Mersana Therapeutics, Inc. — Director's Dealing 2021

Feb 24, 2021

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Mersana Therapeutics, Inc. (MRSN)
CIK: 0001442836
Period of Report: 2021-02-22

Reporting Person: Lowinger Timothy B (Chief Science & Tech. Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2021-02-22	Common Stock	M	1874	$3.51	Acquired	33318	Direct
2021-02-22	Common Stock	S	1874	$20.01	Disposed	31444	Direct
2021-02-22	Common Stock	M	2227	$6.16	Acquired	33671	Direct
2021-02-22	Common Stock	S	2227	$20.01	Disposed	31444	Direct
2021-02-22	Common Stock	M	1875	$3.51	Acquired	33319	Direct
2021-02-22	Common Stock	S	1875	$20.01	Disposed	31444	Direct
2021-02-22	Common Stock	M	2227	$6.16	Acquired	33671	Direct
2021-02-22	Common Stock	S	2227	$20.01	Disposed	31444	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2021-02-22	Stock Option (right to buy)	$3.51	M	1874	Disposed	2029-01-22	Common Stock (1874)	Direct
2021-02-22	Stock Option (right to buy)	$6.16	M	2227	Disposed	2030-01-14	Common Stock (2227)	Direct
2021-02-22	Stock Option (right to buy)	$3.51	M	1875	Disposed	2029-01-22	Common Stock (1875)	Direct
2021-02-22	Stock Option (right to buy)	$6.16	M	2227	Disposed	2030-01-14	Common Stock (2227)	Direct

Footnotes

F1: Transaction effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 12, 2020.

F2: This price is a weighted average price. These shares were sold in multiple transactions at prices ranging from $19.82 to $20.43, inclusive. The reporting person undertakes to provide to Mersana Therapeutics, Inc., any other 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 this footnote.

F3: The option vests in equal quarterly installments over the first four years after the vesting commencement date, January 23, 2019.

F4: The option vests in equal quarterly installments over the first four years after the vesting commencement date, January 15, 2020.