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 Q4 2020?

147 institutional investors reported MRSN - Mersana Therapeutics, Inc. - Common Stock, par value $0.0001 per share for Q4 2020. Use the holders table for investor-level position and value details.

CUSIP: 59045L106

Q4 2020 13F Holders as of 31 Dec 2020

Security type / class: Equity / Common Stock, par value $0.0001 per share
Total 13F shares: 68,137,745
Total 13F value: $1,813,136,515
Share change: -265,069
Put/Call ratio: 39%
SEC-reported price per share: $26.61
Number of holders: 147
Value change: +$51,864,511
Number of buys: 81
Number of sells: 59
Shares outstanding: 4,992,318

Security key

59045L106

Report period

Q4 2020

Institutions

147

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

BlackRock Finance, Inc.

Disclosed value leader

BlackRock Finance, Inc.

Comparable rows

15/15

Latest evidence

30 Sep 2020

13F Lead comparable stake: 145% Showing 1-6 of 15 holder rows.

Quick read

BlackRock Finance, Inc. leads the comparable SEC ownership view at 145%.

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 BlackRock Finance, Inc.'s linked filing trail.

Comparable ownership Top 5

BlackRock Finance, Inc. 145%

Avoro Capital Advisors LLC 136%

NEA Management Company, LLC 119%

WELLINGTON MANAGEMENT GROUP LLP 76%

Consonance Capital Management LP 69%

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
BlackRock Finance, Inc.	13F Company 13F	145%	$135,031,000 7,252,006 shares	—	30 Sep 2020
Avoro Capital Advisors LLC	13F Company 13F	136%	$126,616,000 6,800,000 shares	—	30 Sep 2020
NEA Management Company, LLC	13F Company 13F	119%	$110,966,000 5,959,520 shares	—	30 Sep 2020
WELLINGTON MANAGEMENT GROUP LLP	13F Company 13F	76%	$70,585,000 3,790,832 shares	—	30 Sep 2020
Consonance Capital Management LP	13F Company 13F	69%	$64,577,000 3,468,171 shares	—	30 Sep 2020
Bain Capital Life Sciences Investors, LLC	13F Company 13F	69%	$64,158,000 3,445,667 shares	—	30 Sep 2020

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 Q4 2020

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

Institutions

147

68,137,745

Rows available

147

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 Q4 2020 vs Q4 2025 Across Filers

Q4 2025 holders

Q4 2020 holders

147

Holder diff

144

Investor	Q4 2025 Shares	Q4 2020 Shares	Share Diff	Share Chg %	Q4 2025 value	Q4 2020 value	Value change	Value Chg %

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

Quarterly Holders Trend

Quarterly Value Trend

Quarterly Shares Trend