Castle Biosciences
CSTL
194 hedge funds and large institutions have $1.06B invested in Castle Biosciences in 2025 Q4 according to their latest regulatory filings, with 43 funds opening new positions, 64 increasing their positions, 68 reducing their positions, and 18 closing their positions.
139% more first-time investments, than exits
New positions opened: 43 | Existing positions closed: 18
100% more funds holding in top 10
Funds holding in top 10: 1 → 2 (+1)
75% more capital invested
Capital invested by funds: $608M → $1.06B (+$453M)
12% more funds holding
Funds holding: 173 → 194 (+21)
1.66% more ownership
Funds ownership: 91.87% → 93.52% (+1.7%)
6% less repeat investments, than reductions
Existing positions increased: 64 | Existing positions reduced: 68
Top Buyers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
RI
RTW Investments
New York
|
+$68.2M |
| 2 |
SPPAM
Summit Partners Public Asset Management
Boston,
Massachusetts
|
+$21.2M |
| 3 |
EAM
Eventide Asset Management
Boston,
Massachusetts
|
+$9.83M |
| 4 |
Wellington Management Group
Boston,
Massachusetts
|
+$7.05M |
| 5 |
PCM
Portolan Capital Management
Boston,
Massachusetts
|
+$6.91M |
Top Sellers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
B
Braidwell
Stamford,
Connecticut
|
-$20.8M |
| 2 |
Nuveen
Charlotte,
North Carolina
|
-$13.9M |
| 3 |
Dimensional Fund Advisors
Austin,
Texas
|
-$10.6M |
| 4 |
PHP
Parkman Healthcare Partners
Stamford,
Connecticut
|
-$10.5M |
| 5 |
Millennium Management
New York
|
-$8.58M |
CSTL Hedge Fund Activity: Q4 2025 in Review
194 of the 8,270 institutional investors tracked by Wall St. Rank reported a position in Castle Biosciences (CSTL) for Q4 2025, worth a combined $1.06B — up 75% from $608M a quarter earlier.
Buyers outnumbered sellers: 43 funds opened new CSTL positions and 18 closed out — a net gain of 25 holders — while 64 added to existing stakes and 68 trimmed.
The largest buyer was RTW Investments, opening a new position worth an estimated $68.2M. The largest seller was Braidwell, cutting an estimated $20.8M.
- 194 institutional investors held Castle Biosciences (CSTL) as of Q4 2025, up from 173 in Q3 2025.
- Funds reported $1.06B of Castle Biosciences stock for Q4 2025, up 75% quarter-over-quarter.
- 43 funds opened new Castle Biosciences positions in Q4 2025 and 18 closed out, a net change of +25 holders.
- The largest Castle Biosciences buyer in Q4 2025 was RTW Investments, an estimated $68.2M added.
- The largest Castle Biosciences seller in Q4 2025 was Braidwell, an estimated $20.8M sold.
Based on aggregated 13F filings for Q4 2025.