Castle BiosciencesCSTL +1.02%72 FCF Margin % is -41.33% as of Mar. 2026. GuruFocus rates CSTL with a GF Score™ of 72/100 and a GF Value™ of $29.15 (Modestly Undervalued). The stock has 4 warning signs investors should review. Among 204 Medical Diagnostics & Research companies, Castle Biosciences ranks better than 54.9% on this metric.
The historical rank and industry rank for Castle Biosciences's FCF Margin % or its related term are showing as below:
CSTL'
s FCF Margin % Range Over the Past 10 Years
Min: -92.55 Med: -8.76 Max: 11.72
Current: 1.33
During the past 9 years, the highest FCF Margin % of Castle Biosciences was 11.72%. The lowest was -92.55%. And the median was -8.76%.
CSTL's FCF Margin % is ranked better than 54.9% of 204
companies
in the Medical Diagnostics & Research industry
Industry Median: -1.845
vs CSTL: 1.33
Castle Biosciences FCF Margin % Related Terms
Castle Biosciences FCF Margin % Historical Data
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The historical data trend for Castle Biosciences's FCF Margin % can be seen below:
* For Operating Data section: All numbers are indicated by the unit behind each term and all currency related amount are in USD. * For other sections: All numbers are in millions except for per share data, ratio, and percentage. All currency related amount are indicated in the company's associated stock exchange currency.
For the Diagnostics & Research subindustry, Castle Biosciences's FCF Margin %, along with its competitors' market caps and FCF Margin % data, can be viewed below:
* Competitive companies are chosen from companies within the same industry, with headquarter located in same country, with closest market capitalization; x-axis shows the market cap, and y-axis shows the term value; the bigger the dot, the larger the market cap. Note that "N/A" values will not show up in the chart.
Castle Biosciences FCF Margin % vs Medical Diagnostics & Research Industry
For the Medical Diagnostics & Research industry and Healthcare sector, Castle Biosciences's FCF Margin % distribution charts can be found below:
* The bar in red indicates where Castle Biosciences's FCF Margin % falls into.
* For Operating Data section: All numbers are indicated by the unit behind each term and all currency related amount are in USD. * For other sections: All numbers are in millions except for per share data, ratio, and percentage. All currency related amount are indicated in the company's associated stock exchange currency.
Castle Biosciences (CSTL) has a FCF Margin % of -41.33% as of Mar. 2026. Free cash flow margin is the ratio of total free cash flow to net sales. View historical data on Castle Biosciences and its competitors. According to the industry distribution chart, Castle Biosciences ranks #92 out of 204 companies in the Medical Diagnostics & Research industry, placing it in the top 45.1%.
Is Castle Biosciences' FCF Margin % too high?
Castle Biosciences' current FCF Margin % is -41.33%. Based on the distribution chart, Castle Biosciences ranks #92 out of 204 companies in the Medical Diagnostics & Research industry, which is above the industry midpoint. Overall, Castle Biosciences has a GF Score™ of 72/100 and is considered Modestly Undervalued, reflecting its overall financial health beyond just this single metric.
How does Castle Biosciences' FCF Margin % compare to FLGT and MYGN?
According to the Medical Diagnostics & Research industry distribution chart, Castle Biosciences ranks #92 out of 204 companies for FCF Margin %. This puts Castle Biosciences in the upper half of its industry. See the competitive comparison table and distribution chart on this page for a detailed peer-by-peer breakdown.
What is a good FCF Margin % for a Medical Diagnostics & Research company?
A good FCF Margin % depends on the Medical Diagnostics & Research industry context. However, FCF Margin % should not be evaluated in isolation — investors should consider it alongside profitability, growth, and financial strength metrics. Use the industry distribution chart on this page to see where any company falls relative to its peers.
What does a high FCF Margin % mean?
A high FCF Margin % can signal that a stock is expensive relative to its fundamentals. Free cash flow margin is the ratio of total free cash flow to net sales. View historical data on Castle Biosciences and its competitors. Castle Biosciences's current FCF Margin % is -41.33%. However, context matters — high-growth companies often justify higher valuations. Always evaluate alongside other metrics like GF Score™ and GF Value™.
Is Castle Biosciences stock overvalued right now?
Based on GuruFocus' analysis, Castle Biosciences (CSTL) is currently considered Modestly Undervalued. The stock's GF Value™ is $29.15, compared to a current price of $22.35 — trading 23.3% below its estimated fair value. The current FCF Margin % is -41.33%. Castle Biosciences' overall GF Score™ is 72/100 with 4 warning signs to review. Investors should evaluate multiple metrics — including profitability, growth, and financial strength — before making a decision.
How is FCF Margin % calculated?
FCF Margin % is calculated from a company's financial statements. For Castle Biosciences (CSTL), the current FCF Margin % is -41.33% as of Mar. 2026. GuruFocus calculates this using data sourced from SEC filings and annual reports. See the calculation section and 30-year financial data on this page for the full breakdown.
Is Castle Biosciences (CSTL) Overvalued in 2026?
Based on GuruFocus' analysis, Castle Biosciences stock appears to be undervalued.
The current stock price of $22.35 is trading 23.3% below its estimated GF Value™ of $29.15.
GuruFocus considers Castle Biosciences to be Modestly Undervalued.
Key valuation signals for CSTL:
FCF Margin %: -41.33%
GF Value™: $29.15 vs. price of $22.35 (23.3% below fair value)
No single metric tells the full story. See the CSTL stock analysis page for a complete view including 30-year financials, guru trades, and insider activity.
Castle Biosciences Inc is a molecular diagnostics company. The group provides test solutions for the diagnosis and treatment of dermatologic cancers, Barrett's esophagus (BE), and uveal melanoma. The product portfolio of the company includes DecisionDx-Melanoma, a risk stratification gene expression profile (GEP) test; DecisionDx-SCC, a risk stratification test for cutaneous squamous cell carcinoma; MyPath Melanoma, a diagnostic GEP test for use in patients with difficult-to-diagnose melanocytic lesions; and TissueCypher, a test to predict future development of progression of high-grade dysplasia and/or esophageal cancer. The company derives revenues through the delivery of test reports for its molecular diagnostic tests.
72GF Score
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