Mersana Therapeutics, Inc. has 11 Schedule 13D or 13G filings on record since 2025-07-17. No holder's latest filing reports 5% or more. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| The Vanguard Group | 4.2% | 210,301 | SCHEDULE 13G/A, 2026-01-30 | 2025-12-31 |
| BlackRock, Inc. | 3% | 3,761,876 | SCHEDULE 13G/A, 2025-07-17 | 2025-06-30 |
| Schonfeld Strategic Advisors LLC | 0% | 0 | SCHEDULE 13G/A, 2026-02-17 | 2025-12-31 |
| Bain Capital Life Sciences Fund II, L.P. | 0% | 0 | SCHEDULE 13D/A, 2026-01-08 | 2026-01-06 |
| 683 Capital Management, LLC | 0% | 0 | SCHEDULE 13G/A, 2026-05-15 | 2026-03-31 |
| Nextech Crossover I GP S.a. r.l. | 0% | 0 | SCHEDULE 13G/A, 2026-01-09 | 2026-01-06 |
Purpose of Transaction (Item 4)
Bain Capital Life Sciences Fund II, L.P.
Item 4 of the Initial Statement is hereby amended and supplemented to add the following: As previously disclosed, on November 12, 2025 the Issuer entered into an Agreement and Plan of Merger (the "Merger Agreement") by and among the Issuer, Day One Biopharmaceuticals, Inc. ("Parent"), and Emerald Merger Sub, Inc., a direct, wholly owned subsidiary of Parent ("Purchaser"), pursuant to which, on December 5, 2025, Purchaser commenced a tender offer (the "Offer") to acquire all of the issued and outstanding shares of the Issuer for (i) $25.00 per Share, net to the stockholder in cash without interest and less any applicable tax withholding, plus (ii) one non-tradeable contingent value right per share, which represents the right to receive certain contingent milestone payments of up to an aggregate of $30.25 per share in cash, without interest and less any applicable tax withholding (collectively, the "Offer Price"). On January 6, 2026, Purchaser irrevocably accepted for payment the shares of the Issuer's Common Stock that were validly tendered and not validly withdrawn pursuant to the Offer and, following the consummation of the Offer, pursuant to the terms and conditions of the Merger Agreement, on January 6, 2026, Purchaser was merged with and into the Issuer (the "Merger"), with the Issuer surviving the Merger as a direct wholly-owned subsidiary of Parent. Dr. Hack resigned as a director of the Issuer effective as of the effective time of the Merger (the "Effective Time").Item 4 of the SCHEDULE 13D/A filed 2026-01-08
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-07-17 | BlackRock, Inc. | 3% | SCHEDULE 13G/A |
| 2025-08-14 | Schonfeld Strategic Advisors LLC | 4.55% | SCHEDULE 13G/A |
| 2025-11-13 | Bain Capital Life Sciences Fund II, L.P. | 4% | SCHEDULE 13D/A |
| 2025-11-14 | Schonfeld Strategic Advisors LLC | 5.48% | SCHEDULE 13G |
| 2025-11-24 | 683 Capital Management, LLC | 5.47% | SCHEDULE 13G |
| 2026-01-08 | Bain Capital Life Sciences Fund II, L.P. | 0% | SCHEDULE 13D/A |
| 2026-01-09 | Nextech Crossover I GP S.a. r.l. | 0% | SCHEDULE 13G/A |
| 2026-01-30 | The Vanguard Group | 4.2% | SCHEDULE 13G/A |
| 2026-02-17 | Schonfeld Strategic Advisors LLC | 0% | SCHEDULE 13G/A |
| 2026-02-17 | 683 Capital Management, LLC | 7.03% | SCHEDULE 13G/A |
| 2026-05-15 | 683 Capital Management, LLC | 0% | SCHEDULE 13G/A |
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.