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Castle BiosciencesCSTL -2.63%82 3-Year Share Buyback Ratio is -3.80 as of Jun. 2026. GuruFocus rates CSTL with a GF Score™ of 82/100 and a GF Value™ of $29.72 (Fairly Valued). The stock has 4 warning signs investors should review. Among 172 Medical Diagnostics & Research companies, Castle Biosciences ranks worse than 54.65% on this metric.
Shares Outstanding (EOP) are shares that have been authorized, issued, and purchased by investors and are held by them.
3-Year Share Buyback Ratio measures the average annual proportion of a company's outstanding shares repurchased over the past three years. It is calculated as the annualized percentage change in shares outstanding from three years ago to the current year. A positive ratio may indicate share buybacks over the period, while a zero or negative ratio may reflect no repurchases or potential share issuance. Castle Biosciences's current 3-Year Share Buyback Ratio was -3.80%.
The historical rank and industry rank for Castle Biosciences's 3-Year Share Buyback Ratio or its related term are showing as below:
CSTL'
s 3-Year Share Buyback Ratio Range Over the Past 10 Years
Min: -18 Med: -9.8 Max: -3.4
Current: -3.8
During the past 9 years, Castle Biosciences's highest 3-Year Share Buyback Ratio was -3.40%. The lowest was -18.00%. And the median was -9.80%.
CSTL's 3-Year Share Buyback Ratio is ranked worse than 54.65% of 172
companies
in the Medical Diagnostics & Research industry
Industry Median: -2.5
vs CSTL: -3.80
Castle Biosciences (NAS:CSTL) 3-Year Share Buyback Ratio Explanation
A negative number means the company might be issuing new shares. A positive number indicates that the company is buying back shares.
Be Aware
Investors usually like share buybacks. But as pointed by Warren Buffett, only if a company buys back shares at the prices below the stock's intrinsic value, it rewards remaining shareholders. If a company buys its overvalued stocks back, it destroys shareholder value.
Castle Biosciences 3-Year Share Buyback Ratio Related Terms
CSTL vs OPK, FLGT, MYGN: 3-Year Share Buyback Ratio Comparison
For the Diagnostics & Research subindustry, Castle Biosciences's 3-Year Share Buyback Ratio, along with its competitors' market caps and 3-Year Share Buyback Ratio 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 3-Year Share Buyback Ratio vs Medical Diagnostics & Research Industry
For the Medical Diagnostics & Research industry and Healthcare sector, Castle Biosciences's 3-Year Share Buyback Ratio distribution charts can be found below:
* The bar in red indicates where Castle Biosciences's 3-Year Share Buyback Ratio falls into.
Castle Biosciences 3-Year Share Buyback Ratio Calculation
This is the annualized percentage change in shares outstanding from three years ago to the current year. The annualized percentage change is calculated with expontential compound based on the latest four years of annual data on Shares Outstanding (EOP).
Please click Growth Rate Calculation Example (GuruFocus) to see how GuruFocus calculates Wal-Mart Stores Inc (WMT)'s revenue growth rate. You can apply the same method to get the average dividends per share growth rate.
What does a 3-Year Share Buyback Ratio of -3.80 mean?
Castle Biosciences (CSTL) has a 3-Year Share Buyback Ratio of -3.80 as of Jun. 2026. The 3-Year Share Buyback Ratio measures the average annual proportion of a company's outstanding shares repurchased over the past three years. It is calculated as the annualized percentage change in shares outstanding from three years ago to the current year. View historical data for Castle Biosciences and its competitors. According to the industry distribution chart, Castle Biosciences ranks #94 out of 172 companies in the Medical Diagnostics & Research industry, placing it in the top 54.7%.
Is Castle Biosciences' 3-Year Share Buyback Ratio too high?
Castle Biosciences' current 3-Year Share Buyback Ratio is -3.80. Based on the distribution chart, Castle Biosciences ranks #94 out of 172 companies in the Medical Diagnostics & Research industry, which is below the industry midpoint. Overall, Castle Biosciences has a GF Score™ of 82/100 and is considered Fairly Valued, reflecting its overall financial health beyond just this single metric.
How does Castle Biosciences' 3-Year Share Buyback Ratio compare to OPK and FLGT?
According to the Medical Diagnostics & Research industry distribution chart, Castle Biosciences ranks #94 out of 172 companies for 3-Year Share Buyback Ratio. This places Castle Biosciences in the lower 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 3-Year Share Buyback Ratio for a Medical Diagnostics & Research company?
A good 3-Year Share Buyback Ratio depends on the Medical Diagnostics & Research industry context. However, 3-Year Share Buyback Ratio 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 3-Year Share Buyback Ratio mean?
A high 3-Year Share Buyback Ratio can signal that a stock is expensive relative to its fundamentals. The 3-Year Share Buyback Ratio measures the average annual proportion of a company's outstanding shares repurchased over the past three years. It is calculated as the annualized percentage change in shares outstanding from three years ago to the current year. View historical data for Castle Biosciences and its competitors. Castle Biosciences's current 3-Year Share Buyback Ratio is -3.80. 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 Fairly Valued. The stock's GF Value™ is $29.72, compared to a current price of $31.42 — trading 5.7% above its estimated fair value. The current 3-Year Share Buyback Ratio is -3.80. Castle Biosciences' overall GF Score™ is 82/100 with 4 warning signs to review. Investors should evaluate multiple metrics — including profitability, growth, and financial strength — before making a decision.
How is 3-Year Share Buyback Ratio calculated?
3-Year Share Buyback Ratio is calculated from a company's financial statements. For Castle Biosciences (CSTL), the current 3-Year Share Buyback Ratio is -3.80 as of Jun. 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 overvalued.
The current stock price of $31.42 is trading 5.7% above its estimated GF Value™ of $29.72.
GuruFocus considers Castle Biosciences to be Fairly Valued.
Key valuation signals for CSTL:
3-Year Share Buyback Ratio: -3.80
GF Value™: $29.72 vs. price of $31.42 (5.7% above 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.
82GF Score
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