undamentalytics Newsletter
Sign in

Castle Biosciences Inc (CSTL) stock

Add to watchlist

Add holding +

NASDAQ: CSTL Nasdaq Life Sciences Tools & Services Next results ~November 5, 2026

B Fundamentals grade

Castle Biosciences Inc is a US-listed company in the life sciences tools & services industry. Its financial year ends in December.

Stock price today

Loading chart…

Third-party market data · may be delayed

Model estimate per share

~$24

Valuation models combined (3)

Base case. Range ~$18–$41. Weighted average of 3 models (growth cash-flow model, forward price-to-sales vs peers, revenue-to-maturity model), the growth cash-flow model counting double.

Price vs value

No Buy/Hold/Sell rating is issued: valued with our growth model, which doesn't carry a Buy/Hold/Sell rating yet.

Castle Biosciences Inc valuation: adjust assumptions and compare models →

Who’s trading

What company insiders, investment funds and members of Congress have been doing with the stock, from their own filings.

  • Insiders0 buying, 5 selling0 purchases and 170 sales by directors and officers, last 12 monthsInsider trades
  • Funds99 adding, 86 cuttingOf 38 active managers that changed their stake, 20 added; quarter to June 30, 2026Fund buyers and sellers

Value diary

Our note on each quarter Castle Biosciences files

Where Castle Biosciences stands after its latest 10-Q

Revenue for the twelve months to June 2026 was $357m, up 3.2% on a year earlier, against a decline of 2.1% a quarter earlier. Free-cash-flow margin fell to -0.1% from 10.0% a year earlier. Operating margin narrowed to -9.0% from -6.7%. Against its peers on growth, profitability, cash generation and balance sheet, it grades C+. It passes 5 of our 6 financial-health checks. Our revenue-to-maturity cash-flow model value is $17.53 a share, against a share price of $37.68.

Source: 10-Q filed July 30, 2026 on SEC EDGAR · Financials · Valuation

Written from the company's filings and our models when each quarter's report arrives. Figures in older notes are as published at the time. Not investment advice.

The Fundamentalytics view

Next results ~November 5, 2026 (estimated)

Castle Biosciences Inc's trailing-twelve-month revenue grew 3.2% year on year, with a free-cash-flow margin of -0.1%. Where it stands out: gross margin of 77.3% ranks 3 of 45 life sciences tools & services companies we cover.

Current signal Results well ahead of expectations: Reported earnings per share beat the analysts' consensus estimate by 83% in the quarter to 2026-06-30, the 3rd beat in the last four quarters.

Assembled from SEC-filed figures — the full workings are on this page and in our methodology. Observations, not recommendations.

Highlights

How we pick these

Strengths

  • Growth speeding up. The growth rate is 5.2 points higher than a quarter earlier.
  • Net cash. Cash exceeds long-term debt by $0.1bn.

Things to watch

  • Loss-making. Operating margin is -9.0%: costs exceed revenue.
  • Burning cash. Free cash flow was -0.1% of revenue over the last 12 months.
  • Volatile shares. Over the past year the shares showed annualised volatility of 58% and a beta of 1.0 against the S&P 500.
  • Insiders selling. 5 insiders sold $19M of stock over the past 365 days and none bought (84% under pre-set trading plans).
  • Gross margin slipping. Gross margin is down 3.7 points on a year ago.

Latest results: FY2026 Q2

Filed July 30, 2026
Earnings per share
-$0.07 against an average estimate of -$0.41: beat by 82.8%
Revenue
$104m, up 20.1% on a year earlier
Share reaction
+14.5% in the first session after the results on July 30, 2026, against +2.4% for the S&P 500
Guidance given
total revenue $365m to $375m (2026)
Next report
November 5, 2026; average EPS estimate -$0.35

Castle Biosciences' figures from its SEC filings and results release; estimates are the analysts' average. Not a recommendation.

Price chart

  • 1 day-6.0%
  • 1 week+4.9%
  • 1 month-1.7%
  • This year-10.2%
  • 1 year+37.0%
  • 5 years-43.7%
  • S&P 500 this year+11.2%

Closing prices to 2026-11-02. Price change only, dividends excluded.

Loading chart…

Third-party market data · may be delayed

At a glance

Trailing twelve months, from SEC filings

Profitability

Revenue (TTM)
$357M
Operating margin
-9.0%
Net margin
-5.4%
EPS (TTM, diluted)
$-0.66

Growth

Revenue growth
+3.2%
Change in growth rate
+5.2 pts
Share count change
−0.7%

Cash

Free cash flow (TTM)
-$489,000
FCF margin
-0.1%
Stock pay % of revenue
12.6%

Earnings

Last results
July 30, 2026

News & updates

Updated October 31, 2026

Company announcements, filed results and changes that matter to shareholders.

  1. Results
  2. Guidance

Refreshed hourly when new source data is available. Summaries are checked against company releases and SEC filings. Company announcement headlines are labelled when a checked summary is unavailable.

Valuation

Castle Biosciences Inc valuation models and calculator

Fundamentalytics rating

model v1.6 · 2026-11-03

Not rated: valued with our growth model, which doesn't carry a Buy/Hold/Sell rating yet.

Valuation models

We value Castle Biosciences Inc as an operating company, with every model that fits that kind of business. Cost of equity 9.1%: the 10-year Treasury yield (4.9%) plus a beta of 0.93 times a 4.5% equity risk premium.

Value per share by model
Model Value per share In the combined value?
Growth cash-flow model Revenue for this year and next from analysts' consensus, then growth fading to 2.5%; the operating margin moving to profitable peers'; investment needed per dollar of growth from peers; reduced by a failure probability. For young or fast-growing companies. The starting margin is normalized to between -100% and 60%; net margin is a proxy when operating income is not tagged. Uses analysts' consensus estimates (third-party data), not our forecasts. ~$22 ~$17–$26 Primary model, counts double
Price-to-earnings vs peers Earnings per share times peers' typical (harmonic-mean) price-to-earnings. — Does not apply: no positive earnings in the latest twelve months
Residual income Book value plus the present value of returns above the cost of equity, fading over ten years. — Does not apply: the model gives no positive value
Justified price-to-book Book value times (return on equity - growth) / (cost of equity - growth): steady-state returns. — Does not apply: return on equity is not positive
Forward price-to-sales vs peers Next year's consensus sales per share times peers' typical forward price-to-sales; only when earnings are negative. Uses analysts' consensus estimates (third-party data), not our forecasts. ~$41 ~$33–$97 Included, half weight
Revenue-to-maturity model Revenue grown to maturity with the cash margin moving to the industry's; for companies not yet profitable. ~$18 ~$16–$20 Included
Combined value Weighted average of the models that apply: the primary model (growth cash-flow model) counts double. Models more than 5x or less than 0.2x the share price, or more than 3x away from the other models' median, are left out. ~$24 ~$18–$41 3 models

Different models fail in different ways, so where several apply we average them rather than trust one. Peer-based models compare Castle Biosciences Inc with Life Sciences Tools & Services in our coverage, using third-party market data. Model values are estimates under stated assumptions, updated as new filings arrive; not price targets or investment advice. How each model works.

Valuation multiples over time Market data may be delayed

At fiscal year end 2019202020212022202320242025Now
Share price$34.37$67.15$42.87$23.54$21.58$26.65$38.90$34.94
Market value$298m$1.3bn$1.1bn$613m$578m$780m$1.1bn$1.0bn
+ Net debt (− = net cash)−$72m−$410m−$330m−$123m−$99m−$110m−$107m−$52m
Enterprise value$225m$861m$748m$490m$480m$670m$1.0bn$979m
Multiples
Price / sales 5.7x20.3x11.5x4.5x2.6x2.3x3.3x2.9x
Price / earnings 56.4x————42.7x——
Price / free cash flow 49.0xn/m———21.3x39.8x—
EV / EBITDA 29.3x————27.2x——

Market value uses the period's diluted share count; figures for each fiscal year use that year's results and the price at year end. "Now" uses today's price and the last twelve months.

Moat

32 /100

Weak moat

How hard Castle Biosciences's competitive advantage looks for rivals to wear away, judged from 8 years of its own filings: returns on capital, pricing power, profit durability, cash conversion and discipline.

  • Returns on capital 4 / 20

    Cash operating profit has been a median 4.9% of total assets over 7 years.

  • Pricing power 19 / 20

    Gross margin has been a median 81.4%, moving by 3.3 percentage points (standard deviation) across 8 years.

  • Durability 10 / 20

    Operating margin has been a median -7.8%; its worst year was -57.9%.

  • Cash conversion 4 / 20

    Free cash flow was positive in 3 of 8 years, at a median -5.6% of revenue.

  • Discipline 0 / 20

    The diluted share count rose 32.0% over five years; stock-based pay has been a median 15.6% of revenue.

AI disruption exposure: Medium. In this industry, AI could change how the product is made or sold, without replacing the core asset. The score above includes a 5-point deduction for that exposure (37 before it).

A rules-based reading of reported figures, not a forecast and not investment advice. How the score is built: methodology.

Forecasts and guidance

Next results: November 5, 2026, after the close. Analysts expect revenue of $93m and EPS of −$0.35 (range −$0.42 to −$0.25) for the quarter.

Analysts' consensus

Fiscal yearEPSGrowthRevenueGrowth
Current −$1.25 −50% $374m +9%
Next −$0.94 +25% $419m +12%

How the EPS forecast has moved

The consensus EPS forecast for the current fiscal year is −5.8% on 90 days ago. In the last 30 days, 1 analyst raised Castle Biosciences Inc's forecast and 0 cut it.

Consensus EPS forecast Castle Biosciences Inc, last 90 days
−$1.50 −$1.00 −$0.50 $0.00 90 days ago 60 days ago 30 days ago 7 days ago Now Current fiscal year, 90 days ago: −$1.32 Current fiscal year, 60 days ago: −$1.27 Current fiscal year, 30 days ago: −$1.27 Current fiscal year, 7 days ago: −$1.26 Current fiscal year, Now: −$1.25 −$1.25 Next fiscal year, 90 days ago: −$1.03 Next fiscal year, 60 days ago: −$0.99 Next fiscal year, 30 days ago: −$0.94 Next fiscal year, 7 days ago: −$0.91 Next fiscal year, Now: −$0.94 −$0.94

Average of analysts' published estimates (third-party data).

View chart data
Period Current fiscal yearNext fiscal year
90 days ago −$1.32−$1.03
60 days ago −$1.27−$0.99
30 days ago −$1.27−$0.94
7 days ago −$1.26−$0.91
Now −$1.25−$0.94

Earnings against estimates

Quarter toEstimateActualSurprise
Jun 2026 −$0.41 −$0.07 +82.8%
Mar 2026 −$0.49 −$0.49 −0.3%
Dec 2025 −$0.26 −$0.08 +69.1%
Sept 2025 −$0.51 −$0.02 +96.1%

Adjusted EPS as companies report it, against the average analyst estimate.

Management guidance

Earnings release, July 30, 2026
  • total revenue 2026 $365m to $375m Raised
    “The Company now anticipates generating between $365-375 million in total revenue in 2026, compared to the previously provided guidance of between $345-355 million.” source

Figures and quotations are management's, copied from the company's own press release (SEC 8-K exhibit) and checked word for word against it. Forward-looking statements are the company's expectations, not ours and not advice; guidance can change or be missed.

Analyst recommendations

10 analysts, Oct 2026
Buy10100%
Hold00%
Sell00%

Monthly trend

  1. Oct 20261010
  2. Sep 202699
  3. Aug 202699
  4. Jul 202699

Counts of recommendations published by analysts covering Castle Biosciences Inc, by month. Source: Aggregated broker recommendations (third-party data). Aggregated counts only: we do not reproduce any firm's recommendation or price target, and these are not Fundamentalytics ratings.

Positioning

Short interest
6.8%
of tradable shares
Days to cover
5.17
at average volume
Short interest, 1 month
+6%
to October 15, 2026
Held by institutions
91%
of shares
Held by insiders
2.3%
of shares
Employees
1,002
full time

Consensus figures average analysts' published estimates (third-party data); guidance is the company's own. Neither is our forecast. Short interest is reported twice a month and lags. Market data may be delayed.

This section is general information, not investment advice or a personal recommendation, and it does not take account of your objectives or circumstances. Forecasts and guidance are estimates, not promises: companies miss their own guidance and analysts' figures are often revised. Prices can fall as well as rise, and you can lose money. See our disclaimer.

Share-price performance

Market data may be delayed

What moved the share price

Last 12 months +37.0%

$25.50 on October 31, 2025 to $34.94

ThenNowEffect
Revenue (last 12 months) $346m $357m +3.2%
P/S multiple 2.2x 2.9x +31.8%
Share count 30m 30m +0.7%

Biggest factor: p/s multiple. Loss-making at one end, so the split uses price/sales.

Last 3 years +94.3%

$17.98 on November 3, 2023 to $34.94

ThenNowEffect
Revenue (last 12 months) $168m $357m +113.3%
P/S multiple 2.8x 2.9x +1.4%
Share count 27m 30m −10.2%

Biggest factor: revenue. Loss-making at one end, so the split uses price/sales.

The effects multiply back to the price change exactly. Results are the last 12 months as known on each date (filings assumed public 45 days after quarter end).

Return and risk by year

Calendar year 202120222023202420252026 to date
Return
CSTL−36%−45%−8%+24%+46%−10%
Industry peers (median)+5%−53%−3%−15%−7%+16%
S&P 500+29%−18%+26%+25%+18%+11%
Months that ended higher
CSTL42%42%50%50%50%55%
S&P 50075%42%67%75%75%46%
Largest fall from a high during the year
CSTL−60%−66%−59%−31%−55%−58%
S&P 500−5%−25%−10%−8%−19%−9%

Worst fall since July 25, 2019: 88% from February 9, 2021 to June 5, 2023. Getting back needed a 735% gain, and the shares have not yet recovered.

Price behaviour

52-week range
$18.15 – $43.04
From 52-week high
−18.8%
vs 50-day average
+2.1%
vs 200-day average
+22.6%
Volatility (1 year)
58%
Beta vs S&P 500
0.97

Volatility is the annualised standard deviation of daily returns. Beta 1.5 means the shares typically moved 1.5% for each 1% move in the S&P 500 over the past year. Prices to November 2, 2026.

Share price after results

Next day
6 up, 6 down
typical move ±15.1%
After a week
7 up, 5 down
typical move ±17.3%
After a month
5 up, 7 down
typical move ±24.2%
Results releasedNext dayS&P 500 next day5 days21 days
July 30, 2026 +14.5% +2.4% +24.6% +37.0%
May 6, 2026 −21.8% +1.1% −26.2% −14.6%
February 26, 2026 −4.1% −1.0% −9.5% −23.7%
January 13, 2026 +2.8% −0.7% +3.3% −19.6%
November 3, 2025 +24.0% −1.0% +36.2% +54.5%
August 4, 2025 +38.9% +1.0% +30.8% +58.4%
May 5, 2025 −14.1% −1.4% −11.9% −12.0%
February 27, 2025 −16.7% −0.1% −20.9% −23.4%
January 13, 2025 −15.8% +0.3% −11.7% −7.9%
November 4, 2024 −6.0% +1.0% +1.9% −3.8%
August 5, 2024 +11.8% −2.0% +20.1% +29.8%
May 2, 2024 +10.5% +2.2% +10.9% +6.3%

From the close before the release date to the close 1, 5 and 21 trading days after it, so releases before the open and after the close are both captured. Past moves don't predict future ones.

Castle Biosciences Inc in five measures

Fundamentals grade B
Growth Profitability Cash Balance sheet

Growth, profitability, cash generation and balance sheet are percentiles against the companies we cover in the same industry, from SEC filings (100 = best). Value compares the share price with our modelled value range (50 = at our base value; higher = cheaper). A description of reported data and our model — not a quality score or advice.

Fundamentals

Revenue (TTM) Castle Biosciences Inc
$150M $200M $250M $300M $350M $400M FY23 Q3 FY24 Q2 FY25 Q1 FY26 Q2 Revenue (TTM), FY23 Q3: $192M Revenue (TTM), FY23 Q4: $219.8M Revenue (TTM), FY24 Q1: $250.7M Revenue (TTM), FY24 Q2: $287.6M Revenue (TTM), FY24 Q3: $311.9M Revenue (TTM), FY24 Q4: $332.1M Revenue (TTM), FY25 Q1: $347.1M Revenue (TTM), FY25 Q2: $346.3M Revenue (TTM), FY25 Q3: $343.5M Revenue (TTM), FY25 Q4: $344.2M Revenue (TTM), FY26 Q1: $339.9M Revenue (TTM), FY26 Q2: $357.3M $357.3M

Source: SEC EDGAR filings. Retrieved October 29, 2026.

View chart data
Period Revenue (TTM)
FY23 Q3 $192M
FY23 Q4 $219.8M
FY24 Q1 $250.7M
FY24 Q2 $287.6M
FY24 Q3 $311.9M
FY24 Q4 $332.1M
FY25 Q1 $347.1M
FY25 Q2 $346.3M
FY25 Q3 $343.5M
FY25 Q4 $344.2M
FY26 Q1 $339.9M
FY26 Q2 $357.3M
Revenue growth, TTM YoY Castle Biosciences Inc
-20% 0% 20% 40% 60% 80% FY23 Q3 FY24 Q2 FY25 Q1 FY26 Q2 Revenue growth, TTM YoY, FY23 Q3: 55.2% Revenue growth, TTM YoY, FY23 Q4: 60.4% Revenue growth, TTM YoY, FY24 Q1: 64.7% Revenue growth, TTM YoY, FY24 Q2: 71.7% Revenue growth, TTM YoY, FY24 Q3: 62.4% Revenue growth, TTM YoY, FY24 Q4: 51.1% Revenue growth, TTM YoY, FY25 Q1: 38.4% Revenue growth, TTM YoY, FY25 Q2: 20.4% Revenue growth, TTM YoY, FY25 Q3: 10.1% Revenue growth, TTM YoY, FY25 Q4: 3.7% Revenue growth, TTM YoY, FY26 Q1: -2.1% Revenue growth, TTM YoY, FY26 Q2: 3.2% 3.2%

Source: SEC EDGAR filings. Retrieved October 29, 2026.

View chart data
Period Revenue growth, TTM YoY
FY23 Q3 55.2%
FY23 Q4 60.4%
FY24 Q1 64.7%
FY24 Q2 71.7%
FY24 Q3 62.4%
FY24 Q4 51.1%
FY25 Q1 38.4%
FY25 Q2 20.4%
FY25 Q3 10.1%
FY25 Q4 3.7%
FY26 Q1 -2.1%
FY26 Q2 3.2%
Operating margin (TTM) Castle Biosciences Inc
-60% -40% -20% 0% 20% FY23 Q3 FY24 Q2 FY25 Q1 FY26 Q2 Operating margin (TTM), FY23 Q3: -44.3% Operating margin (TTM), FY23 Q4: -30.9% Operating margin (TTM), FY24 Q1: -16.7% Operating margin (TTM), FY24 Q2: -5.5% Operating margin (TTM), FY24 Q3: -0.3% Operating margin (TTM), FY24 Q4: 2.6% Operating margin (TTM), FY25 Q1: -4.0% Operating margin (TTM), FY25 Q2: -6.7% Operating margin (TTM), FY25 Q3: -10.2% Operating margin (TTM), FY25 Q4: -12.4% Operating margin (TTM), FY26 Q1: -9.8% Operating margin (TTM), FY26 Q2: -9.0% -9.0%

Source: SEC EDGAR filings. Retrieved October 29, 2026.

View chart data
Period Operating margin (TTM)
FY23 Q3 -44.3%
FY23 Q4 -30.9%
FY24 Q1 -16.7%
FY24 Q2 -5.5%
FY24 Q3 -0.3%
FY24 Q4 2.6%
FY25 Q1 -4.0%
FY25 Q2 -6.7%
FY25 Q3 -10.2%
FY25 Q4 -12.4%
FY26 Q1 -9.8%
FY26 Q2 -9.0%
FCF margin (TTM) Castle Biosciences Inc
-30% -20% -10% 0% 10% 20% FY23 Q3 FY24 Q2 FY25 Q1 FY26 Q2 FCF margin (TTM), FY23 Q3: -21.8% FCF margin (TTM), FY23 Q4: -8.8% FCF margin (TTM), FY24 Q1: -2.6% FCF margin (TTM), FY24 Q2: 7.0% FCF margin (TTM), FY24 Q3: 11.1% FCF margin (TTM), FY24 Q4: 11.0% FCF margin (TTM), FY25 Q1: 12.0% FCF margin (TTM), FY25 Q2: 10.0% FCF margin (TTM), FY25 Q3: 7.4% FCF margin (TTM), FY25 Q4: 8.2% FCF margin (TTM), FY26 Q1: 1.3% FCF margin (TTM), FY26 Q2: -0.1% -0.1%

Source: SEC EDGAR filings. Retrieved October 29, 2026.

View chart data
Period FCF margin (TTM)
FY23 Q3 -21.8%
FY23 Q4 -8.8%
FY24 Q1 -2.6%
FY24 Q2 7.0%
FY24 Q3 11.1%
FY24 Q4 11.0%
FY25 Q1 12.0%
FY25 Q2 10.0%
FY25 Q3 7.4%
FY25 Q4 8.2%
FY26 Q1 1.3%
FY26 Q2 -0.1%

Data: SEC EDGAR XBRL company facts (as filed in 10-K/10-Q); forms 10-K, 10-Q. Generated November 3, 2026. Definitions in our methodology.

Financial statements

US$ millions unless shown otherwise. Fiscal years, plus the last twelve months (LTM) when newer.

Fiscal year 2018 Dec 2018 2019 Dec 2019 2020 Dec 2020 2021 Dec 2021 2022 Dec 2022 2023 Dec 2023 2024 Dec 2024 2025 Dec 2025 LTM Jun 2026
Income
Revenue 23 52 63 94 137 220 332 344 357
Gross profit 17 45 53 78 105 175 272 273 276
EBITDA −4 8 −6 −37 −62 −56 25 −2 −21
Operating income −4 7 −7 −40 −73 −68 9 −43 −32
Net income −6 5 −10 −31 −67 −57 18 −24 −19
Diluted EPS −$5.33 −$0.21 −$0.54 −$1.24 −$2.58 −$2.14 $0.62 −$0.83 −$0.66
Growth (year on year)
Revenue — +127.6% +20.8% +50.2% +45.7% +60.4% +51.1% +3.7% +3.2%
EBITDA — — −179.0% — — — — −108.3% −238.4%
Operating income — — −189.3% — — — — −593.8% —
Net income — — −294.9% — — — — −232.4% —
Diluted EPS — — — — — — — −233.9% —
Margins
Gross margin 76.8% 85.9% 84.5% 83.2% 76.6% 79.5% 81.9% 79.4% 77.3%
EBITDA margin −15.6% 14.8% −9.7% −39.0% −45.5% −25.3% 7.4% −0.6% −5.9%
Operating margin −16.8% 14.1% −10.4% −42.6% −53.2% −30.9% 2.6% −12.4% −9.0%
Net margin −27.9% 10.2% −16.4% −33.3% −49.0% −26.1% 5.5% −7.0% −5.4%
Free-cash-flow margin −55.2% 11.7% 8.2% −23.9% −34.5% −8.8% 11.0% 8.2% −0.1%
Cash flow
Cash from operations −12 7 10 −19 −42 −6 65 64 43
Capital spending 0 1 5 3 6 14 28 36 43
Free cash flow −13 6 5 −22 −47 −19 37 28 −0
Stock-based pay 0 1 8 22 36 51 50 46 45
Free cash flow after stock pay −13 5 −3 −44 −84 −70 −14 −18 −45
Balance sheet
Cash 4 99 410 330 123 99 120 117 62
Total debt 25 27 0 0 0 0 10 10 10
Net debt (negative = net cash) 20 −72 −410 −330 −123 −99 −110 −107 −52
Diluted shares 2m 9m 19m 25m 26m 27m 29m 29m 30m

Source: SEC EDGAR XBRL company facts (US and foreign periodic filings); column headings link to the filing. EBITDA is operating income plus depreciation and amortisation. Free cash flow is cash from operations minus capital spending. Growth is left blank when last year's figure was a loss or under 2% of revenue. Share counts and EPS are restated for stock splits. A dash means the company didn't report the figure.

Financial health

5 of 6 checks passed · June 30, 2026
What it owns · $561m
Short-term assets $341mLonger-term assets $220m
What it owes, and who funded it · $561m
Short-term liabilities $57mLonger-term liabilities $35mShareholders' equity $470m
  • Short-term assets cover short-term liabilities $341m of assets due within a year against $57m of liabilities due within a year.
  • Short-term assets cover long-term liabilities $341m short-term assets against $35m of longer-dated liabilities.
  • More cash than debt $62m of cash against $10m of debt.
  • Debt below 40% of shareholders' equity Debt is 2% of equity.
  • Debt burden no higher than five years ago Five-year comparison not available. Not assessable.
  • A year's operating cash flow covers at least 20% of debt $43m of operating cash flow against $10m of debt.
  • Operating profit covers interest at least five times over Operating income of −$32m against $375,000 of interest.

From Castle Biosciences Inc's latest balance sheet as filed. Checks are fixed, documented rules (methodology), counted only where the company reports the figures — a dot means the filing doesn't break the item out. Descriptions of reported data, not advice.

Dividends, buybacks and capital spending

Diluted share count
−0.7%
year over year
R&D spending
15.5%
of revenue
Sales & admin spending
68.2%
of revenue
Days sales outstanding
49 days
receivables vs revenue

Competitors: side by side with peers

Closest by revenue in life sciences tools & services
Last 12 months unless stated CSTL FLGT TWST SDGR MLAB VCYT Median
Revenue, last 12 months $357m $324m $432m $259m $250m $562m $229m
Revenue growth, last 12 months 3.2% 6.8% 19.2% 8.9% 3.0% 17.3% 6.9%
Revenue growth, 3-year average 28.7% 1.8% 22.4% 10.2% 4.4% 19.6% 2.9%
Revenue growth, latest quarter 20.1% 4.4% 23.2% 7.5% 1.0% 15.5% 8.5%
Gross margin 77.3% 35.6% 52.0% 56.9% 64.2% 71.7% 51.9%
Operating margin −9.0% −37.7% −33.6% −59.2% 9.0% 18.8% −14.3%
Operating margin, 3-year average −7.0% −42.5% −50.8% −81.0% −34.7% 1.6% −22.4%
Net margin −5.4% −26.0% −31.7% −21.0% 1.9% 20.4% −16.1%
Cash from operations / revenue 11.9% −25.8% −12.3% −49.0% 22.3% 31.7% 1.3%
Free-cash-flow margin −0.1% −32.0% −21.6% −50.3% 21.2% 29.5% −2.2%
Free-cash-flow margin, 3-year average 5.6% −15.9% −22.0% −45.4% 17.9% 19.0% 0.6%
Stock pay / revenue 12.6% 11.6% 15.4% 14.9% 6.5% 8.6% 4.4%
Change in share count −0.7% −1.5% 2.4% 1.7% 3.0% 2.5% 1.0%

Median of all 54 companies we cover in life sciences tools & services. Shaded: best of the six on that line (lowest for stock pay and share-count growth). 3-year figures average the last three 12-month periods; 3-year growth is compound annual. Source: SEC filings.

Peer comparison

54 life sciences tools & services companies
Measure Company Peer median Rank
Revenue growth Growth 3.2% 6.9% 36 of 54
Change in growth rate Growth +5.2pp +0.4pp 10 of 54
Gross margin Profitability 77.3% 52.0% 3 of 45
Operating margin Profitability -9.0% -14.3% 23 of 52
Net margin Profitability -5.4% -12.2% 23 of 54
Free-cash-flow margin Cash generation -0.1% -1.3% 26 of 54
Stock pay as % of revenue Cash generation 12.6% 4.4% 39 of 53
Long-term debt as % of assets Balance sheet 1.3% 26.3% 7 of 35
Change in share count Balance sheet -0.7% 1.0% 16 of 46
Days sales outstanding Balance sheet 49 days 62 days 13 of 48

Rank 1 = best in the group (for spending, debt and dilution, lower ranks first).

Where the revenue comes from

Fiscal year to December 31, 2025
Products and services
Line of business Revenue Share YoY
Dermatologic $216M 62.9% ▼ 15.8%
Non Dermatologic $128M 37.1% ▲ 70.3%

From Castle Biosciences Inc's 10-K filed February 26, 2026, as tagged in the filing. View filing. Indented rows are part of the line above; their share is of that line. In the bars, the faint bar behind is the year before.

Who owns it

Funds buying and selling
Reported value
$653M
Institutions reporting
176
Shares held vs prior quarter
▼ 1.0%
Positions opened / closed
20 / 30

Top buyers and sellers, Q2 2026: 99 institutions bought and 86 sold ; the biggest buyer was Mackenzie Financial Corp (+719K shares) and the biggest seller Portolan Capital Management, LLC (−1.0M). See which funds bought and sold →

Largest reported holders, June 30, 2026
Manager Value Shares Share of 13F value Shares QoQ
Blackrock, Inc. $78.5M 3.3M 12.0% ▲ 10.4%
RTW Investments, LP $66.3M 2.8M 10.2% ▲ 0.7%
Principal Financial Group Inc $41.2M 1.7M 6.3% ▼ 2.4%
Vanguard Capital Management LLC $29.3M 1.2M 4.5% ▲ 4.2%
Acadian Asset Management LLC $21.9M 919K 3.4% ▲ 89.6%
Vanguard Portfolio Management LLC $20.1M 841K 3.1% ▼ 2.4%
Allianz Asset Management Gmbh $19.9M 811K 3.1% 0.0%
Summit Partners Public Asset Management, LLC $19.7M 825K 3.0% ▼ 12.3%
State Street Corp $19.6M 822K 3.0% ▲ 6.9%
Geode Capital Management, LLC $19M 796K 2.9% ▲ 9.3%
Mackenzie Financial Corp $18.9M 794K 2.9% ▲ 970.7%
Dimensional Fund Advisors LP $18.9M 791K 2.9% ▼ 23.9%

From Form 13F filings with the SEC ( quarterly data sets), as reported by each manager for June 30, 2026 and filed up to 45 days later. 13F reports cover long US-listed positions of managers above $100M only, so this is not Castle Biosciences Inc's complete shareholder register. Values are as reported by the filers .

Insider trading activity

Full insider history and chart
Insider purchases History → $0 0 trades by 0 insiders, last 12 months Insider sales History → $19.2M 170 trades by 5 insiders · 84% under pre-set plans
Net ▼ $19.2M net selling
Insider Date Trade Shares Price Value
Juvenal Tobin W Chief Commercial Officer October 28, 2026 Sell pre-set plan 5,341 $36.62 $195,582
Juvenal Tobin W Chief Commercial Officer October 28, 2026 Sell pre-set plan 1,237 $35.58 $44,009
Juvenal Tobin W Chief Commercial Officer October 26, 2026 Sell pre-set plan 3,288 $33.08 $108,767
Maetzold Derek J Pres. & Chief Exec. Officer October 19, 2026 Sell pre-set plan 2,718 $31.91 $86,731
Maetzold Derek J Pres. & Chief Exec. Officer October 19, 2026 Sell pre-set plan 3,198 $31.91 $102,048
Maetzold Derek J Pres. & Chief Exec. Officer October 19, 2026 Sell pre-set plan 8,580 $31.91 $273,788
Juvenal Tobin W Chief Commercial Officer October 12, 2026 Sell pre-set plan 3,288 $33.64 $110,608
Maetzold Derek J Pres. & Chief Exec. Officer October 5, 2026 Sell pre-set plan 2,718 $35.57 $96,668
Maetzold Derek J Pres. & Chief Exec. Officer October 5, 2026 Sell pre-set plan 3,198 $35.57 $113,740
Maetzold Derek J Pres. & Chief Exec. Officer October 5, 2026 Sell pre-set plan 8,580 $35.57 $305,156
Oelschlager Kristen M Chief Operating Officer October 1, 2026 Sell pre-set plan 1,346 $36.38 $48,967
Oelschlager Kristen M Chief Operating Officer October 1, 2026 Sell pre-set plan 2,807 $35.75 $100,350

From insiders' Form 4 filings with the SEC. Excludes awards, option exercises and shares withheld for tax. "Pre-set plan" means the filing marks the trade as made under a Rule 10b5-1 plan. See every insider trade since five years ago, on a price chart.

Trades by members of Congress

All 3 trades and filings

No trades in Castle Biosciences Inc disclosed in the last 12 months; 3 earlier trades on record.

  • Josh Gottheimer(D-NJ 5):Sale (partial), $1,001 - $15,000, traded March 15, 2022, filed April 17, 2022
  • Gilbert Ray Cisneros, Jr.(D-CA 39):Purchase, $1,001 - $15,000, traded December 23, 2020, filed January 11, 2021
  • Josh Gottheimer(D-NJ 5):Purchase, $1,001 - $15,000, traded December 21, 2020, filed January 7, 2021

Value ranges as filed; reports can arrive up to 45 days after a trade.

Earnings dates and SEC filings

Results announcements

Next expected around October 8, 2026 estimated from the company's past filing pattern, not announced

  • July 30, 2026
  • May 6, 2026
  • February 26, 2026
  • January 13, 2026
  • November 3, 2025
  • August 4, 2025

Recent SEC filings

Data status

When each part of this page on Castle Biosciences Inc was last updated.

DataLast updatedSource
Share priceExchange closing prices
Financial statementsSEC 10-K and 10-Q filings
News and updatesCompany releases and SEC 8-K filings
Analyst estimatesAggregated analyst estimates
Valuation and scoresOur models, from the filed figures

How we build and check these figures: methodology and data sources.

Castle Biosciences Inc in brief

What does Castle Biosciences Inc do?
Castle Biosciences Inc is a US-listed company in the life sciences tools & services industry. Its financial year ends in December.
What is Castle Biosciences Inc's stock ticker?
Castle Biosciences Inc trades under the ticker CSTL on Nasdaq. This page brings together its financial statements, valuation models, ownership and recent company updates.
What is Castle Biosciences Inc's revenue, and how fast is it growing?
Over its most recent trailing twelve months, Castle Biosciences Inc reported revenue of $357M, 3.2% higher than a year earlier, according to its SEC filings.
What is Castle Biosciences Inc's free cash flow?
Castle Biosciences Inc's free-cash-flow margin is -0.1% of revenue over the trailing twelve months, ranking 26 of the 54 life sciences tools & services companies we cover.
Who are Castle Biosciences Inc's largest institutional shareholders?
By value reported in 13F filings for June 30, 2026, the largest reported holders are Blackrock, Inc., RTW Investments, LP and Principal Financial Group Inc. 13F reports cover long US-listed positions of managers above $100M, filed up to 45 days after quarter end.
What is Castle Biosciences Inc's market cap?
On November 2, 2026, Castle Biosciences Inc's market capitalisation was about $1B and net debt of -$51.9M. Market figures come from third-party market data and may be delayed.
How much debt does Castle Biosciences Inc have?
Castle Biosciences Inc's debt-to-equity ratio is 2.1%, from its latest balance sheet. The financial health section below sets out its other solvency checks.
Who are Castle Biosciences Inc's competitors?
In our Life Sciences Tools & Services peer group, the companies closest to Castle Biosciences Inc are Fulgent Genetics, Inc., Twist Bioscience Corp, Schrodinger, Inc., Mesa Laboratories Inc and Veracyte, Inc. The side-by-side comparison below sets their revenue, margins and growth against Castle Biosciences Inc's.
Are insiders buying or selling Castle Biosciences Inc stock?
Over the last 12 months, Castle Biosciences Inc's directors and officers reported 0 open-market purchases and 170 sales on Form 4. The insider trading page charts every trade.
When is Castle Biosciences Inc's next earnings date?
Around November 5, 2026, estimated from the spacing of its past results announcements (8-K filings). That is an estimate, not a confirmed date — Castle Biosciences Inc announces its own schedule.