biotherapeutics Inc
Ownership
Ownership Structure
Who owns Atara Biotherapeutics Inc (ATRA)? This page shows the largest institutions and funds, the ownership structure and the latest insider transactions. 46.1% of the shares are freely tradable; institutional investors hold 52.5%.
Largest Shareholders
Institutions
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| EcoR1 Capital, LLC | 15.46 | 1,552,000 | +1,458.3 | 06/30/2026 |
| Adage Capital Partners Gp LLC | 8.47 | 850,000 | +21.4 | 06/30/2026 |
| Redmile Group, LLC | 4.40 | 441,701 | +0.0 | 06/30/2026 |
| Mackenzie Investments | 3.12 | 313,620 | +434.6 | 03/31/2026 |
| Vanguard Capital Management, LLC | 2.17 | 217,862 | +0.0 | 03/31/2026 |
| Point72 Asset Management, L.P. | 1.94 | 194,264 | +961.8 | 03/31/2026 |
| Acadian Asset Management LLC | 1.30 | 130,910 | +0.0 | 03/31/2026 |
Funds
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| Vanguard MStar Total Stk Mkt Idx Invest | 1.58 | 158,646 | +0.0 | 07/31/2026 |
| Mackenzie Quantitative US Small Cap | 0.89 | 89,727 | -46.4 | 06/30/2026 |
| Vanguard Institutional Extnd Mkt Idx Tr | 0.82 | 82,758 | +0.0 | 07/31/2026 |
Largest reported positions according to regulatory filings; stake as a percentage of shares outstanding, change versus the previous filing. Source: fundamentals data.
Insider holdings
| Person | Role | Shares | Value | As of | Type |
|---|---|---|---|---|---|
| Redmile Group, LLC | Director | 636,852 | 6,177,464 $ | Jul 22, 2026 | indirect |
| Cherry Brian N | Director | 166,486 | 1,614,914 $ | Sep 4, 2026 | direct |
| Nguyen AnhCo | President and CEO | 132,775 | 1,287,918 $ | Aug 17, 2026 | direct |
Holdings as of each person's most recent SEC Form 4 filing — excluding options and RSUs, which are not shares yet. Holdings may have changed between two filings.
Insiders
Insider Transactions
| Date | Person | Role | Type | Shares | Price | Value |
|---|---|---|---|---|---|---|
| Sep 4, 2026 | Cherry Brian N | Director | Buy | 104,166 | 9.60 | 999,994 |
| Aug 17, 2026 | Nguyen AnhCo | President and CEO | Sell | 5,062 | 8.08 | 40,883 |
| Jul 22, 2026 | Redmile Group, LLC | Director | Other | 60 | – | – |
| Jul 22, 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: September 17, 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.