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: −$68.0K (12 inflow days, 8 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 64.8% of shares outstanding.
Reported short interest has risen from 5.19% to 5.88% of float over the last 6 biweekly reports (30 Jun 2026 to 15 Sep 2026).
| Holder | Type | Period | Share change | New stake |
|---|---|---|---|---|
| PureTech Health plc | Public Company | 2026/Q3 | +16,685,013 | 31.2% |
| Arch Venture Partners, L.P. | VC/PE Fund | 2026/Q3 | +6,294,951 | 11.8% |
| General Atlantic Service Company, L.P. | VC/PE Fund | 2026/Q3 | +6,101,582 | 11.4% |
| Sofinnova Investments, Inc. | VC/PE Fund | 2026/Q3 | +3,564,871 | 6.7% |
| Third Rock Ventures, LLC | VC/PE Fund | 2026/Q3 | +2,061,222 | 3.9% |
| Canada Pension Plan Investment Board | Government Pension Fund | 2026/Q3 | +1,975,791 | 3.7% |
| J.P. Morgan Asset Management, Inc. | Mutual Fund | 2026/Q3 | +1,785,104 | 3.3% |
| Foresite Capital Management, LLC | VC/PE Fund | 2026/Q3 | +1,779,521 | 3.3% |
| T. Rowe Price Group, Inc. | Mutual Fund | 2026/Q3 | +1,308,604 | 2.4% |
| The Goldman Sachs Group, Inc. | Public Company | 2026/Q3 | +1,194,858 | 2.2% |
| Daphne Zohar | Individual/Insider | 2026/Q3 | +1,194,001 | 2.2% |
| FMR | Mutual Fund | 2026/Q3 | +1,185,100 | 2.2% |
| Bellevue Asset Management AG | Mutual Fund | 2026/Q3 | +1,100,000 | 2.1% |
| Artal Group S.A. | VC/PE Fund | 2026/Q3 | +1,095,316 | 2.0% |
| Jennison Associates LLC | Mutual Fund | 2026/Q3 | +1,079,669 | 2.0% |
Institutional buy/sell activity by reporting period, largest moves first.
| Date | Insider | Title | Transaction | Shares | Price | Held after |
|---|---|---|---|---|---|---|
| 21 Jun 2026 | Robert Hombach | Independent Director | Open Market Acquisition | +13,000 | $18.14 | 13,000 |
| 3 May 2026 | General Atlantic Service Company, L.P. | Initial Statement of Beneficial | +0 | – | 6,101,582 | |
| 3 May 2026 | Steven Paul | Founder & Non-Employee Chair of the Board | Derivative Exercise and Retained | +67,031 | – | 863,031 |
| 3 May 2026 | PureTech Health plc | Derivative Exercise and Retained | +16,382,534 | – | 16,685,013 | |
| 3 May 2026 | Antony Loebel | Chief Medical Officer & President of Clinical Development | Derivative Exercise and Retained | +20,109 | – | 20,109 |
| 3 May 2026 | Denice Torres | Independent Director | Derivative Exercise and Retained | +13,406 | – | 13,406 |
| 3 May 2026 | Lana Gladstein | General Counsel | Derivative Exercise and Retained | +33,515 | – | 33,515 |
| 3 May 2026 | Lauren White | Chief Financial Officer | Derivative Exercise and Retained | +6,702 | – | 6,702 |
| 3 May 2026 | Michael Chen | Co-Founder & CSO | Derivative Exercise and Retained | +3,351 | – | 3,351 |
| 29 Apr 2026 | Sandra Peterson | Independent Director | Other Derivative Acquisition | +12,258 | $18.00 | 12,258 |
| 29 Apr 2026 | Sandra Peterson | Independent Director | Initial Statement of Beneficial | +0 | – | 89,300 |
| 29 Apr 2026 | Sharon Mates | Independent Director | Other Derivative Acquisition | +49,033 | $18.00 | 49,033 |
| 29 Apr 2026 | Steven Paul | Founder & Non-Employee Chair of the Board | Other Derivative Acquisition | +1,003,450 | $18.00 | 991,192 |
| 29 Apr 2026 | Steven Paul | Founder & Non-Employee Chair of the Board | Initial Statement of Beneficial | +0 | – | 1,674,753 |
| 29 Apr 2026 | PureTech Health plc | Initial Statement of Beneficial | +0 | – | 302,479 | |
| 29 Apr 2026 | Daphne Zohar | Chief Executive Officer | Other Derivative Acquisition | +1,758,599 | $18.00 | 1,486,786 |
| 29 Apr 2026 | Daphne Zohar | Chief Executive Officer | Initial Statement of Beneficial | +0 | – | 2,765,557 |
| 29 Apr 2026 | Robert Hombach | Independent Director | Other Derivative Acquisition | +12,258 | $18.00 | 12,258 |
| 29 Apr 2026 | Robert Hombach | Independent Director | Initial Statement of Beneficial | +0 | – | 89,300 |
| 29 Apr 2026 | David Wheadon | Independent Director | Other Derivative Acquisition | +12,258 | $18.00 | 12,258 |
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 | 3,148,881 | 5.9% | 20.7 |
| 31 Aug 2026 | 3,152,409 | 5.9% | 26.0 |
| 14 Aug 2026 | 3,012,877 | 5.6% | 25.1 |
| 31 Jul 2026 | 2,758,029 | 5.2% | 30.8 |
| 15 Jul 2026 | 1,980,276 | 3.7% | 12.3 |
| 30 Jun 2026 | 2,779,385 | 5.2% | 7.7 |
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