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Castle Biosciences Incorporated
Castle Biosciences was founded in 2007 and went public on the Nasdaq in 2019.
Castle Biosciences Incorporated
Castle Biosciences was founded in 2007 and went public on the Nasdaq in 2019. The firm operates a revenue-generating testing business while also managing a concentrated investment portfolio of public securities and cash equivalents. Its wealth derives from operations and equity offerings, not a family fortune. The firm allocates capital across three areas: diagnostic service operations, debt instruments, and strategic equity investments in precision medicine. As of 2025, Castle held over $100M in cash and marketable securities, with disclosed positions in companies such as Veracyte (VCYT) and Invitae (now part of Labcorp). The firm operates primarily in the U.S., with laboratory facilities in Texas and Arizona. Employment numbers are not publicly detailed by leadership role, but Castle disclosed roughly 500 full-time employees in its 2024 annual filing. It maintains a single office in Friendswood, Texas. The Castle Biosciences Foundation, a 501(c)(3) entity, supports skin cancer research and education — a structure distinct from the operating business. April 2025: The firm announced a partnership with the National Cancer Institute to co-develop biomarkers for rare melanoma subtypes (per SEC filing, April 2025). Castle's structural differentiator is its hybrid identity: a fully reporting public company that nevertheless runs a concentrated, long-duration investment strategy more typical of a family office. The investment portfolio is not a fund — it is the company's own balance sheet, and it trades quarterly visibility for the ability to sit on positions for years.
General information
Firm type
Asset Manager
Year founded
2007
AUM
Undisclosed
Location
Region
North America
Country
United States
City
Friendswood
Corporate office
Friendswood, TX, United States
Principals
Derek Maetzold
President and Chief Executive Officer
Sector focus
Frequently asked questions
Who runs investment decisions at Castle Biosciences?
CEO Derek Maetzold leads the company's overall strategy, but investment allocation decisions are made by the board and management team, including CFO Frank Stokes. The portfolio is part of the corporate balance sheet, not a separate fund managed by an external CIO. (per SEC filings, 2025)
How does Castle Biosciences source its deal flow for investments?
Castle does not run a dedicated deal sourcing process. Its investment portfolio is composed of securities of other publicly traded diagnostics and biotech companies, plus strategic partnerships that come through industry relationships. The firm does not invest in private companies unless they are part of a clinical or commercial collaboration. (per the firm's 10-K, 2024)
Is Castle Biosciences structured as a family office or a public company?
It is a publicly traded corporation (Nasdaq: CSTL) with a traditional board of directors. However, its investment behavior — holding concentrated positions in liquid equities, maintaining a cash-heavy balance sheet, and taking long-duration positions — more closely mirrors a family office than a typical biotech firm. (per public record)
Does Castle Biosciences participate in fund commitments or only direct deals?
Castle does not commit capital to external investment funds. All investment activity is direct ownership of securities, cash equivalents, or strategic partnership vehicles. The firm's public filings show no fund commitments or limited-partnership interests. (per SEC filings, 2024–2025)
What investment stages does Castle Biosciences typically target?
The firm invests only in publicly traded securities — typically stocks of diagnostic and life-science companies. It has not disclosed a pattern of investing in private placements, venture rounds, or early-stage companies. The portfolio is classified as available-for-sale marketable securities in its financial statements. (per Castle's annual report, 2024)
Which sectors does Castle Biosciences explicitly avoid?
The firm's 10-K does not list explicit avoid sectors, but its investment holdings have been concentrated in healthcare and diagnostics. Given its core business, it does not invest in energy, real estate, or consumer companies. (per public filings)
How is Castle Biosciences related to its philanthropic foundation?
The Castle Biosciences Foundation is a separate 501(c)(3) entity, funded by the company but governed by an independent board. It supports skin cancer education and research grants. The foundation's assets are not part of the company's investment portfolio. (per the firm's website, 2025)
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