Castle Biosciences, Inc. (CSTL)

In the past six months, Castle Biosciences, Inc.'s stock price has been influenced by several events. Strong third-quarter 2025 results and increased revenue guidance were reported in November 2025. Preliminary total revenue for 2025 was expected to exceed $340 million in January 2026. A strong fourth-quarter 2025 earnings beat led to a stock gain in February 2026. The stock experienced headwinds from a broader healthcare sector sell-off and macroeconomic pressures in March-April 2026. Insider selling by CEO Derek Maetzold contributed to a modest headline overhang in March-April 2026. New SEER-linked data presented at the AAD 2026 conference showed that DecisionDx-Melanoma significantly stratifies five-year melanoma-specific survival.

The demand for Castle Biosciences, Inc.'s melanoma tests exhibits predictable seasonality, with flattish sequential growth each quarter except Q1 to Q2. This seasonality is influenced by physician-patient encounters, with large dermatology meetings in the first quarter reducing physician availability and impacting test volumes.

Castle Biosciences, Inc. is a molecular diagnostics company specializing in prognostic and diagnostic tests for dermatologic cancers, Barrett's esophagus, and uveal melanoma. The company provides personalized genomic information to guide patient care. Key products include DecisionDx®-Melanoma, a gene expression profile test for melanoma risk prediction; TissueCypher® Barrett's Esophagus, a spatialomics test for esophageal cancer risk in Barrett's esophagus patients; AdvanceAD-Tx™, a GEP test for atopic dermatitis treatment selection; DecisionDx®-SCC, a GEP test for cutaneous squamous cell carcinoma metastasis risk; MyPath® Melanoma, a diagnostic GEP test for melanocytic lesions; DecisionDx®-UM, a GEP test for uveal melanoma metastasis risk; and IDgenetix, a pharmacogenomic test for mental health conditions (discontinued in May 2025).

Castle Biosciences, Inc. is headquartered in Friendswood, Texas, and has laboratory operations in Phoenix, Arizona, and Pittsburgh, Pennsylvania.

Castle Biosciences, Inc. has maintained a strong brand reputation over the past year. The company was included in Newsweek's inaugural 2025 America's Greatest Companies list. Castle Biosciences was recognized as a Greater Pittsburgh Top Workplace. Derek Maetzold was named CEO of the Year by The CEO Magazine. The company was named a Houston Chronicle Top Workplace for the fifth consecutive year and received three Culture Excellence awards. An independent expert consensus endorsed DecisionDx-Melanoma as a prognostic tool. Castle Biosciences earned the 2026 USA TODAY Top Workplaces USA Award for the fifth consecutive year.

Institutional investors hold a significant portion of Castle Biosciences, Inc.'s stock, ranging from approximately 67.72% to 93.73%. Major institutional owners include BlackRock, Inc., Vanguard Group Inc., RTW Investments, LP, Principal Financial Group Inc., Portolan Capital Management, LLC, Dimensional Fund Advisors LP, Summit Partners Public Asset Management, LLC, State Street Corp., Geode Capital Management, LLC, and AIGH Capital Management LLC. Insider ownership accounts for approximately 2.59% to 3.82% of outstanding stock, with key individual insider shareholders including David S. Kabakoff, Tobin W. Juvenal, and Derek J. Maetzold.