Mersana Therapeutics, Inc. - Common Stock, par value $0.0001 per share (MRSN)

Q: What does CUSIP 59045L106 represent in this 13F holders report?

CUSIP 59045L106 is the security identifier for MRSN - Mersana Therapeutics, Inc. - Common Stock, par value $0.0001 per share used to aggregate holder disclosures.

Q: How many institutions held MRSN - Mersana Therapeutics, Inc. - Common Stock, par value $0.0001 per share in Q1 2023?

156 institutional investors reported MRSN - Mersana Therapeutics, Inc. - Common Stock, par value $0.0001 per share for Q1 2023. Use the holders table for investor-level position and value details.

CUSIP: 59045L106

Q1 2023 13F Holders as of 31 Mar 2023

Security type / class: Equity / Common Stock, par value $0.0001 per share
Total 13F shares: 106,632,085
Total 13F value: $437,242,303
Share change: +5,323,299
Put/Call ratio: 11%
SEC-reported price per share: $4.11
Number of holders: 156
Value change: +$17,660,953
Number of buys: 75
Number of sells: 64
Shares outstanding: 4,992,318

Security key

59045L106

Report period

Q1 2023

Institutions

156

Top holders

MRSN full security history Ownership snapshot Full 13F holder table Newer quarter: Q4 2025 Mersana Therapeutics, Inc. SEC filings Mersana Therapeutics, Inc. company facts

Broader feeds

Latest 13F filings Latest 13D/G filings Investors directory

Reporting periods

Holder history for CUSIP 59045L106

Newer quarter: Q4 2025

Recent filing periods:

Q1 2026 Q4 2025

Ownership snapshot

Top reported holders of MRSN - Mersana Therapeutics, Inc. - Common Stock, par value $0.0001 per share (13F + 13D/G + 3/4/5)

Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.

Comparable stake leader

ORBIMED ADVISORS LLC

Disclosed value leader

ORBIMED ADVISORS LLC

Comparable rows

15/15

Latest evidence

31 Dec 2022

13F Lead comparable stake: 181% Showing 1-6 of 15 holder rows.

Quick read

ORBIMED ADVISORS LLC leads the comparable SEC ownership view at 181%.

15 of 15 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.

Open SEC evidence Opens ORBIMED ADVISORS LLC's linked filing trail.

Comparable ownership Top 5

ORBIMED ADVISORS LLC 181%

Bain Capital Life Sciences Invest... 174%

Avoro Capital Advisors LLC 151%

BlackRock Finance, Inc. 150%

STATE STREET CORP 117%

Ownership % is shown only when SEC disclosures are safely comparable across share classes.

Detailed SEC evidence table Showing 1-6 of 15 holder rows

Holder	Evidence	Ownership %	Position	12M Net Δ	As of
ORBIMED ADVISORS LLC	13F Company 13F	181%	$52,807,021 9,011,437 shares	—	31 Dec 2022
Bain Capital Life Sciences Investors, LLC	13F Company 13F	174%	$50,769,000 8,663,673 shares	—	31 Dec 2022
Avoro Capital Advisors LLC	13F Company 13F	151%	$44,243,000 7,550,000 shares	—	31 Dec 2022
BlackRock Finance, Inc.	13F Company 13F	150%	$43,902,704 7,491,929 shares	—	31 Dec 2022
STATE STREET CORP	13F Company 13F	117%	$34,316,517 5,856,061 shares	—	31 Dec 2022
VANGUARD GROUP INC	13F Company 13F	89%	$26,071,374 4,449,040 shares	—	31 Dec 2022

How to read this table

Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.

13F holder rows

Institutional holders as of Q1 2023

Investor-level positions for this CUSIP, loaded as an interactive table.

Institutions

156

106,632,085

Rows available

156

Investor	Option	Weight %	Change %	SEC-reported value	* Price	Shares	Share Change	Activity	Report Period

^* SEC-reported price is the security price as of the portfolio date and can indicate the last known price at which the security was still held. The marker flags a reported price that did not pass the local price check.

Compare Q1 2023 vs Q4 2025 Across Filers

Q4 2025 holders

Q1 2023 holders

156

Holder diff

153

Investor	Q4 2025 Shares	Q1 2023 Shares	Share Diff	Share Chg %	Q4 2025 value	Q1 2023 value	Value change	Value Chg %

Trend: ostatnie 8 kwartałów (+ wybrane okresy porównania).

Quarterly Holders Trend

Quarterly Value Trend

Quarterly Shares Trend