Mersana Therapeutics
MRSN
MRSN was delisted on the 5th of January, 2026.
109 hedge funds and large institutions have $648M invested in Mersana Therapeutics in 2021 Q3 according to their latest regulatory filings, with 11 funds opening new positions, 45 increasing their positions, 34 reducing their positions, and 32 closing their positions.
32% more repeat investments, than reductions
Existing positions increased: 45 | Existing positions reduced: 34
0.23% less ownership
Funds ownership: 4.06% → 3.83% (-0.23%)
17% less funds holding
Funds holding: 131 → 109 (-22)
22% less call options, than puts
Call options by funds: $1.22M | Put options by funds: $1.57M
32% less capital invested
Capital invested by funds: $958M → $648M (-$310M)
33% less funds holding in top 10
Funds holding in top 10: 3 → 2 (-1)
66% less first-time investments, than exits
New positions opened: 11 | Existing positions closed: 32
Top Buyers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
BG
Bellevue Group
Kuesnacht,
Switzerland
|
+$15.4M |
| 2 |
State Street
Boston,
Massachusetts
|
+$9.86M |
| 3 |
Goldman Sachs
New York
|
+$6.64M |
| 4 |
Morgan Stanley
New York
|
+$6.33M |
| 5 |
Vanguard Group
Malvern,
Pennsylvania
|
+$5.84M |
Top Sellers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
Westfield Capital Management
Boston,
Massachusetts
|
-$28.6M |
| 2 |
T. Rowe Price Associates
Baltimore,
Maryland
|
-$15.6M |
| 3 |
Wellington Management Group
Boston,
Massachusetts
|
-$10.2M |
| 4 |
Citadel Advisors
Miami,
Florida
|
-$6.34M |
| 5 |
GTC
Ghost Tree Capital
New York
|
-$6.11M |
MRSN Hedge Fund Activity: Q3 2021 in Review
109 of the 5,728 institutional investors tracked by Wall St. Rank reported a position in Mersana Therapeutics (MRSN) for Q3 2021, worth a combined $648M — down 32% from $958M a quarter earlier.
Sellers outnumbered buyers: 32 funds closed out of MRSN and 11 opened new positions — a net loss of 21 holders — while 34 trimmed existing stakes and 45 added.
The largest buyer was Bellevue Group, adding an estimated $15.4M. The largest seller was Westfield Capital Management, exiting entirely with an estimated $28.6M sold.
- 109 institutional investors held Mersana Therapeutics (MRSN) as of Q3 2021, down from 131 in Q2 2021.
- Funds reported $648M of Mersana Therapeutics stock for Q3 2021, down 32% quarter-over-quarter.
- 11 funds opened new Mersana Therapeutics positions in Q3 2021 and 32 closed out, a net change of -21 holders.
- The largest Mersana Therapeutics buyer in Q3 2021 was Bellevue Group, an estimated $15.4M added.
- The largest Mersana Therapeutics seller in Q3 2021 was Westfield Capital Management, an estimated $28.6M sold.
Based on aggregated 13F filings for Q3 2021.