Form 4: Mersana CFO DeSchuytner Reports Share Disposition Post-Merger

Mersana Therapeutics' SVP, COO & CFO, Brian DeSchuytner, reported the disposition of common stock, stock options, and restricted stock units following the company's merger with Day One Biopharmaceuticals.

Summary

• Brian DeSchuytner, SVP, COO & CFO of Mersana Therapeutics, Inc., reported changes in his beneficial ownership of company securities.
• The changes occurred on January 6, 2026, as a result of the merger of Mersana Therapeutics, Inc. with Emerald Merger Sub, Inc., a wholly-owned subsidiary of Day One Biopharmaceuticals, Inc.
• Common stock shares were exchanged for $25.00 per share in upfront cash and one non-tradeable contingent value right (CVR) per share, with CVRs potentially yielding up to an additional $30.25 per CVR.
• Options with an exercise price less than $25.00 (Cash-Out Options) became fully vested and were converted into the right to receive the Offer Price minus their exercise price.
• Options with an exercise price equal to or greater than $25.00 (OTM Options) became fully vested and exercisable but were cancelled without consideration if not exercised by the Last Exercise Date.
• Restricted Stock Units (RSUs) were automatically cancelled and converted into the right to receive the Offer Price.
• DeSchuytner disposed of 5,015 shares of common stock, various stock options totaling 45,000 shares underlying options, and 5,300 restricted stock units.
• Following these transactions, DeSchuytner beneficially owns 0 shares of common stock and 0 derivative securities.
• The reported common stock includes 160 shares acquired through the Issuer's employee stock purchase plan in June 2025.

Sentiment

Score: 7

Explanation: The sentiment is moderately positive as the reporting person received upfront cash and potential future payments via CVRs for their equity holdings, reflecting a successful exit for the company's shareholders through the merger. However, the cancellation of out-of-the-money options without consideration introduces a minor negative aspect.

Positives

• The reporting person received $25.00 per share in cash for common stock and RSUs.
• The reporting person received one non-tradeable Contingent Value Right (CVR) per share, offering potential future payments of up to $30.25 per CVR.
• In-the-money stock options were cashed out based on the Offer Price minus their exercise price.

Negatives

• Out-of-the-money stock options were cancelled without any consideration if not exercised by the Last Exercise Date.

Risks

• The contingent value rights (CVRs) are non-tradeable, limiting liquidity.
• Payments from CVRs are contingent upon the achievement of certain specified milestones, meaning there is no guarantee of receiving the full $30.25 per CVR or any payment at all.

Future Outlook

The reporting person holds contingent value rights (CVRs) which represent the right to receive future contingent milestone payments of up to an aggregate of $30.25 per CVR, subject to the achievement of certain specified milestones.

Industry Context

This filing reflects the finalization of a merger transaction in the biotechnology or pharmaceutical sector, where a smaller company (Mersana Therapeutics) was acquired by a larger entity (Day One Biopharmaceuticals). Such acquisitions are common strategies for larger companies to expand their pipeline or market share, and for smaller companies to realize value for shareholders, often involving a mix of upfront cash and contingent value rights tied to future drug development milestones.

Related Party Transactions

• The disposition of securities by Brian DeSchuytner, an SVP, COO & CFO of Mersana Therapeutics, Inc., as part of the company's merger, constitutes a transaction involving a related party.

Stakeholder Impact

• Shareholders: Received $25.00 per share in upfront cash and one non-tradeable CVR per share, with potential for additional payments up to $30.25 per CVR.
• Employees (holding options/RSUs): Those with in-the-money options and RSUs received cash and CVRs based on the merger terms. Those with out-of-the-money options had them cancelled without consideration.

Next Steps

• Achievement of specified milestones for CVR payments.

Key Dates

Keywords

Mersana Therapeutics, MRSN, Day One Biopharmaceuticals, Merger, Form 4, Insider Transaction, Beneficial Ownership, Contingent Value Right, CVR, Stock Options, Restricted Stock Units, Executive Compensation