CSTL Stock Summary and Trading Ideas (Castle Biosciences | NASDAQ:CSTL)

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. It also provides DecisionDx-UM, a risk stratification GEP test. The company also offers its products to the skin cancer and gastroenterology markets.

Castle Biosciences trades on the NASDAQ stock market under the symbol CSTL.

As of December 12, 2025, CSTL stock price climbed to $38.63 with 349,131 million shares trading.

CSTL has a beta of 0.51, meaning it tends to be less sensitive to market movements. CSTL has a correlation of 0.02 to the broad based SPY ETF.

CSTL has a market cap of $1.11 billion. This is considered a Small Cap stock.

Last quarter Castle Biosciences reported $83 million in Revenue and -$.02 earnings per share. This beat revenue expectation by $12 million and exceeded earnings estimates by $.42.

In the last 3 years, CSTL traded as high as $40.61 and as low as $9.26.

The top ETF exchange traded funds that CSTL belongs to (by Net Assets): IWM, VTI, IWN, VXF, IBB.

CSTL has outperformed the market in the last year with a return of +32.7%, while the SPY ETF gained +14.0%. In the last 3 month period, CSTL beat the market returning +80.3%, while SPY returned +4.0%. However, in the most recent 2 weeks CSTL has underperformed the stock market by returning -3.3%, while SPY returned -0.2%.

CSTL support price is $36.94 and resistance is $39.01 (based on 1 day standard deviation move). This means that using the most recent 20 day stock volatility and applying a one standard deviation move around the stock's closing price, stastically there is a 67% probability that CSTL shares will trade within this expected range on the day.