Castle Biosciences

CSTL

Medical - Diagnostics & Research · Healthcare

Exchange

NASDAQ

Winston Score

Winston is worried

Weak fundamentals across most pillars.

Data as of Aug 23, 2026 · filings through Jun 30, 2026

How the score breaks down

Quality

Mixed

Growth

Weak

Cash Flow

Weak

Stability

Good

Valuation

Data not available

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Winston Score History

The full picture

Castle Biosciences, Inc., a commercial-stage diagnostics company, focuses to provide diagnostic and prognostic testing services for dermatological cancers. Its lead product is DecisionDx-Melanoma, a multi-gene expression profile (GEP) test to identify the risk of metastasis for patients diagnosed with invasive cutaneous melanoma.

Growth Profile

For growth stock investors

When traditional metrics don't capture the full picture, these are the signals growth stock investors use instead.

Revenue Growth

+20.1% YoY

YoY Growth Rate

Steady revenue growth

EPS Growth

-143.8% YoY

YoY Growth Rate

Earnings declining

Insider Activity

11.7%ownership

→ Flat

Insider ownership roughly steady over the past year

Cash Position

Cash flow positive

$267M cash & investments

Quarterly Free Cash Flow

↓ Burn rate worsening

Company generates more cash than it spends — no dilution risk from fundraising

Growth + cash flow

Castle Biosciences is a rare growth stock that's already generating positive cash flow while growing at 20%. The Winston Score doesn't fully credit this transition from "burner" to "earner."

The Winston Score above measures business quality today. Growth stocks often score lower because they invest in the future rather than maximising current profits. These metrics show what matters most for evaluating that future.

Score breakdown

Every number that matters to educated investors.

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Quality

Profit per sale

Gross Margin

77.1%

Premium pricing power — 77.1% gross margin

Profit after running costs

Operating Margin

-3.0%

Losing money on operations — -3.0%

Return on the money invested

ROCE

-6.7%

Weak — -6.7% return on capital

Negative ROIC means the business is losing money on every dollar invested in it.

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Growth

Sales growth

Sales YoY

+3.2%

Slow sales growth (+3.2% YoY)

Profit growth

EPS YoY

N/A

Data not available

How steady the profit is

EPS Consistency

3/8 quarters

Earnings rarely grow — volatile business

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Cash Flow

Profit that turns into cash

Cash Conversion

N/A

Data not available

Spare cash per sale

FCF Margin

-0.1%

Burning cash (-0.1%)

Free cash flow is negative. They are burning cash, not generating it.

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Stability

What it owes vs what it owns

Debt / Equity

0.02

Conservative — low debt load (0.02)

Covers its interest

Interest Cover

N/A

Data not available

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Valuation

Price vs profit

P/E Ratio (TTM)

N/M

no trend

Negative earnings — P/E not meaningful

Cheaper or dearer next year

P/E vs Forward

N/A

not available

Data not available

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Dividends

Not applicable for this business.

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