Mohan Bala - 06 Jan 2026 Form 4 Insider Report for Mersana Therapeutics, Inc. (MRSN)

Signature
/s/ Mohan Bala
Issuer symbol
MRSN
Transactions as of
06 Jan 2026
Net transactions value
$0
Form type
4
Filing time
06 Jan 2026, 16:49:49 UTC
Previous filing
28 Oct 2025

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
Bala Mohan SVP, Chief Development C/O MERSANA THERAPEUTICS, INC., 840 MEMORIAL DRIVE, CAMBRIDGE /s/ Mohan Bala 06 Jan 2026 0001991787

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction MRSN Common Stock Disposition pursuant to a tender of shares in a change of control transaction -2,927 -100% 0 06 Jan 2026 Direct F1, F2

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction MRSN Stock Option (right to buy) Disposed to Issuer -3,515 -100% 0 06 Jan 2026 Common Stock 3,515 $16.01 Direct F3
transaction MRSN Stock Option (right to buy) Disposed to Issuer -7,734 -100% 0 06 Jan 2026 Common Stock 7,734 $16.01 Direct F3
transaction MRSN Stock Option (right to buy) Disposed to Issuer -1,853 -100% 0 06 Jan 2026 Common Stock 1,853 $215.75 Direct F4
transaction MRSN Stock Option (right to buy) Disposed to Issuer -2,646 -100% 0 06 Jan 2026 Common Stock 2,646 $215.75 Direct F4
transaction MRSN Stock Option (right to buy) Disposed to Issuer -1,053 -100% 0 06 Jan 2026 Common Stock 1,053 $151.50 Direct F4
transaction MRSN Stock Option (right to buy) Disposed to Issuer -5,246 -100% 0 06 Jan 2026 Common Stock 5,246 $151.50 Direct F4
transaction MRSN Stock Option (right to buy) Disposed to Issuer -1,190 -100% 0 06 Jan 2026 Common Stock 1,190 $75.50 Direct F4
transaction MRSN Stock Option (right to buy) Disposed to Issuer -9,309 -100% 0 06 Jan 2026 Common Stock 9,309 $75.50 Direct F4
transaction MRSN Restricted Stock Units Disposed to Issuer -700 -100% 0 06 Jan 2026 Common Stock 700 $0.000000 Direct F5
transaction MRSN Restricted Stock Units Disposed to Issuer -1,750 -100% 0 06 Jan 2026 Common Stock 1,750 $0.000000 Direct F5
transaction MRSN Restricted Stock Units Disposed to Issuer -2,500 -100% 0 06 Jan 2026 Common Stock 2,500 $0.000000 Direct F5
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Mohan Bala is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may continue.

Explanation of Responses:

Id Content
F1 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"),
F2 (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.
F3 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.
F4 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.
F5 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.