Sionna Therapeutics
SION
78 hedge funds and large institutions have $1.26B invested in Sionna Therapeutics in 2025 Q3 according to their latest regulatory filings, with 19 funds opening new positions, 20 increasing their positions, 19 reducing their positions, and 6 closing their positions.
217% more first-time investments, than exits
New positions opened: 19 | Existing positions closed: 6
20% more funds holding
Funds holding: 65 → 78 (+13)
5% more repeat investments, than reductions
Existing positions increased: 20 | Existing positions reduced: 19
0% more funds holding in top 10
Funds holding in top 10: 4 → 4 (0)
1.41% less ownership
Funds ownership: 98.47% → 97.06% (-1.4%)
26% less capital inflows, than outflows
Capital inflows: $35M | Capital outflows: $47M
Top Buyers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
Vanguard Group
Malvern,
Pennsylvania
|
+$11.2M |
| 2 |
Jennison Associates
New York
|
+$5.32M |
| 3 |
BlackRock
New York
|
+$4.51M |
| 4 |
Millennium Management
New York
|
+$4.35M |
| 5 |
State Street
Boston,
Massachusetts
|
+$2.52M |
Top Sellers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
Braidwell
Stamford,
Connecticut
|
-$16.7M |
| 2 |
Franklin Resources
San Mateo,
California
|
-$5.61M |
| 3 |
JP Morgan Chase
New York
|
-$5.28M |
| 4 |
T. Rowe Price Associates
Baltimore,
Maryland
|
-$4.86M |
| 5 |
Prudential Financial
Newark,
New Jersey
|
-$2.35M |
SION Hedge Fund Activity: Q3 2025 in Review
78 of the 7,653 institutional investors tracked by Wall St. Rank reported a position in Sionna Therapeutics (SION) for Q3 2025, worth a combined $1.26B — up 67% from $754M a quarter earlier.
Buyers outnumbered sellers: 19 funds opened new SION positions and 6 closed out — a net gain of 13 holders — while 20 added to existing stakes and 19 trimmed.
The largest buyer was Vanguard Group, adding an estimated $11.2M. The largest seller was Braidwell, cutting an estimated $16.7M.
- 78 institutional investors held Sionna Therapeutics (SION) as of Q3 2025, up from 65 in Q2 2025.
- Funds reported $1.26B of Sionna Therapeutics stock for Q3 2025, up 67% quarter-over-quarter.
- 19 funds opened new Sionna Therapeutics positions in Q3 2025 and 6 closed out, a net change of +13 holders.
- The largest Sionna Therapeutics buyer in Q3 2025 was Vanguard Group, an estimated $11.2M added.
- The largest Sionna Therapeutics seller in Q3 2025 was Braidwell, an estimated $16.7M sold.
Based on aggregated 13F filings for Q3 2025.