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 Q2 2025?

80 institutional investors reported MRSN - Mersana Therapeutics, Inc. - Common Stock, par value $0.0001 per share for Q2 2025. Use the holders table for investor-level position and value details.

CUSIP: 59045L106

Q2 2025 13F Holders as of 30 Jun 2025

Security type / class: Equity / Common Stock, par value $0.0001 per share
Total 13F shares: 77,200,692
Total 13F value: $22,849,022
Share change: -10,550,209
Put/Call ratio: 41%
SEC-reported price per share: $0.30
Number of holders: 80
Value change: -$3,437,337
Number of buys: 35
Number of sells: 70
Shares outstanding: 4,992,318

Security key

59045L106

Report period

Q2 2025

Institutions

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

Nextech Crossover I GP S....

Disclosed value leader

Nextech Crossover I GP S....

Comparable rows

15/15

Latest evidence

31 Mar 2025

13D/G 13F Lead comparable stake: 10% 13D/G row: Nextech Crossover I GP S.a r.l. Showing 1-6 of 15 holder rows.

Quick read

Nextech Crossover I GP S.a r.l. leads the comparable SEC ownership view at 10%.

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 Nextech Crossover I GP S.a r.l.'s linked filing trail.

Comparable ownership Top 5

Nextech Crossover I GP S.a r.l. 10%

VANGUARD GROUP INC 6.7%

BlackRock, Inc. 3%

Venrock Healthcare Capital Partne... 2.9%

Nextech Invest, Ltd. 242%

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
Nextech Crossover I GP S.a r.l.	13D/G 13D/G	10%	$4,344,209 12,067,246 shares	$0	20 Dec 2024
VANGUARD GROUP INC	13D/G 13F The Vanguard Group · Company 13D/G 13F	6.7%	$3,015,996 8,377,767 shares	$0	31 Mar 2025
BlackRock, Inc.	13F 13D/G Company 13F 13D/G	3% from 13D/G	$2,865,872 8,326,182 shares	—	31 Mar 2025
Venrock Healthcare Capital Partners III, L.P.	13D/G 13D/G	2.9%	$1,286,757 3,574,325 shares	-$2,406,047	31 Mar 2025
Nextech Invest, Ltd.	13F Company 13F	242%	$4,153,546 12,067,246 shares	—	31 Mar 2025
Bain Capital Life Sciences Investors, LLC	13F Company 13F	174%	$2,982,036 8,663,673 shares	—	31 Mar 2025

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 Q2 2025

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

Institutions

77,200,692

Rows available

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 Q2 2025 vs Q4 2025 Across Filers

Q4 2025 holders

Q2 2025 holders

Holder diff

Investor	Q4 2025 Shares	Q2 2025 Shares	Share Diff	Share Chg %	Q4 2025 value	Q2 2025 value	Value change	Value Chg %

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

Quarterly Holders Trend

Quarterly Value Trend

Quarterly Shares Trend