Castle Biosciences, Inc. (CSTL)

Highly Crowded

Held by 180 of 5,944 reporting institutions (91th percentile) — extremely crowded.

Data as of Q1 2026

Institutional Ownership

90.78%

QoQ Change

-1.81%

Total Value

$653.2B

Shares Outstanding

30.3M

Crowding AnalysisHighly Crowded

Holders180of 5,944

Avg: 68

Uncrowded91th percentileCrowded

Institutional Activity

Buy/Sell Ratio1.02x

78th percentile

101 buying99 selling

+29

New

-38

Closed

+308K

Net shares

Holding Period Distribution

estimate

Median: 3 QAvg: 3.2 QHolders: 180

Ownership Concentration

Top 5: 36.5%Top 10: 52.5%

BlackRock,10.8%

RTW INVESTMENTS,10.0%

PRINCIPAL FINANCIAL GROUP6.4%

Portolan Capital Management,4.9%

VANGUARD CAPITAL MANAGEMENT4.3%

Others (175)63.5%

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Conviction-Weighted Ownership

Median weight: 0.01%Avg weight: 0.31%Max: 1.76%High conviction (>1%): 1

BlackRock,

RTW INVESTMENTS,

PRINCIPAL FINANCIAL GROUP

Portolan Capital Management,

VANGUARD CAPITAL MANAGEMENT

DIMENSIONAL FUND ADVISORS

SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT,

VANGUARD PORTFOLIO MANAGEMENT

Allianz Asset Management GmbH

STATE STREET

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Whale Moves Timeline (8 Quarters)

Biggest dollar-value position changes among top 10 holders

NEWVANGUARD CAPITAL MANAGEMENT$29M1.2M shr

NEWVANGUARD PORTFOLIO MANAGEMENT$21M862K shr

NEWAllianz Asset Management GmbH$20M811K shr

BOUGHTRTW INVESTMENTS$16M643K shr

SOLDPortolan Capital Management$9M379K shr

NEWRTW INVESTMENTS$82M2.1M shr

NEWSUMMIT PARTNERS PUBLIC ASSET MANAGEMENT$41M1.1M shr

SOLDDIMENSIONAL FUND ADVISORS$13M330K shr

BOUGHTPortolan Capital Management$8M214K shr

SOLDBlackRock$3M85K shr

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Institutional Trends (8 Quarters)

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Institutional Holders

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