Institutional HoldersBeta
Who holds a company, from every 13F filed for the quarter, one row per filer exactly as filed, against the latest share count the company reported.
Share classes (cover page of the 10-Q filed 2026-08-12, as of 2026-08-10)
| Class | Listed | Shares outstanding | Held by 13F filers | % of class | Holders | CUSIP |
|---|---|---|---|---|---|---|
| Common stock | ATRA · NASDAQ | 10,037,710 | 4,467,954 | 44.5% | 35 | 046513206 |
Each class is compared with its own share count; classes are not added together. A class that is not exchange-listed cannot be held by 13F filers.
Top holders (1 of 1 · 046513107)
change vs 2026-03-31| # | Filer | Shares / principal | % of class | Value | Change |
|---|---|---|---|---|---|
| 1 | PlanVest Financial, Inc | 28 | — | $321 | — |
Large holders from 13D/13G (latest per reporting person, last 2 years)
Filed when a holder crosses 5% or changes materially, so often more current than the quarter-end 13F. Percentages are the filer's own, against the share count they used.
| Reporting person | Form | Filed | Event | Shares | % of class |
|---|---|---|---|---|---|
| Steven A. Cohen | SCHEDULE 13G/A | 2026-08-14 | 2026-06-30 | 687,718 | 7.6% |
| Point72 Capital Advisors, Inc. | SCHEDULE 13G/A | 2026-08-14 | 2026-06-30 | 687,718 | 7.6% |
| Point72 Asset Management, L.P. | SCHEDULE 13G/A | 2026-08-14 | 2026-06-30 | 687,718 | 7.6% |
| Redmile Biopharma Investments II, L.P. | SCHEDULE 13D/A | 2026-07-24 | 2026-07-22 | 631,020 | 6.6% |
| Green Jeremy | SCHEDULE 13D/A | 2026-07-24 | 2026-07-22 | 950,994 | 9.9% |
| Redmile Strategic Long Only Trading Sub, Ltd. | SCHEDULE 13D/A | 2026-07-24 | 2026-07-22 | 401,901 | 4.2% |
| Redmile Group, LLC | SCHEDULE 13D/A | 2026-07-24 | 2026-07-22 | 950,994 | 9.9% |
| Jeremy C. Green | SCHEDULE 13D/A | 2026-05-14 | 2026-05-12 | 950,994 | 9.9% |
| Phillip Gross | SCHEDULE 13G | 2026-05-13 | 2026-03-31 | 700,000 | 8.56% |
| Adage Capital Management, L.P. | SCHEDULE 13G | 2026-05-13 | 2026-03-31 | 700,000 | 8.56% |
| Robert Atchinson | SCHEDULE 13G | 2026-05-13 | 2026-03-31 | 700,000 | 8.56% |
| Panacea Innovation Limited | SCHEDULE 13D/A | 2026-05-11 | 2026-05-07 | 1,318,894 | 16.1% |
| Panacea Opportunity Fund I GP Company, Ltd. | SCHEDULE 13D/A | 2026-05-11 | 2026-05-07 | 307,899 | 3.8% |
| Panacea Opportunity Fund I, L.P. | SCHEDULE 13D/A | 2026-05-11 | 2026-05-07 | 307,899 | 3.8% |
| Panacea Venture Healthcare Fund II GP Company, Ltd. | SCHEDULE 13D/A | 2026-05-11 | 2026-05-07 | 1,011,000 | 12.4% |
| Panacea Venture Healthcare Fund II, L.P. | SCHEDULE 13D/A | 2026-05-11 | 2026-05-07 | 1,011,000 | 12.4% |
| James Huang | SCHEDULE 13D/A | 2026-05-11 | 2026-05-07 | 1,318,894 | 16.1% |
| Oleg Nodelman | SCHEDULE 13G/A | 2026-05-07 | 2026-05-07 | 1,552,000 | 17.4% |
| EcoR1 Capital, LLC | SCHEDULE 13G/A | 2026-05-07 | 2026-05-07 | 1,552,000 | 17.4% |
| EcoR1 Capital Fund Qualified, L.P. | SCHEDULE 13G/A | 2026-05-07 | 2026-05-07 | 1,445,609 | 16.2% |
| RedCo I, L.P. | SCHEDULE 13D/A | 2025-11-14 | 2025-11-12 | 347,442 | 4.7% |
| Gregory A. Ciongoli | SCHEDULE 13D/A | 2025-05-16 | 2025-05-14 | 1,370,081 | 19.99% |
| Adiumentum Capital Fund I LP | SCHEDULE 13D/A | 2025-05-16 | 2025-05-14 | 1,370,081 | 19.99% |
| Adiumentum Capital Fund I GP LLC | SCHEDULE 13D/A | 2025-05-16 | 2025-05-14 | 1,370,081 | 19.99% |
Source: SEC Form 13F-HR information tables for the quarter ending 2026-06-30 (filed within 45 days of quarter end; amendments applied; values normalised to dollars), the share count from the company's latest 10-K/10-Q XBRL cover page, and Schedule 13D/13G filings. Each row is a legal 13F filer as filed — related entities (e.g. Vanguard's advisers) are not merged. Retail brokerage accounts are not reported on 13F, so the remainder is mostly retail and insiders.