Every 8-K that Mersana Therapeutics, Inc. (MRSN) has filed with the SEC in the last 24 months is listed below, newest first, and each one links through to the document itself with the summary and the scores our analysis gives it.
A 8-K covers material events a company has to report between its quarterly reports, so if you follow MRSN and want that one kind of document rather than the whole filing history, this is the page to keep. The company's other filings, of every form, are on the full MRSN filings page.
Mersana Therapeutics, Inc. reports that it has been acquired by Day One Biopharmaceuticals, Inc. through a completed tender offer and follow-on merger. Stockholders who tendered their shares receive $25.00 in cash per share, plus one contingent value right (CVR) per share, which can pay up to an additional $30.25 per share in cash if specified milestones are achieved. The tender offer, which expired on January 5, 2026, resulted in 3,029,135 shares being validly tendered, representing about 60.57% of outstanding shares, satisfying the minimum condition. Following a short-form merger under Delaware law on January 6, 2026, Mersana became a wholly owned subsidiary of Day One, its common stock trading on Nasdaq was suspended, and the company is being delisted and deregistered as a public company. Mersana also terminated its at-the-market sales agreement and all stock incentive and employee stock purchase plans, and its prior board and officers were replaced by designees from the acquirer.
Mersana Therapeutics, Inc. filed a current report stating that it issued a press release with business updates and financial results for the fiscal quarter ended September 30, 2025. The company’s common stock trades on The Nasdaq Stock Market under the symbol MRSN. The press release is included as Exhibit 99.1, while Exhibit 104 covers the interactive data for the cover page. The company notes that the information in this earnings-related item and the attached exhibit is being furnished, not filed, which limits its exposure to certain Exchange Act liabilities and controls how it may be incorporated by reference into other SEC documents.
Mersana Therapeutics entered a definitive agreement to be acquired by Day One Biopharmaceuticals via a tender offer. Holders of Mersana common stock will be offered $25.00 in cash per share, plus one CVR per share that may pay up to an additional $30.25 per share upon achieving specified milestones. The offer will remain open for 20 business days, subject to extension.
Completion requires that more than 50% of outstanding shares (by one share) are tendered (the Minimum Condition), HSR clearance, accuracy of representations and compliance with covenants; there is no financing condition. After the offer, a short-form merger under DGCL 251(h) would close, with all remaining shares converted into the same consideration. Closing is expected by the end of January 2026, subject to conditions. A termination fee of $5.6 million may be payable in specified circumstances. Support agreements cover approximately 8.5% of shares as of November 10, 2025. CVRs are non-transferable (with limited exceptions) and carry no voting or dividend rights.
Mersana Therapeutics, Inc. reported that Nasdaq has notified the company it is not in compliance with Nasdaq Listing Rule 5450(b)(2)(A), which requires a minimum Market Value of Listed Securities of $50.0 million. This is a deficiency notice only and does not immediately affect the listing of Mersana’s common stock, which continues to trade on the Nasdaq Global Select Market under the symbol MRSN.
The company has 180 calendar days, until March 4, 2026, to regain compliance by having its market value close at or above $50.0 million for at least ten consecutive business days before that date. If Mersana does not regain compliance by the deadline, its securities would be subject to delisting, though it would have the right to appeal to a Nasdaq hearings panel. Mersana plans to monitor its market value and consider available options to address the issue, while noting there is no assurance it will regain or maintain compliance with Nasdaq rules.
Mersana Therapeutics announced a press release reporting business updates and financial results for the quarter ended June 30, 2025. The filing states the press release is furnished under Item 2.02 and that this furnished information, including Exhibit 99.1, is not to be deemed "filed" for purposes of Section 18 of the Exchange Act and is not incorporated by reference into other SEC filings except where specifically stated.
The Form 8-K lists Exhibit 99.1 (the press release) and Exhibit 104 (cover page interactive data) and is signed by the company’s Chief Financial Officer and Chief Operating Officer.
Mersana Therapeutics, Inc. (MRSN) has filed an 8-K disclosing that it will implement a 1-for-25 reverse stock split, effective 5:00 p.m. ET on 25 Jul 2025. Each block of 25 outstanding common shares will be reclassified into one share; fractional shares will be cashed out. The maneuver does not alter the company’s authorized share count or par value, but all equity incentive plan share pools and outstanding awards will be proportionally adjusted.
The reverse split is intended to restore compliance with Nasdaq’s $1.00 minimum bid price requirement, which the company previously flagged in its 2025 proxy. Post-split trading will commence on 28 Jul 2025 under the existing ticker “MRSN” with a new CUSIP of 59045L205.
No other material events, financial results or changes in fiscal year were reported. A copy of the Certificate of Amendment is attached as Exhibit 3.1.