Welcome to our dedicated page for Mersana Therapeutics SEC filings (Ticker: MRSN), a comprehensive resource for investors and traders seeking official regulatory documents including 10-K annual reports, 10-Q quarterly earnings, 8-K material events, and insider trading forms.
The Mersana Therapeutics, Inc. (MRSN) SEC filings page on Stock Titan provides access to the company’s regulatory disclosures as filed with the U.S. Securities and Exchange Commission. Mersana, a clinical-stage biopharmaceutical company focused on antibody-drug conjugates (ADCs), uses current reports on Form 8-K and other SEC filings to communicate material events, financial results, capital structure changes and transaction agreements.
Recent Form 8-K filings include disclosures about quarterly financial results and business updates, which are furnished under Item 2.02 and accompanied by press release exhibits. Other 8-Ks describe corporate actions such as the 1-for-25 reverse stock split of Mersana’s common stock, implemented via a Certificate of Amendment to its certificate of incorporation, and the resulting trading of MRSN on a post-split basis. The company has also filed an 8-K detailing a Nasdaq notice regarding non-compliance with the Market Value of Listed Securities requirement, explaining the compliance period and potential consequences if the deficiency is not cured.
A key 8-K filing outlines Mersana’s entry into an Agreement and Plan of Merger with Day One Biopharmaceuticals, Inc. and a wholly owned subsidiary. This document summarizes the planned tender offer for all outstanding Mersana shares, the structure of the cash consideration and contingent value rights, the subsequent merger mechanics and the conditions required to close the transaction. Additional 8-K disclosure describes the repayment and termination of a prior loan and security agreement, documenting the payoff amount and the discharge of related obligations.
On Stock Titan, these filings are supplemented by AI-powered summaries that highlight the main points of each document, helping users quickly understand items such as reverse stock split details, listing notices, merger terms and financing changes. Investors can review Forms 8-K alongside other periodic reports like 10-K and 10-Q (when available through EDGAR) to follow Mersana’s financial reporting, capital structure developments and the regulatory steps associated with its proposed acquisition by Day One. Real-time updates ensure new filings, including any future Form 4 insider transaction reports or proxy materials related to corporate actions, are captured as they are posted to the SEC’s system.
Mersana Therapeutics, Inc. received an amended Schedule 13G from Schonfeld Strategic Advisors LLC reporting that it no longer beneficially owns any of the company’s common stock. Schonfeld reports ownership of 0 shares, representing 0% of the outstanding common stock, with no sole or shared voting or dispositive power.
Schonfeld describes itself as an investment adviser to several private funds and separately managed accounts, and notes that its clients were the record owners of the securities previously covered. The amendment confirms that Schonfeld’s beneficial ownership has fallen to 5% or less of Mersana’s common stock.
Mersana Therapeutics, Inc. reported that investment entities associated with 683 Capital have filed an amended Schedule 13G/A regarding their ownership of its common stock. As of December 31, 2025, 683 Capital Partners, LP beneficially owned 351,289 shares of common stock.
This stake represents approximately 7.03% of Mersana’s outstanding common shares, based on 4,998,750 shares outstanding as of November 7, 2025 as disclosed in the company’s Form 10-Q. The filing states the securities are not held for the purpose of changing or influencing control of the company.
The Vanguard Group filed an amended Schedule 13G/A reporting its beneficial ownership in Mersana Therapeutics Inc. common stock as of 12/31/2025. Vanguard reports beneficial ownership of 210,301 shares, representing 4.2% of the outstanding common stock.
Vanguard reports no sole voting or dispositive power, with 26,367 shares subject to shared voting power and 210,301 shares subject to shared dispositive power. The filing states the securities are held in the ordinary course of business and not for the purpose of changing or influencing control of Mersana.
The document notes an internal realignment at Vanguard effective 01/12/2026, after which certain subsidiaries or business divisions that are deemed to have beneficial ownership will report on a disaggregated basis. Vanguard’s clients, including registered investment companies and other managed accounts, have the right to receive dividends and sale proceeds, but no single other person has an interest of more than 5%.
Mersana Therapeutics, Inc. attracted an updated ownership filing showing that a former significant holder now reports no stake in the company’s common stock. A group of reporting persons — Nextech Crossover I SCSp, Nextech Crossover I GP S.a. r.l., Ian Charoub, Costas Constantinides, and Rocco Sgobbo — each report beneficial ownership of 0.00 shares of Mersana’s common stock, representing 0.0% of the class as of the event date of January 6, 2026.
The filing is an Amendment No. 3 to a Schedule 13G and confirms that each reporting person now owns 5% or less of Mersana’s outstanding common stock. The filers also certify that the securities referenced were not acquired and are not held for the purpose of changing or influencing control of Mersana Therapeutics, but instead are not related to any control-seeking transaction.
Bain Capital Life Sciences-affiliated funds have fully exited their stake in Mersana Therapeutics, Inc. following its sale to Day One Biopharmaceuticals. This Schedule 13D amendment reports that Bain Capital Life Sciences Fund II, L.P., BCIP Life Sciences Associates, LP and BCLS II Investco, LP now beneficially own 0 shares of Mersana common stock, representing 0% of the class.
The change follows a tender offer and merger under which Day One’s subsidiary acquired all outstanding Mersana shares for $25.00 per share in cash plus one non-tradeable contingent value right per share, providing potential contingent milestone payments of up to an additional $30.25 per share in cash. The tender offer was accepted and the merger closed on January 6, 2026, with Mersana becoming a wholly owned subsidiary of Day One and its Bain-affiliated board representative, Dr. Andrew Hack, resigning at the merger’s effective time.
Mersana Therapeutics, Inc. director Andrew Hack reported changes in his holdings tied to the company’s acquisition by Day One Biopharmaceuticals. Under the merger agreement, each share of Mersana common stock tendered before the offer deadline was exchanged for $25.00 in cash per share plus one contingent value right, which may pay up to an additional $30.25 in cash per CVR if specified milestones are met. As of January 6, 2026, when the merger became effective and Mersana became a wholly owned subsidiary of Day One, Hack’s direct holding of 578 common shares and indirect interest in 346,545 shares held by Bain Capital Life Sciences entities were reported as affected by this exchange. Multiple stock options to buy Mersana common stock were also reported as disposed of with zero options remaining following the merger-related treatment of in-the-money and out-of-the-money awards.
Mersana Therapeutics director Allene Diaz reported the disposition of her remaining equity in connection with the acquisition of Mersana by Day One Biopharmaceuticals. Common shares of Mersana were exchanged for $25.00 per share in cash plus one non-tradeable contingent value right (CVR) per share. Each CVR entitles holders to potential milestone payments of up to an aggregate $30.25 per CVR, subject to specified milestones.
Under the merger agreement, vested stock options with exercise prices below $25.00 per share were cancelled and converted into the right to receive the cash-and-CVR offer value minus the option exercise price, while options with exercise prices at or above $25.00 per share became fully vested for a limited period and were cancelled at closing if not exercised, with no consideration paid. Following these transactions, Diaz reported 0 shares and 0 stock options beneficially owned.
Mersana Therapeutics director Willard H. Dere reported changes in his holdings following the completion of a merger in which Mersana became a wholly owned subsidiary of Day One Biopharmaceuticals. Each share of Mersana common stock tendered in the offer was exchanged for $25.00 in cash per share plus one contingent value right (CVR) per share, with the CVR providing for potential milestone payments of up to $30.25 per CVR in cash. In connection with the merger’s effective time on January 6, 2026, Dere’s 1,567 shares of common stock and multiple stock options were either cashed out or cancelled in accordance with the merger agreement mechanics, leaving him with no reported remaining Mersana equity.
Mersana Therapeutics insider Alejandra Carvajal, SVP and Chief Legal Officer, reported automatic changes to her equity holdings following the company’s acquisition by Day One Biopharmaceuticals. Common shares tendered in the offer were exchanged for $25.00 per share in cash plus one contingent value right, which can pay up to an additional $30.25 per share if specified milestones are met. After the tender offer, Emerald Merger Sub merged into Mersana, making Mersana a wholly owned subsidiary of Day One.
Under the merger agreement, vested in-the-money stock options were cancelled in return for the cash-and-CVR offer price minus the option exercise price. Out-of-the-money options became fully vested shortly before closing but expired without payment if not exercised by the last exercise date. All outstanding restricted stock units were cancelled and converted into the right to receive the same offer price as common shares.