Atara Biotherapeutics, Inc. has 11 Schedule 13D or 13G filings on record since 2025-08-19. 5 holders' latest filing reports 5% or more of common stock, par value $0.0001 per share. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| EcoR1 Capital, LLC | 17.4% | 1,552,000 | SCHEDULE 13G/A, 2026-05-07 | 2026-05-07 |
| Panacea Innovation Limited | 16.1% | 1,318,894 | SCHEDULE 13D/A, 2026-05-11 | 2026-05-07 |
| Redmile Group, LLC | 9.9% | 950,994 | SCHEDULE 13D/A, 2026-07-24 | 2026-07-22 |
| Adage Capital Management, L.P. | 8.56% | 700,000 | SCHEDULE 13G, 2026-05-13 | 2026-03-31 |
| Point72 Asset Management, L.P. | 7.6% | 687,718 | SCHEDULE 13G/A, 2026-08-14 | 2026-06-30 |
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-08-19 | Panacea Innovation Limited | 20% | SCHEDULE 13D/A |
| 2025-11-14 | EcoR1 Capital, LLC | 9.9% | SCHEDULE 13G/A |
| 2025-11-14 | Redmile Group, LLC | 9.9% | SCHEDULE 13D/A |
| 2026-01-14 | Panacea Innovation Limited | 19.99% | SCHEDULE 13D/A |
| 2026-05-07 | EcoR1 Capital, LLC | 17.4% | SCHEDULE 13G/A |
| 2026-05-08 | Point72 Asset Management, L.P. | 6.2% | SCHEDULE 13G |
| 2026-05-11 | Panacea Innovation Limited | 16.1% | SCHEDULE 13D/A |
| 2026-05-13 | Adage Capital Management, L.P. | 8.56% | SCHEDULE 13G |
| 2026-05-14 | Redmile Group, LLC | 9.9% | SCHEDULE 13D/A |
| 2026-07-24 | Redmile Group, LLC | 9.9% | SCHEDULE 13D/A |
| 2026-08-14 | Point72 Asset Management, L.P. | 7.6% | SCHEDULE 13G/A |
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.