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CASTLE BIOSCIENCES, INC.

CSTL · Healthcare · $733M mkt cap · FY2025 filings · · not refreshed in 35 days · Shallow moat ·

Doesn't clear the bar

Shallow moat
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The five investor questions

60

2021–2025 (latest 5 aligned FYs; v3 window cap 5): revenue $94.1M to $344M, increasing; diluted EPS -1.24 to -0.83, increasing. Latest-filed diluted EPS remains usable for Business Trend, but an integer share-count change lacks enough evidence to confirm a comparable EPS basis; valuation growth therefore stays at 0%.

99

Median gross margin 80.7% over 8y, very stable.

5

Median ROIC -18.4%, above the 12% hurdle in 14% of years.

55

Net cash position — no leverage risk.

24

Owner earnings changed trend unclear over up to the ten most recent annual observations.

Price vs. value if growth stopped today

A cautious baseline, not a price target: what the shares may support if normalized owner earnings simply hold steady.

Above value if growth stopped todayBelow value if growth stopped today
No price data
Not reported
Unavailable — insufficient owner-earnings data
Unavailable — insufficient growth-model data
$24.68
No price data

This zero-growth estimate assumes trailing owner earnings persist — unreliable for declining businesses. The recent FY revenue series does not trigger the three-consecutive-declines flag.

Among the current top-score group, the median current price is 239% above the zero-growth estimate across 48 of the current top 50 companies by Moat Score with both values.

Score records captured Jul 26, 2026.

Exactly which 50 companies?

FTNT, META, MEDP, IBEX, MSFT, GOOGL, LULU, ANF, IDXX, TXRH, FHI, QLYS, FFIV, ADBE, LLY, MANH, VEEV, GRMN, SSD, MNST, DOCS, MCO, CPRT, NTAP, LRCX, NVDA, CORT, SFM, MPTI, ULTA, SN, RMD, ROL, PAYC, IRMD, INTU, DECK, MORN, LGCY, DAL, GWW, ISRG, MPWR, CTAS, LOPE, MRK, CMG, FAST, BKNG, ORLY

Missing a usable price or zero-growth estimate: ANF, BKNG.

Model details under moat-index@3.0.0: zero-growth multiple 11.1×, capped-growth comparison at no more than 18×; 9% discount rate; high-end growth 0% (capped at 4%) using min(5y revenue CAGR, 5y diluted-EPS CAGR), clamped to 0%–4%; maintenance capex uses min(capex, D&A); abstain when D&A is unavailable. This is a disclosed model range, not intrinsic value as fact.

9 years of fundamentals

The business, in plain English

CASTLE BIOSCIENCES, INC. booked $344M of revenue in FY2025 in the Healthcare sector and kept 79.4% of it as gross profit — a high-margin business by that measure. After every other cost, −7.0% of each revenue dollar reached the bottom line.

Across the filed record, revenue grew from $22.8M (FY2018) to $344M (FY2025) — about 47.4% a year compounded over 7 years.

It earned −9.3% on invested capital in the latest filed year, FY2025. Across the full 7-year measurable filed record, median ROIC was −18.4%. Over the v3 recent window (7 measurable filed years), median ROIC was −18.4%. The Returns on Capital filter above scores it 5/100.

The balance sheet carried $10.1M of total debt in FY2025. Balance-Sheet Safety scores it 55/100.

Put together: Pricing Power is the strongest of the five filters (99/100) and Returns on Capital the weakest (5/100), which is how CSTL lands at 49/100 — a Shallow moat.

This breakdown is generated from the filed numbers and sub-scores above — no outside narrative, no estimates. Where a filing doesn’t disclose an input, the sentence that would need it is omitted instead of guessed.

FY2017–FY2025 · 9 fiscal years, normalized from CSTL’s SEC filings

Sales, as filed$344M FY2025
$0$200M2017202020232025
Revenue kept after cost of goods79.4% FY2025
0%50%2017202020232025
Standard ROIC or separately labeled Operating ROICROIC −9.3% FY2025

Not meaningful FY2018: invested capital is negative (cash exceeds debt + equity)

−100%0%2017202020232025
Cash an owner could take out−$19.4M FY2025
−$50M$02017202020232025

The explained ROIC gaps have filed inputs but no meaningful positive invested-capital denominator. Other gaps mean the item is not in the filings for that year. The series is never interpolated or estimated. The Table view lists every filed value, including operating and net margins, total debt, and share count.

Flagship explainer

How CASTLE BIOSCIENCES, INC. makes its money

Start with a dollar of revenue and follow what the filing says remains.

revenueBranching filed flows with values and percentages directly labeled. Missing filing concepts are omitted rather than estimated.Revenue$344M · 100%Cost of revenue$71M · 21%Gross profit$273M · 79%Operating income−$42.8M · −12%Income before tax−$29.5M · −9%Income tax−$5.4M · −2%Net income−$24.2M · −7%As of 2025-12-31 · 1 SEC filing sourceBuy Like Buffett · buylikebuffett.com

Honest partial: the filing did not provide a normalized tag for Research and development, Selling, general and administrative; those components are omitted, not plugged.

Table alternative
Filed lineValue% of revenueSource
$344M100%
Cost of revenue$71M21%
$273M79%
−$42.8M−12%
Income before tax−$29.5M−9%
Income tax−$5.4M−2%
−$24.2M−7%
Source: · event Dec 31, 2025 · retrieved Jul 26, 2026 · annual-row source set
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Flagship explainer

What CASTLE BIOSCIENCES, INC. owns — and owes

CASTLE BIOSCIENCES, INC.'s filing tags don't support a full breakdown — here's what is filed:

Table alternative
Filed lineValue% of assetsSource
Total assets$579M100%
Cash and equivalents$117M20%
$10.1M2%
Stockholders’ equity$471M81%
Source: · event Dec 31, 2025 · retrieved Jul 26, 2026 · annual-row source set

Flagship explainer

What drives CASTLE BIOSCIENCES, INC.’s return on equity?

ROE is five filed business factors multiplied together.

DuPont return on equity factor treeReturn on equity branches into tax burden, interest burden, operating margin, asset turnover, and the equity multiplier.Return on equity−5%Tax burden82%net income ÷ pretax incomeInterest burden69%pretax ÷ operating incomeOperating margin−12%operating income ÷ revenueAsset turnover0.62×revenue ÷ average assetsEquity multiplier1.20×average assets ÷ average equityAs of 2025-12-31 · 1 SEC filing sourceBuy Like Buffett · buylikebuffett.com
DuPont source inputs
InputValueFiscal yearSource
−$24.2MFY2025
Income before tax−$29.5MFY2025
Operating income−$42.8MFY2025
$344MFY2025
Ending assets$579MFY2025
Beginning assets$531MFY2024
$471MFY2025
$456MFY2024
Source:
  • SEC filingFiling detailsAccession 0001628280-26-012272
· event Dec 31, 2025 · retrieved Jul 26, 2026 · annual-row source set
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Flagship explainer

Where CASTLE BIOSCIENCES, INC.'s cash went

CASTLE BIOSCIENCES, INC.’s filing does not supply enough provenance-matched cash-flow lines for a truthful flow chart — here’s what is filed:

Table alternative
Filed lineValue% of cash from operationsSource
Cash from operations$64.3M100%
Depreciation and amortization$40.8M63%
Source: · event Dec 31, 2025 · retrieved Jul 26, 2026 · annual-row source set

Curated 19-manager tier

Who reported holding CASTLE BIOSCIENCES, INC.

Delayed public 13F reports for 2026-Q2—not live positions, trades, or recommendations.

0 holding0 exited0 not holding0/19 resolved19 not retrieved

Named manager positions and quarter-over-quarter changes
ManagerReported positionQuarter-over-quarterFiling accession
Abrams CapitalNot retrievedComparison not retrievedFiling not retrieved
Akre CapitalNot retrievedComparison not retrievedFiling not retrieved
Baupost GroupNot retrievedComparison not retrievedFiling not retrieved
Berkshire HathawayNot retrievedComparison not retrievedFiling not retrieved
Brave Warrior AdvisorsNot retrievedComparison not retrievedFiling not retrieved
Dodge & CoxNot retrievedComparison not retrievedFiling not retrieved
First EagleNot retrievedComparison not retrievedFiling not retrieved
FundsmithNot retrievedComparison not retrievedFiling not retrieved
Gardner Russo & QuinnNot retrievedComparison not retrievedFiling not retrieved
Gates Foundation TrustNot retrievedComparison not retrievedFiling not retrieved
Mairs & PowerNot retrievedComparison not retrievedFiling not retrieved
Markel / Markel-GaynerNot retrievedComparison not retrievedFiling not retrieved
Oakmark / Harris AssociatesNot retrievedComparison not retrievedFiling not retrieved
Pershing SquareNot retrievedComparison not retrievedFiling not retrieved
Polen CapitalNot retrievedComparison not retrievedFiling not retrieved
Sequoia / Ruane CunniffNot retrievedComparison not retrievedFiling not retrieved
Southeastern Asset ManagementNot retrievedComparison not retrievedFiling not retrieved
Tweedy, BrowneNot retrievedComparison not retrievedFiling not retrieved
Yacktman Asset ManagementNot retrievedComparison not retrievedFiling not retrieved

Position size uses shares and filed value from each manager’s 13F. Portfolio weight uses the eligible long-share filing denominator. Changes compare only with the immediately preceding calendar quarter.

Source: Filing source not retrieved · event Jun 30, 2026 · retrieved Jul 26, 2026

Flagship explainer

What CASTLE BIOSCIENCES, INC. insiders reported

We could not retrieve insider activity for this rendering; no zero-activity claim is shown.

Unavailable: Form 4 activity could not be retrieved for this rendering.

Moat Score history

15 logged readings since Jul 17, 2026 · append-only, never rewritten

Moat Score over timeLast scored reading of each day, on the 0–100 scale48.5 / 100
0406080100WideNarrowShallowNo moatJul 17, 2026Jul 26, 2026

Breaks in the line mark methodology or normalizer upgrades — readings across versions aren’t compared, so a level shift there isn’t a change in the business.

Tier changesSame-methodology and same-normalizer crossings of the Wide / Narrow / Shallow bars

  1. Normalizer upgraded unstamped (version unknown)moat-xbrl-normalizer@1.1.0 — readings across versions aren’t comparedJul 26, 2026
  2. Methodology upgraded moat-index@2.0.0moat-index@3.0.0 — readings across versions aren’t comparedJul 23, 2026
  3. Methodology upgraded moat-index@1.2.0moat-index@2.0.0 — readings across versions aren’t comparedJul 20, 2026

Scores are logged append-only and never overwritten — this record cannot be reconstructed retroactively, which is exactly why it’s worth keeping.

Insider activity

Form 4 reports mix P/S market or private transactions with compensation-plan mechanics. Activity casually described as “insider selling” can include compensation mechanics; awards, tax withholding, and option exercises are shown by their exact filed class here, never collapsed into “Bought” or “Sold.”

These are disclosed filing facts and arithmetic aggregates, not a signal or verdict.

The insider-filing service is temporarily unavailable, so no partial or guessed answer is shown for CSTL.

Track record

How CASTLE BIOSCIENCES, INC.’s moat rated in each of the years we can reconstruct from its filings — scored only on what was knowable at the time — and what its price and returns did afterward. The score never saw a price; the two are joined only in hindsight, for education, not as a signal.

Point-in-time scores 2019–2025, one methodology version · reconstructed from filings on file each Dec 31 — never with hindsight

Point-in-time Moat Score (dot colored by tier)Indexed price (total-return (dividends reinvested))Rated Wide-moat that year

How to read this: each dot is what the engine would have scored CSTL on that December 31; the line below is its total-return price path (dividends reinvested) in the years since.

0406080100WideNarrowShallowNo moatPoint-in-time Moat Score100200Indexed price · log scale (2020 = 100)20192021202320252026

Two tracks, one timeline: the score has its own 0–100 scale (top), the price its own 100-based scale (bottom) — never a shared axis. The price path is a total-return (dividends reinvested) index built from the same data the forward returns use; gaps in the score line are years with no reconstructed rating (see the table for why). The Table view carries every value.

What followed, in the years it rated Wide

In the reconstructed history shown, CSTL did not rate Wide-moat in any year, so there is no wide-moat track record to report. That absence is itself the honest answer — we don’t manufacture a comparison where the rating never earned one.

Healthcare context

#205 of 710 scored Healthcare companies, ranked by Moat Score.

Nearest peers by Moat Score

  1. #203LXRX Lexicon Pharmaceuticals, Inc.48.5Shallow moat
  2. #204AYTU AYTU BIOPHARMA, INC48.5Shallow moat
  3. #206MMED MiniMed Group, Inc.48.5Shallow moat
  4. #207SGHT SIGHT SCIENCES, INC.48.4Shallow moat

Compare CSTL with its nearest peers →All Healthcare companies on the Index →

Common questions about CSTL

Does CASTLE BIOSCIENCES, INC. have an economic moat?
Based on its FY2025 SEC filings, the Moat Index scores CASTLE BIOSCIENCES, INC. (CSTL) 48.5 out of 100 — a Shallow moat. The five questions behind that score begin at 20% each; if exactly one genuinely lacks data, the other four weights are renormalized and disclosed. revenue and EPS trend 60, pricing power 99, returns on capital 5, balance-sheet safety 55, capital allocation 24.
How has CSTL's Moat Score changed over time?
The record logs 15 readings since Jul 17, 2026; the latest reads 48.5 out of 100 (shallow moat). No tier changes on record yet. (Methodology or normalizer upgrades on Jul 20, 2026, Jul 23, 2026, Jul 26, 2026 re-based the score; readings across versions aren't compared.) The history is append-only — readings are only ever added, never rewritten.

Scored from primary SEC filings via the public methodology. Educational only — not a recommendation to buy or sell CSTL. See the disclaimer.