| Filer | Ownership | Change % | Holdings Value | Net Change | Nb Shares | Change % | Reporting Name | Report Period |
|---|---|---|---|---|---|---|---|---|
| 683 Capital Management, LLC | 7% | +31% | $10,215,484 | +$2,264,431 | 351,289 | +28% | 683 Capital Management, LLC | 31 Dec 2025 |
| VANGUARD GROUP INC | 4.2% | $6,082,136 | 210,301 | The Vanguard Group | 31 Dec 2025 |
As of 31 Dec 2025, 46 institutional investors reported holding 2,118,875 shares of Mersana Therapeutics, Inc. - Common Stock, par value $0.0001 per share (MRSN). This represents 42% of the company’s total 4,996,999 outstanding shares.
The largest institutional shareholders of Mersana Therapeutics, Inc. - Common Stock, par value $0.0001 per share (MRSN) together control 42% of the company’s outstanding shares — a level of ownership often associated with strong institutional conviction and long‑term capital commitment.
| Institution | Ownership % | Shares Held | Share Change % | Portfolio % | Holdings Value |
|---|---|---|---|---|---|
| Nextech Invest, Ltd. | 9.7% | 482,689 | 0% | 1.3% | $13,964,193 |
| Bain Capital Life Sciences Investors, LLC | 6.9% | 346,545 | 0% | 0.77% | $10,025,547 |
| VANGUARD GROUP INC | 4.2% | 210,301 | -30% | 0% | $6,084,008 |
| Rock Springs Capital Management LP | 3.1% | 152,586 | 0% | 0.23% | $4,414,313 |
| ACADIAN ASSET MANAGEMENT LLC | 2.2% | 110,882 | -22% | 0.01% | $3,207,000 |
| Affinity Asset Advisors, LLC | 2% | 100,000 | 0.21% | $2,893,000 | |
| BlackRock, Inc. | 1.4% | 69,210 | -28% | 0% | $2,002,245 |
| BANK OF AMERICA CORP /DE/ | 1.3% | 65,749 | -0.98% | 0% | $1,902,119 |
| MILLENNIUM MANAGEMENT LLC | 1.3% | 63,305 | -19% | 0% | $1,831,414 |
| Groupe la Francaise | 1.2% | 61,488 | 0.03% | $1,778,848 | |
| Rangeley Capital, LLC | 1.1% | 57,098 | 1.4% | $1,651,845 | |
| GABELLI FUNDS LLC | 0.95% | 47,300 | 0.01% | $1,368,389 | |
| GEODE CAPITAL MANAGEMENT, LLC | 0.88% | 43,920 | +5.5% | 0% | $1,270,972 |
| CREDIT INDUSTRIEL ET COMMERCIAL | 0.83% | 41,392 | 0.17% | $1,197,471 | |
| AQR CAPITAL MANAGEMENT LLC | 0.75% | 37,264 | -20% | 0% | $1,078,047 |
| MACKENZIE FINANCIAL CORP | 0.68% | 33,834 | -29% | 0% | $967,437 |
| Yakira Capital Management, Inc. | 0.65% | 32,663 | 0.32% | $944,940 | |
| CITADEL ADVISORS LLC | 0.45% | 22,493 | 0% | $650,722 | |
| STATE STREET CORP | 0.39% | 19,543 | -35% | 0% | $565,379 |
| MORGAN STANLEY | 0.37% | 18,496 | -62% | 0% | $535,089 |
| DELTEC ASSET MANAGEMENT LLC | 0.36% | 18,000 | 0.09% | $520,740 | |
| IEQ CAPITAL, LLC | 0.26% | 12,955 | -15% | 0% | $374,788 |
| XTX Topco Ltd | 0.24% | 11,948 | 0.01% | $345,656 | |
| Point72 Asset Management, L.P. | 0.21% | 10,364 | 0% | $299,831 | |
| GAMCO INVESTORS, INC. ET AL | 0.2% | 10,000 | 0% | $289,300 |