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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.

New
Increased
Maintained
Reduced
Closed

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

Holders
194
Holders Change
+21
Holders Change %
+12.14%
% of All Funds
2.36%
Holding in Top 10
2
Holding in Top 10 Change
+1
Holding in Top 10 Change %
+100%
% of All Funds
0.02%
New
43
Increased
64
Reduced
68
Closed
18
Calls
$3.25M
Puts
–
Net Calls
+$3.25M
Net Calls Change
+$2.48M

Top Buyers

1
RI
RTW Investments
New York
+$68.2M
2
SPPAM
Summit Partners Public Asset Management
Massachusetts
+$21.2M
3
EAM
Eventide Asset Management
Massachusetts
+$9.83M
4
Wellington Management Group
Wellington Management Group
Massachusetts
+$7.05M
5
PCM
Portolan Capital Management
Massachusetts
+$6.91M

Top Sellers

1
B
Braidwell
Connecticut
-$20.8M
2
N
Nuveen
North Carolina
-$13.9M
3
Dimensional Fund Advisors
Dimensional Fund Advisors
Texas
-$10.6M
4
PHP
Parkman Healthcare Partners
Connecticut
-$10.5M
5
Millennium Management
Millennium Management
New York
-$8.58M
Name Holding Trade Value Shares
Change 		Change in
Stake
BlackRock
1
BlackRock
New York
$121M -$2.73M -84,650 -3%
Vanguard Group
2
Vanguard Group
Pennsylvania
$85.6M +$887K +27,511 +1%
RI
3
RTW Investments
New York
$82.3M +$68.2M +2,115,237 New
Principal Financial Group
4
Principal Financial Group
Iowa
$70.3M +$428K +13,289 +0.7%
PCM
5
Portolan Capital Management
Massachusetts
$67.3M +$6.91M +214,352 +14%
Dimensional Fund Advisors
6
Dimensional Fund Advisors
Texas
$44.5M -$10.6M -330,290 -22%
SPPAM
7
Summit Partners Public Asset Management
Massachusetts
$41.2M +$21.2M +658,725 +165%
State Street
8
State Street
Massachusetts
$28.6M +$399K +12,374 +2%
Geode Capital Management
9
Geode Capital Management
Massachusetts
$27.8M +$526K +16,303 +2%
ACM
10
AIGH Capital Management
Maryland
$24.3M -$2.66M -82,568 -12%
Allianz Asset Management
11
Allianz Asset Management
Germany
$24.2M -$840K -26,052 -4%
PCM
12
Palisade Capital Management
New Jersey
$22.1M -$2.29M -70,879 -11%
WA
13
Wasatch Advisors
Utah
$20.9M -$4.25M -131,879 -20%
N
14
Nuveen
North Carolina
$20.4M -$13.9M -432,400 -45%
Schroder Investment Management Group
15
Schroder Investment Management Group
United Kingdom
$19.3M -$89.9K -2,789 -0.6%
Renaissance Technologies
16
Renaissance Technologies
New York
$19.2M -$2.24M -69,500 -12%
Acadian Asset Management
17
Acadian Asset Management
Massachusetts
$15.2M -$1.97M -61,246 -14%
Connor, Clark & Lunn Investment Management (CC&L)
18
Connor, Clark & Lunn Investment Management (CC&L)
British Columbia, Canada
$15.1M +$1.7M +52,600 +16%
Citadel Advisors
19
Citadel Advisors
Florida
$14.3M +$3.72M +115,441 +46%
Millennium Management
20
Millennium Management
New York
$12M -$8.58M -266,175 -46%
EAM
21
Eventide Asset Management
Massachusetts
$11.9M +$9.83M +305,000 New
Goldman Sachs
22
Goldman Sachs
New York
$11.2M -$1.87M -57,864 -17%
KCM
23
Kornitzer Capital Management
Kansas
$10.4M -$341K -10,581 -4%
Bank of America
24
Bank of America
North Carolina
$10.2M -$1.69M -52,351 -17%
Northern Trust
25
Northern Trust
Illinois
$10.2M -$646K -20,024 -7%
1
2 3 4 5

CSTL Hedge Fund Activity: Q4 2025 in Review

194 of the 8,223 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.