Ashish Mandelia - 13 Jan 2024 Form 4/A Insider Report for Mersana Therapeutics, Inc. (MRSN)

Role: VP, Chief Accounting Officer
Signature: /s/ Alejandra Carvajal, Attorney-in-Fact
Issuer symbol: MRSN
Transactions as of: 13 Jan 2024
Net transactions value: $0
Form type: 4/A
Filing time: 16 Feb 2024, 16:30:40 UTC
Date Of Original Report: 17 Jan 2024
Previous filing: 07 Sep 2023
Next filing: 07 Oct 2024
SEC: View on sec.gov

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
holding	MRSN	Common Stock						25,973	13 Jan 2024	Direct	F1

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Buy Plan / Sale Plan: These are also open market purchases/sales of shares, but in this case the transaction is part of a trading plan. Rule 10b5-1 allows insiders to setup a trading plan to buy/sell stocks over a certain period of time. Since the purchases/sales are predetermined, this protects the insiders from violating insider trading law.

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).

Explanation of Responses:

Id	Content
F1	On January 17, 2024, the Reporting Person filed a Form 4 reporting the vesting of restricted stock units ("RSU"s) between January 13, 2024 and January 15, 2024 and the sale of shares of common stock on January 16, 2024 to satisfy the Reporting Person's tax withholding obligations in connection with the service-based vesting and settlement of the RSUs (the "Original Form 4"). Due to an inadvertent arithmetic error, the number of shares beneficially owned by the Reporting Person following the receipt of the RSUs that vested on January 13, 2024 was incorrectly reported, which error also impacted the beneficial ownership figures reported following the subsequent transactions reported in the Original Form 4. This Form 4/A is being filed to correct the number of shares held by the Reporting Person as of January 16, 2024 after all transactions reported in the Original Form 4.

Content

On January 17, 2024, the Reporting Person filed a Form 4 reporting the vesting of restricted stock units ("RSU"s) between January 13, 2024 and January 15, 2024 and the sale of shares of common stock on January 16, 2024 to satisfy the Reporting Person's tax withholding obligations in connection with the service-based vesting and settlement of the RSUs (the "Original Form 4"). Due to an inadvertent arithmetic error, the number of shares beneficially owned by the Reporting Person following the receipt of the RSUs that vested on January 13, 2024 was incorrectly reported, which error also impacted the beneficial ownership figures reported following the subsequent transactions reported in the Original Form 4. This Form 4/A is being filed to correct the number of shares held by the Reporting Person as of January 16, 2024 after all transactions reported in the Original Form 4.