Castle Biosciences, Inc.· CSTL

🇺🇸 US · SmallBroad USNASDAQ

HealthcareMedical - Diagnostics & ResearchWebsite

Price: $31.18
Day: +2.60%
Mkt Cap: $952.53M
52W Range: $17.72 – $44.28
Volume: 621.0K
Beta: 1.00

D55D FrameworkQuarterly Data

Holdings Analysis

Insider activity, institutional flows, and fund ownership.

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stockoscope.com

Castle Biosciences, Inc.

CSTL|Healthcare|Medical - Diagnostics & Research

Current price: $31

Smart Money

Dimension 5 of 5

Insider Activity, Q3 2026

Latest scored quarter, net flow, and top transactions by value

Net dollar flow-$722.3K

Net share flow-29.9K

Purchases0 ($0)

Sales18 ($722.3K)

Top Notable Transactions

Insider

Type

Value

Date

MAETZOLD DEREK J

Sale

$839.0K

Aug 13

MAETZOLD DEREK J

Sale

$717.3K

Dec 15

Oelschlager Kristen M

Sale

$664.5K

Nov 11

Institutional Ownership, Q1 2026

Ownership share, position changes, share flow, and top holders

Ownership92.4%

13F share flow-56.7%

Investors holding190

+129 adding-99 reducing

101

New 28Inc 101Red 61Closed 38

Top Institutional Holders

Institution

Value

Change

BLACKROCK, INC.

$73.2M

-18.0%

RTW INVESTMENTS, LP

$67.7M

+11.4%

PRINCIPAL FINANCIAL GROUP INC

$43.5M

-16.4%

PORTOLAN CAPITAL MANAGEMENT, LLC

$33.1M

-33.3%

ETF & Mutual Fund Activity, Q2 2026

Latest meaningful quarter: fund-by-fund buying / unchanged / selling

Funds reporting100

Total shares held6.8M

Share flow-20.0%

24 buying18 selling

Buying 24Unchanged 58Selling 18

Top Fund Holders

Fund

Weight

Change

Fidelity Rutland Square Trust II

312.1K

0.02%

-352.3K

FIDELITY CONCORD STREET TRUST

269.0K

0.10%

+1.0K

SCHWAB STRATEGIC TRUST

156.9K

0.05%

-2.2K

John Hancock Funds II

59.5K

0.00%

See the complete picture

The full 5D Framework: Business Quality · Peer Comparison · Valuation · Analyst Sentiment · Smart Money

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Generated August 5, 2026

For educational purposes only. Not financial advice. Data may be delayed or incomplete.

Smart Money Sentiment

CSTL Smart Money Sentiment Score

A weighted 1-5 sentiment score across three smart money signals.

Smart Money

3.3/5

Neutral

Weighted across 3 components

Component Breakdown (3 of 3 available)

Insider Activity

40% weight

Institutional Flow

50% weight

+22

Fund Flow

10% weight

+25

Overall Smart Money sentiment of 3.3/5 (Neutral) based on a weighted combination of 3 components. Insider activity uses a relative-baseline comparison against the stock's own history; institutional flow tracks position momentum and 13F share changes; fund flow measures ETF / mutual-fund buying vs selling. Higher scores indicate stronger bullish sentiment from professional investors.Last updated August 4, 2026.

Insider Trading Activity

Insider trading analysis comparing the latest quarter against the stock's own historical baseline.

Insider Activity for CSTL

Net insider share flow by quarter (C-suite & director purchases minus sales)

Neutral

Routine insider selling in Q3 2026

18 sales totaling $722.3K (29.9K shares)

Share volume is below the historical pace (0.4x average)

Sell-only pattern: no insider purchases across 7 quarters

Steady selling pace across recent quarters

Notable Recent Transactions, CSTL

Top 8 highest-value recent insider trades

MAETZOLD DEREK J

Director

Sell

43,019 shares at $19.50

Aug 13, 2025$839.04K

MAETZOLD DEREK J

Director

Sell

18,513 shares at $38.75

Dec 15, 2025$717.32K

Oelschlager Kristen M

Officer

Sell

18,932 shares at $35.10

Nov 11, 2025$664.51K

MAETZOLD DEREK J

Director

Sell

23,179 shares at $25.28

Mar 12, 2026$585.94K

Oelschlager Kristen M

Officer

Sell

14,888 shares at $39.31

Dec 17, 2025$585.29K

Juvenal Tobin W

Officer

Sell

20,863 shares at $25.24

Mar 12, 2026$526.58K

Juvenal Tobin W

Officer

Sell

13,200 shares at $37.48

Dec 11, 2025$494.74K

MAETZOLD DEREK J

Director

Sell

12,821 shares at $38.55

Dec 16, 2025$494.30K

Institutional Ownership Analysis

Institutional ownership analysis with position momentum, 13F share flow, and ownership percentage trends.

Institutional Ownership Over Time for CSTL

Total dollar value invested by institutions each quarter

Bullish Signal

Institutions accumulating in Q1 2026

92.4% institutional ownership

Slight accumulation: 129 adding vs 99 reducing

13F shares increased by 1.1%, a modest change

Momentum weakening from prior quarter

Position Changes

Q2 2026: how are institutions adjusting their positions?

+20 growing-166 shrinkingNet: -146

153

New (3)

Increased (17)

Reduced (13)

Closed (153)

Top Institutional Holders, CSTL

Largest 8 institutional positions by ownership percentage as of Q2 2026

PRINCIPAL FINANCIAL GROUP INC

1.7M

$41.2M

Ownership

5.78%

-2.4%

WASATCH ADVISORS LP

279.3K

$6.7M

Ownership

0.93%

-38.6%

KORNITZER CAPITAL MANAGEMENT INC /KS

264.2K

$6.3M

Ownership

0.88%

-0.1%

NEW YORK STATE COMMON RETIREMENT FUND

234.7K

$5.6M

Ownership

0.79%

+0.7%

ENVESTNET ASSET MANAGEMENT INC

55.2K

$1.3M

Ownership

0.18%

-10.8%

Y-INTERCEPT (HONG KONG) LTD

31.9K

$761.2K

Ownership

0.11%

+35.8%

STRS OHIO

30.5K

$727.4K

Ownership

0.10%

+22.0%

TRUIST FINANCIAL CORP

23.8K

$567.3K

Ownership

0.08%

+0.0%

ETF and Mutual Fund Holdings

ETF and mutual fund activity breakdown showing buying vs selling funds, top fund holders, and detailed holdings.

Fund Activity

Q2 2026: 100 ETFs and mutual funds reporting

24 buying18 sellingNet: +6

Buying (24)

Unchanged (58)

Selling (18)

Bullish Signal

Funds accumulating in Q2 2026

100 ETFs and mutual funds reporting

24 buying vs 18 selling (balanced)

Top Fund Holders, CSTL

Largest 8 ETF and mutual fund positions by shares held as of latest filing

Fidelity Rutland Square Trust II

312.1K

Weight

0.02%

Decreased

FIDELITY CONCORD STREET TRUST

269.0K

Weight

0.10%

Increased

SCHWAB STRATEGIC TRUST

156.9K

Weight

0.05%

Decreased

John Hancock Funds II

59.5K

Weight

0.00%

No change

VANGUARD WELLINGTON FUND

44.2K

Weight

0.01%

Increased

BNY Mellon Strategic Funds, Inc.

40.6K

Weight

5.41%

No change

iSHARES TRUST

35.9K

Weight

0.00%

Decreased

Goldman Sachs ETF Trust

35.6K

Weight

0.02%

Decreased

Castle Biosciences, Inc.· CSTL

Holdings Analysis

Insider Trading Activity

1.3Transaction History293Real market purchases and sales onlyShow All Types

Institutional Ownership Analysis

2.4Detailed Holdings62Most recent institutional positions with changes and valuations

ETF and Mutual Fund Holdings

3.3Fund Holdings Details25Most recent ETF and mutual fund holdings with share counts and weights

Search stocks

Holdings Analysis

Insider Trading Activity

1.3Transaction History293Real market purchases and sales onlyShow All Types

Institutional Ownership Analysis

2.4Detailed Holdings62Most recent institutional positions with changes and valuations

ETF and Mutual Fund Holdings

3.3Fund Holdings Details25Most recent ETF and mutual fund holdings with share counts and weights