Mersana TherapeuticsMRSN
13F holders, Q3 2025 (September 30)At the end of Q3 2025, 45 institutions reported holding Mersana Therapeutics Inc. (MRSN) in their 13F filings, up 43 from Q2 2025. 8 opened new positions and 1 sold out. The largest holders were Nextech Invest Ltd. ($3.7M), Alamea Verwaltungs GmbH ($3.3M) and Bain Capital Life Sciences Investors, LLC ($2.7M). 3 famous investors held it, including Jim Simons / Peter Brown (0.0% of Renaissance Technologies's portfolio), Israel Englander (0.0% of Millennium Management's portfolio) and Cliff Asness (0.0% of AQR Capital Management's portfolio).
- Company
- Mersana Therapeutics Inc.
- CUSIP
- 59045L205
- Latest filing quarter
- Q1 2026
History
Number of 13F holders
Total Exit/New Position Q2 2025 → Q3 2025
| Institutions | Total Value | |
|---|---|---|
| New Positions | 8 | $605K |
| Exits | 1 | $68K |
All 13F filers, Q2 2025 → Q3 2025: 700,704 shares bought and 516,367 shares sold, net +184,337 shares. Counts holders who added, trimmed, opened or closed a position; split-adjusted.
Ownership 45 holders
| Nextech Invest Ltd. | 0.57% | No change | 482,689 | $3.7M |
| Alamea Verwaltungs GmbH | 2.28% | Add +1679.3% | 430,025 | $3.3M |
| Bain Capital Life Sciences Investors, LLC | 0.18% | No change | 346,545 | $2.7M |
| Vanguard Group Inc. | 0.00% | Reduce -1.5% | 302,553 | $2.3M |
| Schonfeld Strategic Advisors LLC | 0.01% | Add +20.5% | 273,579 | $2.1M |
| Rock Springs Capital Management LP | 0.07% | No change | 152,586 | $1.2M |
| Acadian Asset Management LLC | 0.00% | Add +20.4% | 142,360 | $1.1M |
| Silverarc Capital Management, LLC | 0.15% | Add +6.8% | 133,636 | $1.0M |
| 683 Capital Management, LLC | 0.07% | Add +25.6% | 100,000 | $776K |
| BlackRock, Inc. | 0.00% | Reduce -36.1% | 96,193 | $746K |
| Renaissance Technologies | 0.00% | Reduce -22.4% | 88,465 | $686K |
| Millennium Management | 0.00% | Reduce -6.7% | 77,989 | $605K |
| Bank of America Corp. | 0.00% | Add +8165.3% | 66,397 | $515K |
| 5AM Venture Management, LLC | 0.15% | No change | 52,200 | $405K |
| Morgan Stanley | 0.00% | Add +237.9% | 48,327 | $375K |
| Mackenzie Financial Corp. | 0.00% | New | 47,819 | $371K |
| AQR Capital Management | 0.00% | Reduce -77.2% | 46,720 | $363K |
| Geode Capital Management, LLC | 0.00% | Reduce -0.8% | 41,648 | $323K |
| Two Sigma Advisers, LP | 0.00% | Add +8.4% | 40,640 | $315K |
| Two Sigma Investments, LP | 0.00% | Reduce -6.8% | 30,688 | $238K |
| State Street Corp. | 0.00% | Add +65.0% | 29,843 | $232K |
| Lion Point Capital, LP | 1.14% | No change | 25,760 | $200K |
| Ieq Capital, LLC | 0.00% | Reduce -40.3% | 15,240 | $118K |
| DRW Securities, LLC | 0.01% | New | 13,851 | $107K |
| Voleon Capital Management LP | 0.00% | New | 13,200 | $102K |
| UBS Group AG | 0.00% | Reduce -72.3% | 8,609 | $67K |
| JPMorgan Chase & Co. | 0.00% | Add +17.4% | 6,108 | $47K |
| FMR LLC | 0.00% | Reduce -12.2% | 4,864 | $38K |
| Cwm, LLC | 0.00% | New | 2,878 | $22K |
| Tower Research Capital LLC (TRC) | 0.00% | Add +23.3% | 1,562 | $12K |
| Wells Fargo & Company | 0.00% | Add +34.7% | 1,240 | $10K |
| Group One Trading LLC | 0.00% | Reduce -31.1% | 961 | $7K |
| China Universal Asset Management Co., Ltd. | 0.00% | Reduce -12.6% | 875 | $7K |
| Royal Bank of Canada | 0.00% | Add +11433.3% | 692 | $5K |
| BNP Paribas Financial Markets | 0.00% | Add +380.1% | 531 | $4K |
| Barclays PLC | 0.00% | Reduce -49.3% | 198 | $2K |
| Mirae Asset Global Investments Co., Ltd. | 0.00% | Add +0.2% | 193 | $1K |
| Arax Advisory Partners | 0.00% | New | 157 | $1K |
| Citigroup Inc. | 0.00% | Reduce -96.4% | 106 | $823 |
| Osaic Holdings, Inc. | 0.00% | New | 103 | $755 |
| GF Fund Management Co. LTD. | 0.00% | Reduce -9.4% | 94 | $729 |
| SBI Securities Co., Ltd. | 0.00% | Reduce -96.0% | 54 | $419 |
| Huntington National Bank | 0.00% | No change | 32 | $248 |
| IFP Advisors, Inc | 0.00% | New | 5 | $39 |
| Danske Bank A/S | 0.00% | New | 1 | $8 |
"% of holder's portfolio" is MRSN's weight in each manager's 13F, not the share of Mersana Therapeutics Inc. the manager owns.