Mersana TherapeuticsMRSN
13F holders, Q4 2025 (December 31)At the end of Q4 2025, 48 institutions reported holding Mersana Therapeutics Inc. (MRSN) in their 13F filings, up 3 from Q3 2025. 17 opened new positions and 15 sold out. The largest holders were Nextech Invest Ltd. ($14.0M), Bain Capital Life Sciences Investors, LLC ($10.0M) and Vanguard Group Inc. ($6.1M). 5 famous investors held it, including Mario Gabelli (0.0% of GAMCO Investors'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 Q3 2025 → Q4 2025
| Institutions | Total Value | |
|---|---|---|
| New Positions | 17 | $13.0M |
| Exits | 15 | $5.8M |
All 13F filers, Q3 2025 → Q4 2025: 550,565 shares bought and 1,434,049 shares sold, net −883,484 shares. Counts holders who added, trimmed, opened or closed a position; split-adjusted.
Ownership 48 holders
| Nextech Invest Ltd. | 1.35% | No change | 482,689 | $14.0M |
| Bain Capital Life Sciences Investors, LLC | 0.77% | No change | 346,545 | $10.0M |
| Vanguard Group Inc. | 0.00% | Reduce -30.5% | 210,301 | $6.1M |
| Rock Springs Capital Management LP | 0.23% | No change | 152,586 | $4.4M |
| Alamea Verwaltungs GmbH | 2.25% | Reduce -94.4% | 24,165 | $3.3M |
| Acadian Asset Management LLC | 0.01% | Reduce -22.1% | 110,882 | $3.2M |
| Affinity Asset Advisors, LLC | 0.21% | New | 100,000 | $2.9M |
| BlackRock, Inc. | 0.00% | Reduce -28.1% | 69,210 | $2.0M |
| Bank of America Corp. | 0.00% | Reduce -1.0% | 65,749 | $1.9M |
| Millennium Management | 0.00% | Reduce -18.8% | 63,305 | $1.8M |
| Groupe la Francaise | 0.03% | New | 61,488 | $1.8M |
| Rangeley Capital, LLC | 1.44% | New | 57,098 | $1.7M |
| Gabelli Funds LLC | 0.01% | New | 47,300 | $1.4M |
| Geode Capital Management, LLC | 0.00% | Add +5.5% | 43,920 | $1.3M |
| Credit Industriel Et Commercial | 0.27% | New | 41,392 | $1.2M |
| AQR Capital Management | 0.00% | Reduce -20.2% | 37,264 | $1.1M |
| Mackenzie Financial Corp. | 0.00% | Reduce -29.3% | 33,834 | $967K |
| Yakira Capital Management, Inc. | 0.32% | New | 32,663 | $945K |
| Citadel Advisors | 0.00% | New | 22,493 | $651K |
| State Street Corp. | 0.00% | Reduce -34.5% | 19,543 | $565K |
| Morgan Stanley | 0.00% | Reduce -61.7% | 18,496 | $535K |
| Deltec Asset Management LLC | 0.09% | New | 18,000 | $521K |
| Knott David M Jr | 0.20% | New | 111,686 | $438K |
| Ieq Capital, LLC | 0.00% | Reduce -15.0% | 12,955 | $375K |
| XTX Topco Ltd | 0.01% | New | 11,948 | $346K |
| Point72 Asset Management | 0.00% | New | 10,364 | $300K |
| GAMCO Investors | 0.00% | New | 10,000 | $289K |
| Northern Trust Corp. | 0.00% | New | 8,586 | $248K |
| OMERS ADMINISTRATION Corp | 0.00% | New | 7,900 | $229K |
| Equitec Proprietary Markets, LLC | 0.79% | New | 5,593 | $162K |
| Cwm, LLC | 0.00% | Reduce -20.6% | 2,286 | $66K |
| BNP Paribas Financial Markets | 0.00% | Add +105.3% | 1,090 | $32K |
| Group One Trading LLC | 0.00% | Add +11.7% | 1,073 | $31K |
| Mint Tower Capital Management B.V. | 0.01% | New | 1,035 | $30K |
| Tower Research Capital LLC (TRC) | 0.00% | Reduce -75.9% | 376 | $11K |
| UBS Group AG | 0.00% | Reduce -97.4% | 221 | $6K |
| Royal Bank of Canada | 0.00% | Reduce -75.7% | 168 | $5K |
| JPMorgan Chase & Co. | 0.00% | Reduce -98.2% | 112 | $3K |
| Osaic Holdings, Inc. | 0.00% | No change | 103 | $3K |
| Lion Point Capital, LP | 0.01% | Reduce -99.6% | 100 | $3K |
| Flagship Harbor Advisors, LLC | 0.00% | New | 76 | $2K |
| SBI Securities Co., Ltd. | 0.00% | Reduce -1.9% | 53 | $2K |
| Wells Fargo & Company | 0.00% | Reduce -96.8% | 40 | $1K |
| Huntington National Bank | 0.00% | No change | 32 | $926 |
| SHP Wealth Management | 0.00% | — | 25 | $723 |
| FMR LLC | 0.00% | Reduce -99.8% | 8 | $231 |
| IFP Advisors, Inc | 0.00% | Reduce -40.0% | 3 | $87 |
| Danske Bank A/S | 0.00% | No change | 1 | $29 |
"% of holder's portfolio" is MRSN's weight in each manager's 13F, not the share of Mersana Therapeutics Inc. the manager owns.