CSTL (Castle Biosciences) Shares Buyback Ratio %: -5.27 (As of Aug. 21, 2026)

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CSTL Castle Biosciences Inc CSTL
82 GF Score
Price $32.91
GF Value $29.69
Valuation Modestly Overvalued
! 4 Warning Signs
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What is Castle Biosciences Shares Buyback Ratio %?

Castle Biosciences CSTL +1.67% 82 Shares Buyback Ratio % is -5.27 as of Aug. 21, 2026. GuruFocus rates CSTL with a GF Score™ of 82/100 and a GF Value™ of $29.69 (Modestly Overvalued). The stock has 4 warning signs investors should review.

Shares Outstanding (EOP) are shares that have been authorized, issued, and purchased by investors and are held by them.

GuruFocus calculates shares buyback ratio using previous shares outstanding minus the current shares outstanding, and then divides by previous shares outstanding. Castle Biosciences's current shares buyback ratio was -5.27%.

Castle Biosciences Shares Buyback Ratio % Related Terms

Castle Biosciences Shares Buyback Ratio % Historical Data

* Premium members only.

The historical data trend for Castle Biosciences's Shares Buyback Ratio % 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.

Castle Biosciences Shares Buyback Ratio % Chart

Castle Biosciences Annual Data
Trend Dec17 Dec18 Dec19 Dec20 Dec21 Dec22 Dec23 Dec24 Dec25
Shares Buyback Ratio %
Get a 7-Day Free Trial Premium Member Only -2.29 -4.63 -3.23 -3.91 -4.22

Castle Biosciences Quarterly Data
Sep21 Dec21 Mar22 Jun22 Sep22 Dec22 Mar23 Jun23 Sep23 Dec23 Mar24 Jun24 Sep24 Dec24 Mar25 Jun25 Sep25 Dec25 Mar26 Jun26
Shares Buyback Ratio % Get a 7-Day Free Trial Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only -0.47 -0.62 -1.80 -2.05 -0.70
CSTL
82GF Score
Castle Biosciences Inc CSTL
Shares Buyback Ratio % is just one metric. See GF Score™, valuation, warning signs, and more.
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Castle Biosciences Shares Buyback Ratio % Calculation

Castle Biosciences's Shares Buyback Ratio for the fiscal year that ended in Dec. 2025 is calculated as

Shares Buyback Ratio=(Shares Outstanding (EOP) (A: Dec. 2024 ) - Shares Outstanding (EOP) (A: Dec. 2025 )) / Shares Outstanding (EOP) (A: Dec. 2024 )
=(28.483 - 29.686) / 28.483
=-4.22%

Castle Biosciences's Shares Buyback Ratio for the quarter that ended in Jun. 2026 is calculated as

Shares Buyback Ratio=(Shares Outstanding (EOP) (A: Mar. 2026 ) - Shares Outstanding (EOP) (A: Jun. 2026 )) / Shares Outstanding (EOP) (A: Mar. 2026 )
=(30.296 - 30.509) / 30.296
=-0.70%

* 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.

Frequently Asked Questions Learn more about Shares Buyback Ratio % →
What does a Shares Buyback Ratio % of -5.27 mean?
Castle Biosciences (CSTL) has a Shares Buyback Ratio % of -5.27 as of Aug. 21, 2026. Share buyback ratio is the percent change of a company's shares outstanding from two periods. View historical data on Castle Biosciences and its competitors.
Is Castle Biosciences' Shares Buyback Ratio % too high?
Castle Biosciences' current Shares Buyback Ratio % is -5.27. Overall, Castle Biosciences has a GF Score™ of 82/100 and is considered Modestly Overvalued, reflecting its overall financial health beyond just this single metric.
How does Castle Biosciences' Shares Buyback Ratio % compare to OPK and FLGT?
Castle Biosciences' Shares Buyback Ratio % of -5.27 can be compared against companies in the Medical Diagnostics & Research industry. See the competitive comparison table and distribution chart on this page for a detailed peer-by-peer breakdown.
What is a good Shares Buyback Ratio % for a Medical Diagnostics & Research company?
A good Shares Buyback Ratio % depends on the Medical Diagnostics & Research industry context. However, Shares 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 Shares Buyback Ratio % mean?
A high Shares Buyback Ratio % can signal that a stock is expensive relative to its fundamentals. Share buyback ratio is the percent change of a company's shares outstanding from two periods. View historical data on Castle Biosciences and its competitors. Castle Biosciences's current Shares Buyback Ratio % is -5.27. 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 Overvalued. The stock's GF Value™ is $29.69, compared to a current price of $32.91 — trading 10.8% above its estimated fair value. The current Shares Buyback Ratio % is -5.27. 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 Shares Buyback Ratio % calculated?
Shares Buyback Ratio % is calculated from a company's financial statements. For Castle Biosciences (CSTL), the current Shares Buyback Ratio % is -5.27 as of Aug. 21, 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 $32.91 is trading 10.8% above its estimated GF Value™ of $29.69. GuruFocus considers Castle Biosciences to be Modestly Overvalued.

Key valuation signals for CSTL:

  • Shares Buyback Ratio %: -5.27
  • GF Value™: $29.69 vs. price of $32.91 (10.8% above fair value)
  • GF Score™: 82/100 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.
82GF Score

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Shares Buyback Ratio % is just one metric. See GF Value™, 30-year financials, guru trades, warning signs, and more.

$32.91
Price
$29.69
GF Value