MBX Biosciences
118 hedge funds and large institutions have $836M invested in MBX Biosciences in 2025 Q3 according to their latest regulatory filings, with 39 funds opening new positions, 29 increasing their positions, 30 reducing their positions, and 9 closing their positions.
333% more first-time investments, than exits
New positions opened: 39 | Existing positions closed: 9
99% more capital invested
Capital invested by funds: $420M → $836M (+$416M)
34% more funds holding
Funds holding: 88 → 118 (+30)
32.04% more ownership
Funds ownership: 110.22% → 142.26% (+32%)
0% more funds holding in top 10
Funds holding in top 10: 3 → 3 (0)
3% less repeat investments, than reductions
Existing positions increased: 29 | Existing positions reduced: 30
47% less call options, than puts
Call options by funds: $15.3M | Put options by funds: $29M
Top Buyers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
Wellington Management Group
Boston,
Massachusetts
|
+$34.2M |
| 2 |
KCM
Kynam Capital Management
Princeton,
New Jersey
|
+$26.7M |
| 3 |
Citadel Advisors
Miami,
Florida
|
+$13.3M |
| 4 |
EC
EcoR1 Capital
San Francisco,
California
|
+$13M |
| 5 |
DTC
Deep Track Capital
Greenwich,
Connecticut
|
+$12.9M |
Top Sellers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
MB
MPM BioImpact
Boston,
Massachusetts
|
-$14.8M |
| 2 |
T. Rowe Price Associates
Baltimore,
Maryland
|
-$5.24M |
| 3 |
SSA
Schonfeld Strategic Advisors
New York
|
-$4.66M |
| 4 |
Point72 Asset Management
Stamford,
Connecticut
|
-$4.63M |
| 5 |
RCM
RA Capital Management
Boston,
Massachusetts
|
-$4.31M |
MBX Hedge Fund Activity: Q3 2025 in Review
118 of the 7,620 institutional investors tracked by Wall St. Rank reported a position in MBX Biosciences (MBX) for Q3 2025, worth a combined $836M — up 99% from $420M a quarter earlier.
Buyers outnumbered sellers: 39 funds opened new MBX positions and 9 closed out — a net gain of 30 holders — while 29 added to existing stakes and 30 trimmed.
The largest buyer was Wellington Management Group, adding an estimated $34.2M. The largest seller was MPM BioImpact, exiting entirely with an estimated $14.8M sold.
- 118 institutional investors held MBX Biosciences (MBX) as of Q3 2025, up from 88 in Q2 2025.
- Funds reported $836M of MBX Biosciences stock for Q3 2025, up 99% quarter-over-quarter.
- 39 funds opened new MBX Biosciences positions in Q3 2025 and 9 closed out, a net change of +30 holders.
- The largest MBX Biosciences buyer in Q3 2025 was Wellington Management Group, an estimated $34.2M added.
- The largest MBX Biosciences seller in Q3 2025 was MPM BioImpact, an estimated $14.8M sold.
Based on aggregated 13F filings for Q3 2025.