UOC
MRSN

UBS O'Connor’s Mersana Therapeutics MRSN Stock Holding History

UBS O'Connor’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
Q2 		– Sell
-3,909
Closed -$33.6K – 435
2025
Q1 		$33.6K Sell
3,909
-12,492
-76% -$193K ﹤0.01% 292
2024
Q4 		$586K Sell
16,401
-6,400
-28% -$331K 0.01% 267
2024
Q3 		$1.08M Buy
22,801
+1,029
+5% +$45.4K 0.03% 270
2024
Q2 		$1.09M Buy
21,772
+4,400
+25% +$318K 0.03% 283
2024
Q1 		$1.95M Sell
17,372
-4,854
-22% -$483K 0.06% 178
2023
Q4 		$1.29M Buy
22,226
+10,369
+87% +$417K 0.04% 240
2023
Q3 		$376K Buy
+11,857
New +$564K 0.01% 422
2023
Q2 		– Sell
-18,508
Closed -$2.71M – 619
2023
Q1 		$1.9M Sell
18,508
-808
-4% -$113K 0.05% 326
2022
Q4 		$2.83M Buy
19,316
+4,256
+28% +$719K 0.05% 328
2022
Q3 		$2.54M Sell
15,060
-4,582
-23% -$745K 0.03% 490
2022
Q2 		$2.27M Buy
19,642
+10,682
+119% +$1M 0.02% 622
2022
Q1 		$894K Buy
+8,960
New +$1.05M 0.01% 714

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
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
BlackRock
BlackRock New York $6.73T AUM 46.02% 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
Renaissance Technologies
Renaissance Technologies New York $72.6B AUM 54.88% 1-Year Est. Return

UBS O'Connor's MRSN Position: Q2 2025 in Review

UBS O'Connor sold out of Mersana Therapeutics (MRSN) in Q2 2025, closing a stake of 3,909 shares — an estimated $33.6K sold.

UBS O'Connor first reported a position in MRSN in Q1 2022 and held it in 12 quarters. The position peaked at $2.83M in Q4 2022. 83 funds tracked by Wall St. Rank hold MRSN as of Q2 2025.

  • UBS O'Connor reported no remaining Mersana Therapeutics position as of Q2 2025 after selling out during the quarter.
  • UBS O'Connor sold 3,909 Mersana Therapeutics shares in Q2 2025, an estimated $33.6K.
  • UBS O'Connor first reported a position in Mersana Therapeutics in Q1 2022 and held it in 12 quarters.
  • UBS O'Connor's Mersana Therapeutics position peaked at $2.83M in Q4 2022.
  • 83 funds tracked by Wall St. Rank held Mersana Therapeutics as of Q2 2025.

Based on UBS O'Connor's 13F filing for Q2 2025, filed 14 Aug 2025.