Merger cash and CVR terms for Mersana Therapeutics (NASDAQ: MRSN)

Rhea-AI Filing Summary

Mersana Therapeutics, Inc. was acquired by Day One Biopharmaceuticals, with shares of common stock tendered for $25.00 per share in cash plus one non-tradeable contingent value right (CVR) per share. Each CVR provides the right to receive up to an additional $30.25 in cash per CVR if specified milestones are met. The merger closed with the buyer’s subsidiary merging into Mersana on January 6, 2026, making Mersana a wholly owned subsidiary.

In connection with the merger, VP and Chief Accounting Officer Ashish Mandelia reported that 2,300 shares of common stock and all reported stock options and restricted stock units were either converted into the cash-and-CVR consideration or cancelled under the merger terms, leaving zero securities beneficially owned after the transactions.

Insights

Equity compensation analyst

Officer equity awards were cashed out or cancelled under the merger terms.

The filing shows how Mersana Therapeutics handled insider equity as it became a wholly owned subsidiary of Day One Biopharmaceuticals. Common shares tendered in the offer were exchanged for $25.00 in cash per share plus one CVR per share, with each CVR tied to potential contingent payments of up to $30.25 in cash, subject to milestone achievement.

Options with exercise prices below $25.00 per share became fully vested and were cancelled in exchange for the cash-and-CVR package minus the option exercise price. Options with exercise prices at or above $25.00 were temporarily exercisable and then cancelled with no payment if left unexercised. Outstanding restricted stock units were converted into the same cash-and-CVR consideration. As of the effective time on January 6, 2026, the reporting officer no longer beneficially owned Mersana securities.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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X

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Mandelia Ashish

(Last) (First) (Middle)

C/O MERSANA THERAPEUTICS, INC.

840 MEMORIAL DRIVE

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Mersana Therapeutics, Inc. [ MRSN ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	VP, Chief Accounting Officer

3. Date of Earliest Transaction (Month/Day/Year)
01/06/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	01/06/2026		U(1)(2)		2,300	D	(1)(2)	0	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (right to buy)	$16.0125	01/06/2026		D			1,687	(3)	(3)	Common Stock	1,687	(3)	0	D
Stock Option (right to buy)	$16.0125	01/06/2026		D			1,312	(3)	(3)	Common Stock	1,312	(3)	0	D
Stock Option (right to buy)	$99.75	01/06/2026		D			2,870	(4)	(4)	Common Stock	2,870	(4)	0	D
Stock Option (right to buy)	$154	01/06/2026		D			555	(4)	(4)	Common Stock	555	(4)	0	D
Stock Option (right to buy)	$154	01/06/2026		D			44	(4)	(4)	Common Stock	44	(4)	0	D
Stock Option (right to buy)	$527.25	01/06/2026		D			310	(4)	(4)	Common Stock	310	(4)	0	D
Stock Option (right to buy)	$527.25	01/06/2026		D			773	(4)	(4)	Common Stock	773	(4)	0	D
Stock Option (right to buy)	$157	01/06/2026		D			359	(4)	(4)	Common Stock	359	(4)	0	D
Stock Option (right to buy)	$157	01/06/2026		D			788	(4)	(4)	Common Stock	788	(4)	0	D
Stock Option (right to buy)	$151.5	01/06/2026		D			722	(4)	(4)	Common Stock	722	(4)	0	D
Stock Option (right to buy)	$151.5	01/06/2026		D			1,183	(4)	(4)	Common Stock	1,183	(4)	0	D
Stock Option (right to buy)	$75.5	01/06/2026		D			1,157	(4)	(4)	Common Stock	1,157	(4)	0	D
Stock Option (right to buy)	$75.5	01/06/2026		D			1,842	(4)	(4)	Common Stock	1,842	(4)	0	D
Restricted Stock Units	$0	01/06/2026		D			192	(5)	(5)	Common Stock	192	(5)	0	D
Restricted Stock Units	$0	01/06/2026		D			212	(5)	(5)	Common Stock	212	(5)	0	D
Restricted Stock Units	$0	01/06/2026		D			500	(5)	(5)	Common Stock	500	(5)	0	D
Restricted Stock Units	$0	01/06/2026		D			666	(5)	(5)	Common Stock	666	(5)	0	D

Explanation of Responses:

1. Pursuant to the terms of that certain Agreement and Plan of Merger (the "Merger Agreement"), by and among the Issuer, Day One Biopharmaceuticals, Inc. ("Parent") and Parent's direct wholly-owned subsidiary, Emerald Merger Sub, Inc. ("Purchaser"), dated as of November 12, 2025, the shares (the "Shares") of common stock, par value $0.0001 per share, of the Issuer (the "Common Stock") that were tendered to Purchaser prior to the expiration time of the Offer were exchanged for: (i) $25.00 per Share, net to the stockholder in cash, without interest and less any applicable tax withholding (the "Upfront Cash Consideration"), plus (ii) one non-tradeable contingent value right per Share (each, a "CVR"),

2. (continued from footnote 1) which represents the right to receive certain contingent milestone payments of up to an aggregate of $30.25 per CVR in cash, without interest and less any applicable tax withholding, upon the achievement of certain specified milestones in accordance with the terms and subject to the conditions of a contingent value rights agreement entered into by Parent and the rights agent (the Upfront Cash Consideration plus one CVR, collectively, the "Offer Price"). After completion of the tender offer, pursuant to the terms of the Merger Agreement, Purchaser merged with and into the Issuer, effective as of January 6, 2026 (the "Effective Time"), with the Issuer continuing as the surviving corporation and a wholly owned subsidiary of Parent.

3. Pursuant to the terms of the Merger Agreement, effective as of immediately prior to the Effective Time, each option to purchase shares of Common Stock ("Issuer Option") that was outstanding and unexercised as of immediately prior to the Effective Time and had an exercise price per Share that was less than the Upfront Cash Consideration (each, a "Cash-Out Option"), became fully vested and was automatically cancelled and converted into the right to receive, without interest and subject to deduction for any required tax withholding, (i) the Offer Price minus (ii) the exercise price payable per share of Common Stock underlying such Cash-Out Option.

4. Pursuant to the terms of the Merger Agreement, effective as of 10 business days prior to the closing of the Merger (the "Acceleration Date"), each Issuer Option then outstanding and unexercised that had an exercise price per Share that was equal to or greater than the Upfront Cash Consideration (each, an "OTM Option"), became fully vested and exercisable up to and through the closing of regular trading on the Nasdaq Stock Market on the fifth business day following the Acceleration Date (the "Last Exercise Date"). OTM Options not exercised on or prior to the Last Exercise Date were cancelled and ceased to exist as of the Effective Time, and no consideration was delivered in exchange for such OTM Option.

5. Pursuant to the terms of the Merger Agreement, effective as of immediately prior to the Effective Time, each Company restricted stock unit award, which represented the right to receive one share of Common Stock, that was then outstanding was automatically cancelled and converted into the right to receive, without interest and subject to deduction for any required tax withholding, the Offer Price.

	/s/ Ashish Mandelia	01/06/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
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FAQ

What does the Form 4 for Mersana Therapeutics (MRSN) disclose?

The Form 4 shows that officer Ashish Mandelia, VP and Chief Accounting Officer of Mersana Therapeutics, Inc., reported the disposition or cancellation of common stock, stock options, and restricted stock units on January 6, 2026 in connection with the company’s merger with Day One Biopharmaceuticals, Inc..

What consideration did Mersana Therapeutics shareholders receive in the merger?

Each share of Mersana common stock tendered was exchanged for $25.00 in cash per share, plus one non-tradeable contingent value right (CVR) per share. Each CVR represents the right to receive contingent milestone payments of up to an aggregate of $30.25 in cash, subject to specified milestones and conditions.

How were Mersana stock options treated under the merger agreement?

Options with an exercise price per share below the $25.00 cash amount became fully vested and were cancelled in exchange for the offer price minus the exercise price per underlying share. Options with exercise prices equal to or greater than $25.00 were vested and exercisable for a limited period before closing; any such options not exercised by the last exercise date were cancelled at the effective time with no consideration.

What happened to Mersana restricted stock units in the transaction?

Each outstanding restricted stock unit, representing a right to receive one share of common stock, was automatically cancelled immediately prior to the effective time and converted into the right to receive the same cash-and-CVR offer price, subject to tax withholding.

Does the reporting officer still own Mersana securities after the merger?

No. The Form 4 indicates that after the reported transactions on January 6, 2026, the reporting officer had zero common shares, stock options, or restricted stock units beneficially owned.

When did the Mersana and Day One Biopharmaceuticals merger become effective?

After completion of the tender offer, the buyer’s subsidiary merged with and into Mersana Therapeutics, Inc., with the merger effective as of January 6, 2026. Mersana continued as the surviving corporation and became a wholly owned subsidiary of Day One Biopharmaceuticals.