CSTL (Castle Biosciences) Moat Score: 6/10 (As of Jun. 28, 2026)


CSTL Castle Biosciences Inc CSTL
73 GF Score
Price $24.21
GF Value $29.16
Valuation Modestly Undervalued
! 4 Warning Signs
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What is Castle Biosciences Moat Score?

Castle Biosciences CSTL +6.07% 73 Moat Score is 6 as of Jun. 28, 2026. GuruFocus rates CSTL with a GF Score™ of 73/100 and a GF Value™ of $29.16 (Modestly Undervalued). The stock has 4 warning signs investors should review. Among 216 Medical Diagnostics & Research companies, Castle Biosciences ranks better than 93.98% on this metric.

Castle Biosciences has the Moat Score of 6, which implies that the company might have Narrow Moat - Strong narrow moat, clearly distinguishable but not wide.

Castle Biosciences has Narrow Moat: Castle Biosciences Inc has a strong narrow moat due to its proprietary diagnostic tests and significant R&D capabilities. However, it faces competition and lacks strong brand strength or significant regulatory barriers.

Moat Score is a ranking system developed by GuruFocus to assess a company's ability to sustain a competitive advantage, rated on a scale from 0 to 10. It takes into account key factors such as market leadership, cost advantages, network effects, customer switching costs, and more.

The company's Moat Score is based on these criteria:

1. Market leadership and sustainable market share
2. Network effects and significant customer switching costs
3. Valuable intellectual property and patents
4. Strong brand strength and deep customer loyalty
5. Durable cost advantages (e.g., economies of scale, proprietary technology)
6. Significant regulatory barriers and exclusive licenses
7. Superior distribution network
8. Strong and sustainable pricing power
9. Consistent and impactful innovation and R&D capabilities

Based on the research, GuruFocus believes Castle Biosciences might have Narrow Moat - Strong narrow moat, clearly distinguishable but not wide.

Castle Biosciences  (NAS:CSTL) Moat Score Explanation

The Moat Score ranges from 0 to 10, with 10 as the highest. GuruFocus divided Moat Score into following 8 categories:

Moat Score Moat Level
10Wide Moat - Exceptionally dominant and durable wide moat
8 - 9Wide Moat - Clear and robust wide moat
7Wide Moat - Entry-level wide moat, clearly possessing durable advantages
6Narrow Moat - Strong narrow moat, clearly distinguishable but not wide
5Narrow Moat - Solid narrow moat
4Narrow Moat - Discernible but modest moat
1 - 3No Moat - Very weak/transient advantages
0No Moat - No discernible moat

Castle Biosciences Moat Score Related Terms

CSTL vs FLGT, MYGN, PRE: Moat Score Comparison

For the Diagnostics & Research subindustry, Castle Biosciences's Moat Score, along with its competitors' market caps and Moat Score 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 Moat Score vs Medical Diagnostics & Research Industry

For the Medical Diagnostics & Research industry and Healthcare sector, Castle Biosciences's Moat Score distribution charts can be found below:

* The bar in red indicates where Castle Biosciences's Moat Score falls into.


CSTL
73GF Score
Castle Biosciences Inc CSTL
Moat Score is just one metric. See GF Score™, valuation, warning signs, and more.
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Frequently Asked Questions Learn more about Moat Score →
What does a Moat Score of 6 mean?
Castle Biosciences (CSTL) has a Moat Score of 6 as of Jun. 28, 2026. Moat Score is a ranking system developed by GuruFocus to assess a company's ability to sustain a competitive advantage, rated on a scale from 0 to 10. It takes into account key factors such as market leadership, cost advantages, network effects, customer switching costs, and more. According to the industry distribution chart, Castle Biosciences ranks #13 out of 216 companies in the Medical Diagnostics & Research industry, placing it in the top 6%.
Is Castle Biosciences' Moat Score too high?
Castle Biosciences' current Moat Score is 6. Based on the distribution chart, Castle Biosciences ranks #13 out of 216 companies in the Medical Diagnostics & Research industry, which is in the top quartile — a strong position relative to peers. Overall, Castle Biosciences has a GF Score™ of 73/100 and is considered Modestly Undervalued, reflecting its overall financial health beyond just this single metric.
How does Castle Biosciences' Moat Score compare to FLGT and MYGN?
According to the Medical Diagnostics & Research industry distribution chart, Castle Biosciences ranks #13 out of 216 companies for Moat Score. This places Castle Biosciences in the top 6% of its industry — outperforming the majority of peers. See the competitive comparison table and distribution chart on this page for a detailed peer-by-peer breakdown.
What is a good Moat Score for a Medical Diagnostics & Research company?
A good Moat Score depends on the Medical Diagnostics & Research industry context. However, Moat Score 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 Moat Score mean?
A high Moat Score can signal that a stock is expensive relative to its fundamentals. Moat Score is a ranking system developed by GuruFocus to assess a company's ability to sustain a competitive advantage, rated on a scale from 0 to 10. It takes into account key factors such as market leadership, cost advantages, network effects, customer switching costs, and more. Castle Biosciences's current Moat Score is 6. 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 $29.16, compared to a current price of $24.21 — trading 17% below its estimated fair value. The current Moat Score is 6. Castle Biosciences' overall GF Score™ is 73/100 with 4 warning signs to review. Investors should evaluate multiple metrics — including profitability, growth, and financial strength — before making a decision.
How is Moat Score calculated?
Moat Score is calculated from a company's financial statements. For Castle Biosciences (CSTL), the current Moat Score is 6 as of Jun. 28, 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 $24.21 is trading 17% below its estimated GF Value™ of $29.16. GuruFocus considers Castle Biosciences to be Modestly Undervalued.

Key valuation signals for CSTL:

  • Moat Score: 6
  • GF Value™: $29.16 vs. price of $24.21 (17% below fair value)
  • GF Score™: 73/100 with 4 warning signs

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 Business Description

Other Exchanges 086:Germany
Address 1500 West Parkwood Avenue, Suite 401, Friendswood, TX, USA, 77546
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.
73GF Score

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$24.21
Price
$29.16
GF Value