Castle Biosciences, Inc. (CSTL) Stock Analysis

Why this analysis is different

• A sector-relative MoonshotScore — five pillars (business quality, financial safety, valuation, growth durability, momentum) re-ranked nightly against the full universe of US-listed common stocks.
• An AI Council read across up to eight perspectives — value, macro, quantitative, and momentum lenses — that shows where they disagree instead of averaging the tension away.
• Figures come straight from FMP and Yahoo Finance filings data. The AI writes the narrative around the numbers — it never edits the numbers.

Castle Biosciences, Inc. (CSTL) Healthcare & Pipeline Overview

Castle Biosciences, Inc. stands out in the healthcare diagnostics sector with its proprietary multi-gene expression profile tests that enhance the management of dermatological cancers, positioning itself as a leader in personalized medicine.

What Is the Investment Thesis for CSTL?

Castle Biosciences, Inc. operates in a growing market for cancer diagnostics, with a focus on dermatological cancers that are increasingly prevalent. The company’s lead product, DecisionDx-Melanoma, is expected to drive significant revenue growth as awareness and adoption of personalized medicine increase among healthcare providers. With a market cap of $987M and a gross margin of 77.1%, the company demonstrates strong profitability potential despite its current negative profit margin of -3.8%. Key growth catalysts include the expansion of its product offerings and increasing demand for its tests, particularly as the incidence of skin cancers rises. Additionally, the company is well-positioned to capitalize on the trend towards personalized medicine, which is projected to grow at a CAGR of 11.5% through 2027. However, investors should be aware of potential risks, including regulatory challenges and competition from other diagnostic firms.

Based on FMP financials and quantitative analysis

CSTL Key Highlights

Market cap of $987M indicates a solid market presence in the diagnostics sector.

• Gross margin of 77.1% reflects strong operational efficiency compared to industry averages.
• Negative profit margin of -3.8% highlights current investment in growth over immediate profitability.
• Beta of 1.19 suggests higher volatility relative to the market, indicating potential investment risk.
• No dividend yield as the company reinvests profits into research and development.

Who Are CSTL's Competitors?

CSTL is benchmarked below against 8 industry peers on price, market cap, and our AI MoonshotScore.

AI Score by Stock Expert AI · Price data: FMP / Yahoo Finance This table mixes two scoring engines — compare a number only with others carrying the same tag.

What Are CSTL's Key Strengths?

Innovative proprietary tests that provide personalized cancer risk assessments.

• Strong gross margins indicating effective cost management.
• Established market presence in the growing dermatological cancer diagnostics sector.
• Experienced management team with a focus on research and development.

What Are CSTL's Weaknesses?

Negative profit margin indicating current investment phase rather than profitability.

• Limited product range focused primarily on dermatological cancers.
• Dependence on a small number of key products for revenue generation.
• Potential regulatory hurdles in expanding test offerings.

What Could Drive CSTL Stock Higher?

CSTL catalyst: Expansion of product offerings with new tests expected to launch in the next 12-18 months.

• Increasing adoption of DecisionDx-Melanoma as awareness of personalized medicine grows.
• Strategic partnerships with healthcare providers enhancing market reach and test utilization.
• Anticipated regulatory approvals for new diagnostic tests that could broaden the product portfolio.
• Rising incidence of skin cancer driving demand for effective diagnostic solutions.

What Are the Key Risks for CSTL?

Negative return on equity (-2.8%) — the business is not currently generating profit on shareholder capital.

• Weak fundamentals — a Piotroski F-Score of 3/9 flags soft profitability, leverage or efficiency.
• Insider selling — insiders were net sellers of roughly $6.8M recently.
• Regulatory challenges that may delay the approval of new diagnostic tests.
• Competitive pressures from established diagnostic firms and emerging technologies.
• Economic downturns that could reduce healthcare spending and impact test adoption.
• Dependence on a limited number of key products for revenue generation.

What Are the Growth Opportunities for CSTL?

• Expansion of Test Offerings: Castle Biosciences plans to broaden its portfolio of diagnostic tests, potentially increasing its addressable market. The global market for cancer diagnostics is projected to grow to $20.5 billion by 2027, with significant opportunities in personalized medicine.
• Rising Incidence of Skin Cancer: With the increasing prevalence of skin cancers, particularly melanoma, there is a growing demand for effective diagnostic tools. The American Cancer Society estimates that over 100,000 new melanoma cases will be diagnosed in the U.S. in 2026, providing a substantial market opportunity for Castle's products.
• Partnerships with Healthcare Providers: Strengthening relationships with healthcare providers can enhance test adoption rates. By collaborating with dermatology clinics and cancer treatment centers, Castle can increase its market penetration and drive revenue growth.
• Technological Advancements: Continued investment in research and development can lead to the introduction of more advanced diagnostic solutions. Innovations in genetic testing and artificial intelligence could further enhance the accuracy and efficiency of Castle's existing tests.
• International Market Expansion: Entering international markets presents a significant growth opportunity. As global awareness of skin cancer increases, Castle can leverage its proprietary tests in new regions, potentially tapping into a multi-billion dollar market.

What Are CSTL's Competitive Advantages?

• Proprietary multi-gene expression profile tests that are unique to Castle.
• Strong brand recognition in the dermatological diagnostics market.
• Established relationships with healthcare providers enhancing customer loyalty.
• High gross margins indicating operational efficiency and scalability.
• Focus on personalized medicine aligns with industry trends towards tailored treatments.

What Does CSTL Do?

Castle Biosciences, Inc. was founded in 2007 and is headquartered in Friendswood, Texas. The company has established itself as a commercial-stage diagnostics firm focused on providing innovative diagnostic and prognostic testing services specifically for dermatological cancers. Its flagship product, DecisionDx-Melanoma, is a multi-gene expression profile (GEP) test designed to assess the risk of metastasis in patients diagnosed with invasive cutaneous melanoma. In addition to this, Castle offers the DecisionDx-UM test for uveal melanoma, a rare eye cancer, and the DecisionDx-SCC test, which predicts the risk of squamous cell carcinoma metastasis based on individual tumor biology. The company also provides DecisionDx DiffDx-Melanoma and myPath Melanoma tests for diagnosing suspicious pigmented lesions. Castle Biosciences delivers its testing services through a network of physicians, ensuring that patients receive timely and accurate assessments of their cancer risks. With a workforce of 784 employees, Castle has positioned itself as a key player in the diagnostics market, leveraging its proprietary technologies to improve patient care and outcomes in dermatological oncology.

What Products and Services Does CSTL Offer?

• Develops diagnostic tests for dermatological cancers.
• Offers DecisionDx-Melanoma, a test for assessing melanoma metastasis risk.
• Provides DecisionDx-UM for predicting uveal melanoma metastasis.
• Delivers DecisionDx-SCC to evaluate squamous cell carcinoma risk.
• Markets DecisionDx DiffDx-Melanoma and myPath Melanoma for diagnosing suspicious lesions.
• Collaborates with healthcare providers to deliver testing services to patients.

How Does CSTL Make Money?

• Generates revenue through the sale of proprietary diagnostic tests.
• Operates on a fee-for-service model, billing healthcare providers for tests performed.
• Focuses on expanding its product offerings to capture a larger market share.
• Invests in research and development to innovate and enhance existing tests.
• Utilizes partnerships with healthcare providers to drive test adoption.

What Industry Does CSTL Operate In?

The medical diagnostics industry is experiencing robust growth, driven by increasing demand for early detection and personalized treatment options in oncology. The global cancer diagnostics market is projected to reach $20.5 billion by 2027, growing at a CAGR of 10.5%. Castle Biosciences, Inc. is well-positioned within this landscape, particularly in dermatological cancer diagnostics, which is becoming increasingly vital as skin cancer rates rise. The competitive landscape includes established players and emerging firms, but Castle's proprietary tests provide a unique value proposition that differentiates it from competitors.

Who Are CSTL's Key Customers?

• Healthcare providers, including dermatologists and oncologists.
• Patients diagnosed with skin cancers seeking personalized risk assessments.
• Hospitals and cancer treatment centers utilizing diagnostic testing services.
• Insurance companies that reimburse for diagnostic tests.
• Research institutions conducting studies in oncology.

Over the past six months, Castle Biosciences, Inc. insiders filed 99 SEC Form 4 transactions — 79 sales and 20 purchases. On net that is roughly 145K shares disposed (about $6.8M), a signal worth weighing alongside the fundamentals.

Castle Biosciences, Inc. has beaten Wall Street's EPS estimate in 6 of its last 8 reported quarters — a consistent record of delivering on expectations. Reported results have landed about 60.0% above estimates on average.

Castle Biosciences, Inc.'s Piotroski F-Score is 3/9, a 9-point checklist of profitability, leverage and efficiency — flagging fundamental weakness worth scrutiny. Its Altman Z-Score of 7.03 places it in the safe zone, indicating low near-term bankruptcy risk.

Return on equity for Castle Biosciences, Inc. stands at -2.8%, a gauge of how efficiently it converts shareholder capital into profit. Return on assets is -2.3%, showing how much profit it generates from its asset base. Its free cash flow yield is 0.6%, a gauge of the cash the business throws off relative to its market value. A current ratio of 6.75 indicates the company holds enough short-term assets to cover its near-term obligations. Its earnings yield is -1.8%, the inverse of the P/E and a quick read on earnings relative to price.

Castle Biosciences, Inc. (CSTL) Valuation Context

Valued at $987M, CSTL is classified as a small-cap stock. Analyst price targets span from $35.00 to $44.00, with a consensus of $39.00. At the current price of $32.32, that implies approximately 21% upside potential. Relative to its peer group, CSTL's quantitative score of 37/100 is roughly in line with the peer average of 40/100.

CSTL Revenue & Earnings Trend

In Q2 FY2026, CSTL generated $103.5M in top-line revenue, marking a sequential increase of 23.7%. The company recorded a net loss of $2.1M, with diluted EPS of $-0.07. Quarter-over-quarter revenue has been mixed, typical for a small-cap company operating in Healthcare. Across the four most recent quarters, CSTL averaged $-0.16 in diluted EPS.

Company Profile

Castle Biosciences, Inc. operates in the Medical - Diagnostics & Research industry within the Healthcare sector. It is headquartered in Friendswood, US. The company is led by CEO Derek J. Maetzold. CSTL has traded publicly since 2019.

CSTL Financials

CSTL Latest News

CSTL Analyst Consensus

CSTL MoonshotScore

CSTL Healthcare Stock FAQ

Disclaimer: This content is for informational purposes only and does not constitute investment advice. Always do your own research and consult a financial advisor.

Official Resources