Mersana Therapeutics, Inc. — Director's Dealing 2021

Dec 2, 2021

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Mersana Therapeutics, Inc. (MRSN)
CIK: 0001442836
Period of Report: 2021-11-30

Reporting Person: Yang Arvin (Chief Medical Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2021-11-30	Common Stock	M	18500	—	Acquired	18500	Direct
2021-12-01	Common Stock	S	5527	$6.81	Disposed	12973	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2021-11-30	Restricted Stock Units	$	M	18500	Disposed		Common Stock (18500)	Direct

Footnotes

F1: Each restricted stock unit ("RSU") represents a contingent right to receive one share of the Issuer's common stock upon settlement.

F2: Represents the number of shares sold by the reporting person to cover tax withholding obligations in connection with the vesting of the RSUs listed in Table II. These sales were mandated by the Issuer's election under its equity incentive plans to require the reporting person to sell a number of shares of common stock needed to satisfy his tax withholding obligations and does not represent a discretionary trade by the reporting person.

F3: The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $6.68 to $7.00, inclusive. The reporting person undertakes to provide to Mersana Therapeutics, Inc., any security holder of Mersana Therapeutics, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (3) to this Form 4.

F4: 50% of the total number of RSUs vested on November 30, 2021, and the remainder of the total number of RSUs shall vest on November 30, 2022.