Mersana Therapeutics Ownership | Who Owns Mersana Therapeutics?

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Mersana Therapeutics Ownership Summary

Mersana Therapeutics is owned by 6.61% institutional investors, 1.47% insiders, and 91.92% retail investors. Nextech invest is the largest institutional shareholder, holding 9.83% of MRSN shares. Vanguard US Total Market Shares ETF is the top mutual fund, with 2.78% of its assets in Mersana Therapeutics shares.

MRSN Ownership Benchmark

Type	Name	% Inst	% Insiders	% Retail
Stock	Mersana Therapeutics	6.61%	1.47%	91.92%
Sector	Healthcare Stocks	35.49%	11.78%	52.72%
Industry	Biotech Stocks	34.84%	11.71%	53.45%

Institutional Shareholders

Top Institutional Shareholders by Total Shares

Holder	Shares	% Holding	Value
Nextech invest	12.07M	9.83%	$17.26M
Blackrock	8.38M	6.90%	$16.85M
Vanguard group	210.30K	4.22%	$6.08M
Groupe la francaise	61.49K	1.23%	$1.78M
Luminus management	50.00K	1.00%	$388.00K
Goldman sachs group	802.37K	0.65%	$1.15M
D. e. shaw	544.46K	0.44%	$778.58K
Clarivest asset management	500.50K	0.41%	$1.01M
Jacobs levy equity management	485.59K	0.40%	$976.04K
Bridgeway capital management	475.50K	0.39%	$955.75K

Top Institutional Shareholders by % of Total Assets

Holder	Shares	% Assets	Value
Nextech invest	12.07M	2.80%	$17.26M
Luminus management	50.00K	0.35%	$388.00K
Clarivest asset management	500.50K	0.10%	$1.01M
Groupe la francaise	61.49K	0.02%	$1.78M
Bridgeway capital management	475.50K	0.02%	$955.75K
Jacobs levy equity management	485.59K	0.00%	$976.04K
Prio wealth limited partnership	23.53K	0.00%	$47.29K
D. e. shaw	544.46K	0.00%	$778.58K
Blackrock	8.38M	0.00%	$16.85M
Public employees retirement system of ohio	20.59K	0.00%	$41.38K

Top Buyers

Holder	Shares	% Assets	Change
Blackrock	8.38M	0.00%	288.18K
Bridgeway capital management	475.50K	0.02%	243.20K
Nuveen asset management	232.22K	0.00%	81.02K
Groupe la francaise	61.49K	0.02%	61.49K
Clarivest asset management	500.50K	0.10%	28.65K

Top Sellers

Holder	Shares	% Assets	Change
Ecor1 capital	-	-	-11.33M
Schonfeld strategic advisors	-	-	-5.67M
Novo	-	-	-4.25M
Vr adviser	-	-	-3.57M
Cormorant asset management, lp	-	-	-2.60M

New Positions

Holder	Shares	% Assets	Change	Value
Groupe la francaise	61.49K	0.02%	61.49K	$1.78M
Wolverine trading	10.87K	-	10.87K	$15.43K

Sold Out

Holder	Change
Danske bank	-1.00
Farther finance advisors	-1.00
Frazier financial advisors	-5.00
Fmr	-8.00
Capital performance advisors llp	-11.00

Institutional Ownership Trends

Date	Holdings	Change %	Shares	Change %	Ownership	Change %	Increased Position	Change %	Decreased Position	Change %
Dec 31, 2025	10	-79.17%	329,630	-89.63%	6	0.16%	5	-37.50%	4	-90.00%
Sep 30, 2025	4	-94.81%	52,898	-99.92%	1	0.03%	-	-100.00%	4	-86.21%
Jun 30, 2025	81	-27.03%	77,176,495	-12.25%	61	1.22%	35	-36.36%	30	-3.23%
Mar 31, 2025	7	-94.85%	17,769,330	-82.96%	14	0.20%	3	-95.16%	1	-97.50%
Dec 31, 2024	130	7.44%	101,397,402	-12.65%	82	0.92%	58	13.73%	39	21.88%

Top Mutual Funds Shareholders

Holder	Shares	% Holding	Change
Vanguard US Total Market Shares ETF	3.47M	2.78%	-
Vanguard Total Stock Mkt Idx Inv	135.87K	2.72%	-2.97K
Vanguard Explorer Inv	2.01M	1.61%	-
Fidelity Small Cap Index	1.11M	0.89%	-
Vanguard Institutional Extnd Mkt Idx Tr	41.90K	0.84%	-19.09K
State St Russell Sm/Mid Cp® Indx NL Cl C	839.38K	0.67%	-
State St Russell Sm/Mid Cp® Indx SL Cl I	839.38K	0.67%	-
iShares Biotechnology ETF	23.92K	0.48%	-
iShares Russell 2000 ETF	569.31K	0.46%	-
Vanguard Russell 2000 ETF	564.71K	0.45%	4.82K

Recent Insider Transactions

Date	Name	Role	Activity	Value
Oct 27, 2025	Bala Mohan	SVP, Chief Development Officer	Sell	$762.30
Sep 12, 2025	Huber Martin H. Jr.	President, CEO	Sell	$14.71K
Jan 16, 2025	Mandelia Ashish	VP, Chief Accounting Officer	Sell	$2.06K
Jan 16, 2025	Protopapas Anna	-	Sell	$5.01K
Jan 16, 2025	Lowinger Timothy B	SVP, Chief Sci.&Tech. Officer	Sell	$4.67K

Insider Transactions Trends

Date	Buy	Sell
2026 Q1	-	-
2025 Q4	-	1
2025 Q3	-	1
2025 Q2	-	-
2025 Q1	-	18

MRSN Ownership FAQ

Who Owns Mersana Therapeutics?

Mersana Therapeutics shareholders are primarily institutional investors at 6.61%, followed by 1.47% insiders and 91.92% retail investors. The average institutional ownership in Mersana Therapeutics's industry, Biotech Stocks , is 34.84%, which Mersana Therapeutics falls below.

Who owns the most shares of Mersana Therapeutics?

Mersana Therapeutics’s largest shareholders are Nextech invest (12.07M shares, 9.83%), Blackrock (8.38M shares, 6.90%), and Vanguard group (210.3K shares, 4.22%). Together, they hold 20.95% of Mersana Therapeutics’s total shares outstanding.

Does Blackrock own Mersana Therapeutics?

Yes, BlackRock owns 6.90% of Mersana Therapeutics, totaling 8.38M shares as of Jun 2024. This represents 0.00% of BlackRock's total assets, with a market value of 16.85M$. In the last quarter, BlackRock increased its holdings by 288.18K shares, a 3.56% change.

Who is Mersana Therapeutics’s biggest shareholder by percentage of total assets invested?

Nextech invest is Mersana Therapeutics’s biggest shareholder by percentage of total assets invested, with 2.80% of its assets in 12.07M Mersana Therapeutics shares, valued at 17.26M$.

Who is the top mutual fund holder of Mersana Therapeutics shares?

Vanguard US Total Market Shares ETF is the top mutual fund holder of Mersana Therapeutics shares, with 2.78% of its total shares outstanding invested in 3.47M Mersana Therapeutics shares.

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