Castle Biosciences
CSTL
177 hedge funds and large institutions have $654M invested in Castle Biosciences in 2026 Q2 according to their latest regulatory filings, with 24 funds opening new positions, 80 increasing their positions, 56 reducing their positions, and 30 closing their positions.
43% more repeat investments, than reductions
Existing positions increased: 80 | Existing positions reduced: 56
4% less capital invested
Capital invested by funds: $678M → $654M (-$23.9M)
2.49% less ownership
Funds ownership: 92.86% → 90.37% (-2.5%)
5% less funds holding
Funds holding: 186 → 177 (-9)
20% less first-time investments, than exits
New positions opened: 24 | Existing positions closed: 30
100% less funds holding in top 10
Funds holding in top 10: 1 → 0 (-1)
Top Buyers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
Mackenzie Financial
Toronto Ontario,
Ontario, Canada
|
+$16M |
| 2 |
JFG
Jefferies Financial Group
New York
|
+$14.4M |
| 3 |
Acadian Asset Management
Boston,
Massachusetts
|
+$9.67M |
| 4 |
Point72 Asset Management
Stamford,
Connecticut
|
+$7.96M |
| 5 |
KCM
Kennedy Capital Management
St Louis,
Missouri
|
+$7.76M |
Top Sellers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
PCM
Portolan Capital Management
Boston,
Massachusetts
|
-$22.8M |
| 2 |
EAM
Eventide Asset Management
Boston,
Massachusetts
|
-$9.49M |
| 3 |
Schroder Investment Management Group
London,
United Kingdom
|
-$7.04M |
| 4 |
PCM
Palisade Capital Management
Fort Lee,
New Jersey
|
-$6.77M |
| 5 |
Nuveen
Charlotte,
North Carolina
|
-$6.47M |
CSTL Hedge Fund Activity: Q2 2026 in Review
177 of the 8,318 institutional investors tracked by Wall St. Rank reported a position in Castle Biosciences (CSTL) for Q2 2026, worth a combined $654M — down 3.5% from $678M a quarter earlier.
Sellers outnumbered buyers: 30 funds closed out of CSTL and 24 opened new positions — a net loss of 6 holders — while 56 trimmed existing stakes and 80 added.
The largest buyer was Mackenzie Financial, adding an estimated $16M. The largest seller was Portolan Capital Management, cutting an estimated $22.8M.
- 177 institutional investors held Castle Biosciences (CSTL) as of Q2 2026, down from 186 in Q1 2026.
- Funds reported $654M of Castle Biosciences stock for Q2 2026, down 3.5% quarter-over-quarter.
- 24 funds opened new Castle Biosciences positions in Q2 2026 and 30 closed out, a net change of -6 holders.
- The largest Castle Biosciences buyer in Q2 2026 was Mackenzie Financial, an estimated $16M added.
- The largest Castle Biosciences seller in Q2 2026 was Portolan Capital Management, an estimated $22.8M sold.
Based on aggregated 13F filings for Q2 2026.