As of November 6, 2026, 5 holders' latest Schedule 13D or 13G filings report owning 5% or more of Atara Biotherapeutics, Inc. The largest reported stake is EcoR1 Capital, LLC's, at 17.4%. 11 filings are on record since August 19, 2025 (Schedule 13G/A, May 7, 2026).
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Key facts
- · Reporting person: Point72 Asset Management, L.P. · Sole voting: 0 · Shared voting: 687,718 · Sole dispositive: 0 · Shared dispositive: 687,718 · SCHEDULE 13G/A, 2026-08-14
- · Reporting person: Redmile Group, LLC · Sole voting: 0 · Shared voting: 950,994 · Sole dispositive: 0 · Shared dispositive: 950,994 · SCHEDULE 13D/A, 2026-07-24
- · Holder: Redmile Group, LLC · Percent: 9.9% · SCHEDULE 13D/A
- · Reporting person: Adage Capital Management, L.P. · Sole voting: 0 · Shared voting: 700,000 · Sole dispositive: 0 · Shared dispositive: 700,000 · SCHEDULE 13G, 2026-05-13
- · Holder: Panacea Innovation Limited · Percent: 16.1% · SCHEDULE 13D/A
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.
Layoffs on record: about 15 jobs, latest 2025-10-07 (layoff filings and notices).
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 |
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More on Atara Biotherapeutics, Inc. and the records around it.
Atara Biotherapeutics, Inc. elsewhere on the record
- Leadership changes Jun 2026
- Layoff notices Oct 2025
- Who owns it
Companies that share a holder
- Panacea Innovation Limited also filed stake reports on 3 other companies: Connect Biopharma Holdings Limited (Apr 2026), CASI Pharmaceuticals, Inc. (Dec 2025), Adagene Inc. (Nov 2025)
- Redmile Group, LLC also filed stake reports on 18 other companies: FATE THERAPEUTICS INC (Nov 2026), Electra Therapeutics, Inc. (Sep 2026), Neurogene Inc. (Aug 2026)
- EcoR1 Capital, LLC also filed stake reports on 20 other companies: Mereo BioPharma Group plc (Aug 2026), Alto Neuroscience, Inc. (Jul 2026), Fulcrum Therapeutics, Inc. (Jun 2026)
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Redmile Group, LLC | 0 | 950,994 | 0 | 950,994 | SCHEDULE 13D/A, 2026-07-24 |
| Green Jeremy | 0 | 950,994 | 0 | 950,994 | SCHEDULE 13D/A, 2026-07-24 |
| Redmile Biopharma Investments II, L.P. | 0 | 631,020 | 0 | 631,020 | SCHEDULE 13D/A, 2026-07-24 |
| Redmile Strategic Long Only Trading Sub, Ltd. | 0 | 401,901 | 0 | 401,901 | SCHEDULE 13D/A, 2026-07-24 |
| Adage Capital Management, L.P. | 0 | 700,000 | 0 | 700,000 | SCHEDULE 13G, 2026-05-13 |
| Robert Atchinson | 0 | 700,000 | 0 | 700,000 | SCHEDULE 13G, 2026-05-13 |
| Phillip Gross | 0 | 700,000 | 0 | 700,000 | SCHEDULE 13G, 2026-05-13 |
| Point72 Asset Management, L.P. | 0 | 687,718 | 0 | 687,718 | SCHEDULE 13G/A, 2026-08-14 |
| Point72 Capital Advisors, Inc. | 0 | 687,718 | 0 | 687,718 | SCHEDULE 13G/A, 2026-08-14 |
| Steven A. Cohen | 0 | 687,718 | 0 | 687,718 | SCHEDULE 13G/A, 2026-08-14 |
The latest filing identifies Atara Biotherapeutics, Inc. by CUSIP 046513206 and gives its principal executive office as 1280 RANCHO CONEJO BLVD, THOUSAND OAKS, CA 91320 (SCHEDULE 13G/A, 2026-08-14).
Source of funds (Item 3)
On July 16, 2026, Redmile Group, LLC ("Redmile") exercised certain Warrants held by RBI II and Redmile Long Only through a "cashless exercise" to acquire the Issuer's Common Stock. The transactions resulted in the Issuer (i) withholding 53 shares of Common Stock from RBI II and 7 shares of Common Stock from Redmile Long Only to pay the exercise price under the terms of the Warrants and (ii) issuing the remaining 174,247 shares of Common Stock to RBI II and 20,904 shares of Common Stock to Redmile Long Only.Redmile Group, LLC, SCHEDULE 13D/A, 2026-07-24
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 |
Questions about who owns Atara Biotherapeutics, Inc.
Who owns Atara Biotherapeutics, Inc.?
On this page, 5 holders' latest ownership filings report 5% or more of Atara Biotherapeutics, Inc.: EcoR1 Capital, LLC (17.4%, Schedule 13G/A, filed 2026-05-07), Panacea Innovation Limited (16.1%, Schedule 13D/A, filed 2026-05-11), Redmile Group, LLC (9.9%, Schedule 13D/A, filed 2026-07-24), Adage Capital Management, L.P. (8.56%, Schedule 13G, filed 2026-05-13) and Point72 Asset Management, L.P. (7.6%, Schedule 13G/A, filed 2026-08-14).
Who are the largest shareholders of Atara Biotherapeutics, Inc.?
By the share each holder's latest filing reports, the largest holders of Atara Biotherapeutics, Inc. on this page are EcoR1 Capital, LLC (17.4%), Panacea Innovation Limited (16.1%) and Redmile Group, LLC (9.9%).
When did EcoR1 Capital, LLC buy into Atara Biotherapeutics, Inc.?
The filings give report dates, not purchase dates. The earliest filing from EcoR1 Capital, LLC on this page is the Schedule 13G/A, filed 2025-11-14, reporting 9.9%; its latest, Schedule 13G/A filed 2026-05-07, reports 17.4%. That earliest filing is itself an amendment, which updates an earlier report.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 11 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
Also on the record for Atara Biotherapeutics, Inc.
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| June 26, 2026 | Leadership change: Kevin G. Sarney appointed | — | Leadership changes | Source |
| June 12, 2026 | Leadership change: Brian Cherry appointed, Director | — | Leadership changes | Source |
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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.