Mersana Therapeutics, Inc. — Director's Dealing 2021

Jan 21, 2021

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Mersana Therapeutics, Inc. (MRSN)
CIK: 0001442836
Period of Report: 2021-01-15

Reporting Person: Protopapas Anna (Director, President & CEO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2021-01-15	Common Stock	M	17709	—	Acquired	230120	Direct
2021-01-15	Common Stock	F	5198	$21.09	Disposed	224922	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2021-01-15	Restricted Stock Units	$	M	17709	Disposed		Common Stock (17709)	Direct
2021-01-15	Stock Option (right to buy)	$21.09	A	382500	Acquired	2031-01-15	Common Stock (382500)	Direct
2021-01-15	Restricted Stock Units	$	A	85000	Acquired		Common Stock (85000)	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 of common stock that have been withheld by the Issuer to satisfy its income tax withholding and remittance obligations in connection with the net settlement of the RSUs and does not represent a sale by the reporting person.

F3: 25% of the total number of RSUs vested on January 15, 2021, and thereafter shall vest in equal annual installments over the next three years.

F4: The option vests in equal quarterly installments over the first four years after the vesting commencement date, January 15, 2021.

F5: The restricted stock units vest in equal annual installments over the first four years after the vesting commencement date, January 15, 2021.