Who holds it, who is betting against it, and where the big money is moving
Net of large-order buying minus selling, in USD. Over this window: +$475.8K (8 inflow days, 12 outflow days).
Super/Big orders approximate institutional-size trades; Mid/Small approximate retail-size trades. Net buy minus sell value in each bucket, summed over the window.
The five largest holders on file together own 52.1% of shares outstanding.
Reported short interest has fallen from 17.24% to 14.96% of float over the last 6 biweekly reports (30 Jun 2026 to 15 Sep 2026).
| Holder | Type | Period | Share change | New stake |
|---|---|---|---|---|
| MPM BioImpact LLC | VC/PE Fund | 2026/Q3 | +2,083,073 | 15.1% |
| T. Rowe Price Group, Inc. | Mutual Fund | 2026/Q3 | +1,796,231 | 5.9% |
| State Street Global Advisors | Mutual Fund | 2026/Q3 | +1,124,512 | 5.7% |
| BlackRock | Mutual Fund | 2026/Q3 | +782,800 | 8.1% |
| Boone Capital Management LLC | Hedge Fund | 2026/Q3 | +704,442 | 1.1% |
| Artal Group S.A. | VC/PE Fund | 2026/Q3 | +700,000 | 2.9% |
| RTW Investments, LP | Hedge Fund | 2026/Q3 | +658,387 | 3.7% |
| The Goldman Sachs Group, Inc. | Public Company | 2026/Q3 | +536,382 | 1.5% |
| Perceptive Advisors LLC | VC/PE Fund | 2026/Q3 | +426,478 | 0.7% |
| Adage Capital Management, L.P. | Hedge Fund | 2026/Q3 | +238,000 | 0.4% |
| FMR | Mutual Fund | 2026/Q3 | +232,980 | 0.4% |
| AQR Capital Management | Hedge Fund | 2026/Q3 | +219,436 | 0.9% |
| Vanguard Portfolio Management, LLC | Mutual Fund | 2026/Q3 | +186,188 | 1.1% |
| Geode Capital Management, LLC | Mutual Fund | 2026/Q3 | +179,041 | 2.4% |
| Squarepoint OPS LLC | Hedge Fund | 2026/Q3 | +168,117 | 0.3% |
Institutional buy/sell activity by reporting period, largest moves first.
| Date | Insider | Title | Transaction | Shares | Price | Held after |
|---|---|---|---|---|---|---|
| 7 Sep 2026 | Jennifer Michaelson | Chief Scientific Officer | Automatic Disposition | -4,000 | $21.57 | 158,844 |
| 7 Sep 2026 | Jennifer Michaelson | Chief Scientific Officer | Derivative Exercise and Sale | -4,000 | $21.57 | 158,844 |
| 12 Aug 2026 | Jennifer Michaelson | Chief Scientific Officer | Derivative Exercise and Sale | -30,000 | $20.26 | 162,844 |
| 5 Jul 2026 | Jennifer Michaelson | Chief Scientific Officer | Automatic Disposition | -4,000 | $17.82 | 162,844 |
| 5 Jul 2026 | Jennifer Michaelson | Chief Scientific Officer | Derivative Exercise and Sale | -4,000 | $17.82 | 162,844 |
| 29 Jun 2026 | Mary Fenton | Chief Financial Officer | Other Acquisition | +1,541 | $8.60 | 127,921 |
| 29 Jun 2026 | Jacquelyn Sumer | Chief Legal Officer, Chief Compliance Officer & Corporate Secretary | Other Acquisition | +2,470 | $8.60 | 60,226 |
| 15 Jun 2026 | Stephen Webster | Independent Director | Other Derivative Acquisition | +25,319 | $13.55 | 25,319 |
| 15 Jun 2026 | Anthony Rosenberg | Independent Chairperson | Other Derivative Acquisition | +25,319 | $13.55 | 25,319 |
| 15 Jun 2026 | Mary Thistle | Director | Other Derivative Acquisition | +25,319 | $13.55 | 25,319 |
| 15 Jun 2026 | Andrew Allen | Director | Other Derivative Acquisition | +21,781 | $13.55 | 21,781 |
| 15 Jun 2026 | David Meek | Independent Director | Other Derivative Acquisition | +25,319 | $13.55 | 25,319 |
| 15 Jun 2026 | Mittie Doyle | Director | Other Derivative Acquisition | +21,781 | $13.55 | 21,781 |
| 4 May 2026 | Jennifer Michaelson | Chief Scientific Officer | Automatic Disposition | -4,000 | $15.58 | 166,844 |
| 4 May 2026 | Jennifer Michaelson | Chief Scientific Officer | Derivative Exercise and Sale | -4,000 | $14.60 | 166,844 |
| 4 Mar 2026 | Jennifer Michaelson | Chief Scientific Officer | Automatic Disposition | -4,000 | $15.68 | 170,844 |
| 4 Mar 2026 | Jennifer Michaelson | Chief Scientific Officer | Derivative Exercise and Sale | -4,000 | $15.68 | 170,844 |
| 24 Feb 2026 | Jennifer Michaelson | Chief Scientific Officer | Automatic Disposition | -1,780 | $14.14 | 174,844 |
| 23 Feb 2026 | Jeffrey Jones | Chief Medical Officer | Open Market Disposition | -4,582 | $14.47 | 64,968 |
| 23 Feb 2026 | Nadim Ahmed | Chief Executive Officer | Open Market Disposition | -13,515 | $14.47 | 148,553 |
From Form 4/Form 144 filings. Negative share counts are disposals (sales, gifts, or shares withheld for taxes); positive are acquisitions.
| Report date | Shares short | % of float | Days to cover |
|---|---|---|---|
| 15 Sep 2026 | 9,629,017 | 15.0% | 10.9 |
| 31 Aug 2026 | 10,371,763 | 16.1% | 15.5 |
| 14 Aug 2026 | 10,588,430 | 16.5% | 15.5 |
| 31 Jul 2026 | 10,254,541 | 16.7% | 19.2 |
| 15 Jul 2026 | 10,285,963 | 16.7% | 15.2 |
| 30 Jun 2026 | 10,597,500 | 17.2% | 6.6 |
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