Castle Biosciences, Inc. (CSTL) Fair Value 2026

CSTL · Diagnostics & Research ·

By CirclFi Research Team · Data from SEC EDGAR, FRED & GDELT

Quality Score

7.4 /10

32 fundamental signals · 5 models active

Value Trap Risk

SAFE (6/100)

Quick Summary — As of 2026-08-27, Castle Biosciences, Inc. (CSTL) trades at $34.26, versus a $9.38 median fair value across its 5 active models — 72.6% below the current price. QOC: 7.4/10. Value Trap Risk: 6/100 (SAFE). 5/13 models active. Within that set, the Bayesian DCF component alone returns $4.34.

Key Facts

Ticker
CSTL
Price
$34.26
Quality Score
7.4/10
Value Trap Risk
6/100
Models Active
5/13
Last Updated
Strength: 5 independent models provide multi-angle coverage
Risk: Majority of models suggest overvaluation

Is Castle Biosciences, Inc. (CSTL) Undervalued or Overvalued in 2026?

According to CirclFi’s 5-model valuation engine, Castle Biosciences, Inc. (CSTL) appears overvalued as of : the median of 5 independent fair value estimates is $9.38, 72.6% below the current price of $34.26. Estimates range from $4.34 to $38.33. CSTL scores 7.4/10 on fundamental quality and 6/100 on value-trap risk.

For context, the median US equity CirclFi rates trades at an implied -23.7% versus its own 13-model consensus, across 3,801 rated companies as of 2026-08-27. CSTL’s -72.6% gap is wider than that market norm, and the Diagnostics & Research sector median is -54.1%. Full market index →

This verdict compares price to intrinsic value only — it is not a buy or sell rating. For the decision case (bull vs bear arguments, risk factors, peers), read Should You Buy Castle Biosciences, Inc. Stock in 2026? →

What Fair Value Does Each Model Give CSTL?

5 Intrinsic Value Models vs. Current Price ($34.26)

Core Models (Unlocked)
Model Fair Value Upside
Intrinsic · High Conviction
 $4.34 -87.3%
Ensemble · Low Conviction
 $11.18 -67.4%
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What Is CSTL's Fair Value Range?

Spread across 5 independent models · $4.34 to $38.33

CirclFi's 5 active models place Castle Biosciences, Inc. (CSTL) between $4.34 and $38.33 per share, a spread of 362% of the median. The median of that range — $9.38 — is the fair value CirclFi publishes for CSTL, against a current price of $34.26.

Low · Bayesian DCFHigh · FTNN
$4.34median $9.38$38.33
Where the range comes from
Most bearish modelBayesian DCF$4.34
Most bullish modelFTNN Topology$38.33
Model agreement1 bullish · 4 bearishwide

A band this wide is itself the finding. When independent methods land far apart, they are reading a business whose value depends heavily on which lens you apply — volatile earnings, heavy reinvestment, or an asset base that cash-flow and asset-based methods score differently. That disagreement is information: it says the choice of method matters more than usual for CSTL. Treat the median as one reading among several and compare the individual models below before acting.

Every figure above is one model's standalone output on CSTL, not a CirclFi price target. How each model works →

What Is Castle Biosciences, Inc. (CSTL) Worth in 2026?

According to the CirclFi Deep Alpha Valuation Engine, Castle Biosciences, Inc.'s intrinsic value is estimated at $9.38. Trading at its current price of $34.26, the valuation engine raises significant caution: 4 of 5 models flag downside risk, projecting a median implied return of -72.6%. Notably, FTNN sees the most upside at +11.9% (fair value: $38.33), while Bayesian DCF is the most conservative at -87.3% ($4.34). The spread between these extremes — +99.2% — reveals how different analytical frameworks can reach starkly different conclusions.

What Do the Models Say About CSTL?

5 of 13 models are currently active for CSTL. Of these, 1 model suggests upside while 4 models suggest overvaluation. Taken together, their median fair value for CSTL is $9.38 — the figure CirclFi publishes as this stock's fair value. One component of that median, the Bayesian DCF, returns $4.34 on its own, implying -87.3% downside from the current price. See which stocks rank higher →

How Does CSTL Rank in Diagnostics & Research?

Among 52 Diagnostics & Research stocks, CSTL ranks #19 by Quality of Company score. CirclFi's QOC score of 7.4/10 evaluates 32 fundamental signals. A score of 7.4 indicates above-average quality.

Castle Biosciences, Inc.'s positioning within the Diagnostics & Research segment means that clinical trial success rate plays an outsized role in fundamental analysis. The sector's unique characteristics — including orphan drug designation — shape both the opportunity set and risk profile.

Is CSTL a Value Trap?

CirclFi's Value Trap algorithm assigns CSTL a score of 6/100 (SAFE). This indicates minimal risk. Fundamentals are healthy. The score cross-references apparent undervaluation against fundamental deterioration signals. Browse lowest value-trap stocks →

Multi-Model Methodology

5 of 13 models are active for Castle Biosciences, Inc.. Limited activation may indicate insufficient history. Each model applies a fundamentally different valuation philosophy. See the complete methodology →

According to the CirclFi Quality of Company (QOC) framework, Castle Biosciences, Inc. earns a quality score of 7.4/10. This respectable rating reflects the company's standing across 32 fundamental signals spanning profitability, growth consistency, balance sheet strength, and capital allocation efficiency.

The gap between the most bullish and bearish model spans +99.2% — demonstrating why single-model analysis is dangerous. Browse all stocks with 13-model coverage →

Data Sources & Confidence

Every CSTL valuation is built from SEC EDGAR XBRL filings — 700+ standardized financial tags. Macroeconomic context from FRED calibrates discount rates, while GDELT news sentiment feeds into our Sentiment SOTP model. All pipelines run daily. Read the complete data methodology →

Across CSTL's 5 active models, average confidence is 37%. Lower confidence may reflect limited history or high volatility.

CirclFi's output is a research starting point, not a buy/sell signal. All data updates daily. Read the full methodology →

This analysis is produced by the CirclFi Valuation Engine using quantitative models applied to SEC EDGAR filings, public market feeds, and FRED macroeconomic indicators. It is not financial advice.

Read the full investment analysis: Should You Buy Castle Biosciences, Inc. Stock in 2026? →

Bull case, bear case, risk factors & peer comparison — updated daily

Which Similar Diagnostics & Research Stocks Should You Also Analyze?

11 related Diagnostics & Research stocks with 13-model coverage

RVTYRevvity, Inc.QOC 7.4TWSTTwist Bioscience CorporationQOC 7.4NTRANatera, Inc.QOC 7.5CDNACareDx, Inc.QOC 7.3LDDDLongduoduo Company LimitedQOC 7.5ADPTAdaptive Biotechnologies CorporationQOC 7.2WGSGeneDx Holdings Corp.QOC 6.4PRPHProPhase Labs, Inc.QOC 4.8MTDMettler-Toledo International Inc.QOC 8.7IDXXIDEXX Laboratories, Inc.QOC 9.5MEDPMedpace Holdings, Inc.QOC 9.3

Read investment analysis: RVTY · TWST · NTRA · CDNA · LDDD · ADPT · WGS · PRPH · MTD · IDXX · MEDP

Which Other Stocks Have a Similar Quality Score to CSTL?

7 companies across all industries closest to CSTL’s Quality of Company score of 7.4/10.

KDKyndryl Holdings, Inc.QOC 7.4BAThe Boeing CompanyQOC 7.4ADArray Digital Infrastructure, Inc.QOC 7.4AMXAmérica Móvil, S.A.B. de C.V.QOC 7.4BPBP p.l.c.QOC 7.4KIMKimco Realty CorporationQOC 7.4NVDANVIDIA CorporationQOC 10.0

Read investment analysis: KD · BA · AD · AMX · BP · KIM · NVDA

What Else Do Investors Ask About Castle Biosciences, Inc.’s Valuation?

What is Castle Biosciences, Inc.'s intrinsic value in 2026?

CirclFi puts Castle Biosciences, Inc. (CSTL)'s intrinsic value at $9.38 — the median of 5 independent model estimates as of 2026-08-27, ranging from $4.34 to $38.33. One component of that median, the Bayesian DCF, runs 10,000 Monte Carlo simulations with jump-diffusion and returns $4.34 on its own. The Quality of Company score is 7.4/10 across 32 fundamental signals. All models use SEC EDGAR filings updated daily. See our methodology page for how each model works.

Is CSTL overvalued or undervalued right now?

At $34.26, 1 of 5 active models suggest CSTL may be undervalued, while 4 indicate potential overvaluation. The median of all 5 fair value estimates is $9.38, 72.6% below the current price of $34.26 — a consensus view that CSTL is overvalued. The assessment depends on which methodology best fits Castle Biosciences, Inc.'s business model in Diagnostics & Research.

What does a Quality of Company score of 7.4 mean for CSTL?

Castle Biosciences, Inc.'s QOC of 7.4/10 reflects 32 fundamental signals: profitability margins, revenue growth consistency, balance sheet leverage, free cash flow generation, and capital allocation efficiency. Scores above 7 indicate strong fundamentals and disciplined management.

How many valuation models does CirclFi run on CSTL?

CirclFi analyzes CSTL with 13 institutional-grade models daily: Bayesian DCF (Monte Carlo + jump-diffusion), EPV (Greenwald zero-growth), EROIC Spread (McKinsey reinvestment), First Chicago (3-scenario), Markov DDM (regime-switching), ML-RIV (machine learning residual income), Dynamic NAV (asset-based), PWERM (option-theoretic), Regime Cross-Sectional (relative), Sentiment SOTP (hybrid), CUCE Ensemble (meta-model), FTNN Topology (neural network), and RCMH-DCF (conditional regime). Currently 5 of 13 are active for this stock. Read the full methodology →

Which valuation models are most bullish and most bearish on CSTL?

Of the 5 models currently active on CSTL, FTNN Topology is the most bullish at $38.33 per share, and Bayesian DCF is the most bearish at $4.34. CirclFi's published fair value for CSTL is the median of that range, $9.38, not either extreme. The gap between the two ends equals 362% of the median — a wide spread, meaning the methods genuinely disagree and the median should carry less weight. Browse stocks by value-trap risk →

Is CSTL a value trap in 2026?

Castle Biosciences, Inc.'s Value Trap score is 6/100 (SAFE). This low score indicates the current valuation is not artificially depressed by fundamental deterioration, suggesting genuine opportunity rather than a trap.

Cite this analysis — “According to CirclFi’s 5-model valuation engine, Castle Biosciences, Inc. (CSTL) has a median fair value of $9.38 — 72.6% below the current price of $34.26 — as of 2026-08-27.” Source: circlfi.com/stock/CSTL/ · Methodology
Primary sources for this CSTL valuation
  • Financial statements: Castle Biosciences, Inc. 10-K and 10-Q filings on SEC EDGAR (CIK 0001447362) — 700+ standardized XBRL tags, published by the U.S. Securities and Exchange Commission.
  • Discount-rate inputs: FRED, Federal Reserve Bank of St. Louis — risk-free rates, VIX, yield curve, inflation.
  • News sentiment: The GDELT Project — global media tone, input to the Sentiment SOTP model.
  • Model definitions: CirclFi methodology — the published specification for all 13 models, including the academic sources each one implements.

Market data for CSTL as of ; valuations recomputed .

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