Castle Biosciences Inc
NASDAQ: CSTL · HEALTHCARE · DIAGNOSTICS & RESEARCH
Updated 2026-04-30
Castle Biosciences Inc (CSTL) Stock Valuation Analysis
Fair value estimate, historical valuation range, and quality signals for CSTL.
Current price exceeds what fundamentals support. Risk/reward skewed unfavorably.
CSTL historical valuation range
Where current P/E sits in CSTL's own 5Y range.
CSTL intrinsic value (DCF)
DCF-based fair value estimate vs current market price.
Intrinsic value calculated using discounted cash flow (DCF) model based on projected free cash flows, discount rate, and terminal growth assumptions. A positive margin of safety indicates the current price is below estimated fair value, providing a cushion against estimation error.
CSTL valuation signals
Quick-read green flags, caution flags, and risks based on current metrics.
P/E Ratio — History
P/S Ratio — History
Current: 2.13x
Is CSTL overvalued in 2026?
Castle Biosciences Inc (CSTL) currently trades at $24.49 per share with a market capitalization of $734,374,000.00. Based on our multi-factor framework, the stock appears richly valued with a Smart Value Score of 31/100. This score blends growth quality, financial health, and price attractiveness into a single institutional-grade read.
CSTL currently has no meaningful P/E ratio, which typically signals that the company is unprofitable, near breakeven, or emerging from a loss-making period. With a P/S ratio of 2.1x, the market is valuing the company primarily on its revenue rather than its earnings.
Our discounted cash flow model estimates CSTL's intrinsic value at $96.60 per share, against the current market price of $24.49. This implies a margin of safety of +66.52%. A meaningful cushion exists against model error, making this a reasonable risk-adjusted entry.
Financial quality is a concern. The Piotroski F-Score of 2/9 flags weakening fundamentals that deserve closer scrutiny before the valuation case can be fully trusted.
Bottom line: CSTL appears richly valued on our framework, with a Smart Value Score of 31/100. At current levels the risk/reward is skewed against the buyer. A materially lower price or significant operational improvement would be needed to change the picture.
Frequently asked questions
Is CSTL overvalued in 2026?
Based on a Smart Value Score of 31/100, CSTL appears overvalued. Current price exceeds what fundamentals currently justify.
What is CSTL's fair value?
Our DCF model estimates CSTL's intrinsic value at $96.60 per share, versus the current price of $24.49. This produces a margin of safety of +66.52%.
What P/E ratio does CSTL trade at?
CSTL does not have a meaningful P/E ratio at this time, typically a sign of unprofitability or an ongoing earnings transition.
Is CSTL a buy based on valuation?
WallStSmart does not issue buy or sell recommendations. Our Smart Value Score of 31/100 reflects the combined read on growth, quality, and price. The profile skews cautious. Consider waiting for a better price or clearer operational improvement.
How does CSTL's valuation compare to its history?
Insufficient historical valuation data exists yet for a confident percentile read on CSTL.
What is CSTL's Smart Value Score?
CSTL's Smart Value Score is 31/100. The Smart Value Score is a proprietary WallStSmart metric blending growth quality, financial health, and valuation attractiveness into a single 0-100 read. Scores above 75 are rare and indicate strong multi-factor alignment.