EC
MRSN

EcoR1 Capital’s Mersana Therapeutics MRSN Stock Holding History

EcoR1 Capital’s Portfolio MRSN Stock Details MRSN Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2025
Q1 		– Sell
-453,120
Closed -$16.2M – 58
2024
Q4 		$16.2M Sell
453,120
-321,468
-42% -$16.6M 0.61% 31
2024
Q3 		$36.6M Hold
774,588
– – 1.25% 20
2024
Q2 		$38.9M Hold
774,588
– – 1.19% 22
2024
Q1 		$86.8M Hold
774,588
– – 2.19% 16
2023
Q4 		$44.9M Hold
774,588
– – 1.17% 16
2023
Q3 		$24.6M Buy
+774,588
New +$36.8M 0.83% 24
2022
Q3 		– Sell
-12,438
Closed -$1.44M – 83
2022
Q2 		$1.44M Sell
12,438
-625
-5% -$58.8K 0.05% 66
2022
Q1 		$1.3M Buy
+13,063
New +$1.53M 0.04% 73
2019
Q3 		– Sell
-55,689
Closed -$5.64M – 42
2019
Q2 		$5.64M Sell
55,689
-36,311
-39% -$4.28M 0.57% 27
2019
Q1 		$12.1M Buy
+92,000
New +$11.6M 1.12% 25
2018
Q4 		– Sell
-19,825
Closed -$4.96M – 57
2018
Q3 		$4.96M Buy
+19,825
New +$6.64M 0.45% 36

Other funds holding MRSN

NI
Nextech Invest Zurich, Switzerland $2.11B AUM 413.84% 1-Year Est. Return
BCLSI
Bain Capital Life Sciences Investors Boston, Massachusetts $1.68B AUM 126.09% 1-Year Est. Return
Vanguard Group
Vanguard Group Malvern, Pennsylvania $6.9T AUM 27.45% 1-Year Est. Return
BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
SSA
Schonfeld Strategic Advisors New York $27.9B AUM 51.18% 1-Year Est. Return
AQR Capital Management
AQR Capital Management Greenwich, Connecticut $287B AUM 42.33% 1-Year Est. Return
RSCM
Rock Springs Capital Management Baltimore, Maryland $2.05B AUM 161.37% 1-Year Est. Return
VA
VR Adviser New York $3.3B AUM 525.74% 1-Year Est. Return
SCM
Silverarc Capital Management Boston, Massachusetts $962M AUM 524.64% 1-Year Est. Return
Acadian Asset Management
Acadian Asset Management Boston, Massachusetts $84.2B AUM 55.88% 1-Year Est. Return

EcoR1 Capital's MRSN Position: Q1 2025 in Review

EcoR1 Capital sold out of Mersana Therapeutics (MRSN) in Q1 2025, closing a stake of 453,120 shares — an estimated $16.2M sold.

EcoR1 Capital first reported a position in MRSN in Q3 2018 and held it in 11 quarters. The position peaked at $86.8M in Q1 2024. 108 funds tracked by Wall St. Rank hold MRSN as of Q1 2025.

  • EcoR1 Capital reported no remaining Mersana Therapeutics position as of Q1 2025 after selling out during the quarter.
  • EcoR1 Capital sold 453,120 Mersana Therapeutics shares in Q1 2025, an estimated $16.2M.
  • EcoR1 Capital first reported a position in Mersana Therapeutics in Q3 2018 and held it in 11 quarters.
  • EcoR1 Capital's Mersana Therapeutics position peaked at $86.8M in Q1 2024.
  • 108 funds tracked by Wall St. Rank held Mersana Therapeutics as of Q1 2025.

Based on EcoR1 Capital's 13F filing for Q1 2025, filed 15 May 2025.