13F Insight
DOSSIER · 13F Holders · Q1 2026Healthcare · Services-Medical LaboratoriesHigh-convictionMulti-bagger
CSTL

CASTLE BIOSCIENCES INC

194 institutions still hold CASTLE BIOSCIENCES INC as of Q1 2026. Tracked across SEC 13F-HR filings, with insider and 13D/G activity surfaced alongside.

CUSIP 14843C105·Services-Medical Laboratories·194 13F holders·last filed Mar 31, 2026
Market cap
—
▲ 3.2%
vs prior quarter
13F value held
$521M
49.0% inst. owned
of float
Holders
194
-18 QoQ
filers reporting
Activity
+8 / −91
+962 added · −802 reduced
this quarter
Concentration
14.05%
BlackRock, Inc. #1
top holder share
AI Holders Summary · Q1 2026

194 institutions reported CSTL in Q1 2026. BlackRock, Inc. leads at 14.0% of the visible book. -18 net institutions QoQ — distribution reading.

Top holders

Sorted by position value. Source: SEC EDGAR 13F-HR filings.

#HolderValueShares% port.Quarter
01
BlackRock, Inc.
CIK 0002012383
$73M3.0M0.00%Q1 202602
RTW INVESTMENTS, LP
CIK 0001493215
$68M2.8M0.67%Q1 202603
Portolan Capital Management, LLC
CIK 0001350290
$67M1.7M3.60%Q4 202504
PRINCIPAL FINANCIAL GROUP INC
CIK 0001126328
$43M1.8M0.02%Q1 202605
VANGUARD CAPITAL MANAGEMENT LLC
CIK 0002100119· Index
$29M1.2M0.00%Q1 202606
DIMENSIONAL FUND ADVISORS LP
CIK 0000354204· Quasi-passive
$26M1.0M0.01%Q1 202607
SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC
CIK 0001638555
$23M941K0.62%Q1 202608
Vanguard Portfolio Management
CIK 0002100121· Index
$21M862K0.00%Q1 202609
Allianz Asset Management GmbH
CIK 0001535323
$20M811K0.02%Q1 202610
STATE STREET CORP
CIK 0000093751
$19M769K0.00%Q1 202611
GEODE CAPITAL MANAGEMENT, LLC
CIK 0001214717· Index
$18M728K0.00%Q1 202612
CITADEL ADVISORS LLC
CIK 0001423053
$16M407K0.00%Q4 202513
AIGH Capital Management LLC
CIK 0001835943
$14M591K1.98%Q1 202614
Qube Research & Technologies Ltd
CIK 0001729829
$14M560K0.02%Q1 202615
PALISADE CAPITAL MANAGEMENT, LP
CIK 0001009006
$13M536K0.44%Q1 202616
RENAISSANCE TECHNOLOGIES LLC
CIK 0001037389
$13M533K0.02%Q1 202617
Nuveen, LLC
CIK 0001871926
$13M522K0.00%Q1 202618
WASATCH ADVISORS LP
CIK 0000814133
$11M455K0.07%Q1 202619
MORGAN STANLEY
CIK 0000895421
$11M429K0.00%Q1 202620
EVENTIDE ASSET MANAGEMENT, LLC
CIK 0001442891
$9M386K0.16%Q1 2026
Page 1 of 10
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