Castle Biosciences, Inc. filings document the regulatory record for a Delaware molecular diagnostics company with common stock listed on the Nasdaq Global Market under CSTL. Recent Form 8-K filings report quarterly and annual operating results, preliminary performance updates, and Regulation FD slide presentations tied to management communications.
The company’s proxy materials cover annual meeting matters, executive compensation, director elections, stockholder voting procedures, and governance disclosures. Other material-event filings document amendments to bylaws, including provisions related to stockholder meetings, director nominations, and board governance, alongside standing disclosures on registered securities and exchange listing status.
CASTLE BIOSCIENCES INC President and CEO Derek J. Maetzold reported a series of insider trades in May 2026 involving company common stock. Across several family trusts and a personal account, entities associated with him sold a net 4,172 shares in open-market transactions at prices around $20 per share.
On the same dates, he exercised stock options to acquire 550 shares at an exercise price of $2.39 per share, increasing his direct common stock holdings. Following these transactions, one direct holding account shows 21,479 shares, while certain family trusts continue to hold tens of thousands of shares. The filing notes that these sales were executed under a pre-arranged Rule 10b5-1 trading plan adopted on December 3, 2025, indicating the trades were scheduled in advance rather than timed discretionarily.
Portolan Capital Management, LLC and manager George McCabe amended a Schedule 13G reporting beneficial ownership of 1,350,283 shares of Castle Biosciences common stock as of 03/31/2026. The filing shows 4.45% ownership and indicates sole voting and dispositive power over those shares. The amendment is signed by Mr. McCabe on 05/15/2026.
Castle Biosciences, Inc. ownership disclosure: RTW Investments, LP and Roderick Wong report beneficial ownership of 2,758,335 shares, representing 9.3% of Castle Biosciences' Common Stock based on February 19, 2026 outstanding share count of 29,731,198 shares.
The filing is an amendment to a Schedule 13G and states the reported shares are directly held by RTW Funds and that the RTW Funds have the right to receive dividends or sale proceeds. Shared voting and dispositive power are reported; sole voting and dispositive power are reported as zero.
Castle Biosciences CEO Derek J. Maetzold reported a mix of stock option exercises and share sales in Castle Biosciences Inc. common stock. On May 7, 2026, he exercised options to acquire 6,214 shares at an exercise price of $2.39 per share, converting a derivative award into common stock.
The filing also shows open-market sales totaling 9,836 shares at weighted-average prices around $22.08–$22.585 per share. These sales occurred both in his direct account and through several family and estate-planning trusts, including the Maetzold 2018 remainder trusts and 2020 trusts for descendants.
Following these transactions, Maetzold directly holds 22,385 Castle Biosciences shares, while additional shares are held indirectly through multiple trusts where he or his spouse serves as trustee. A footnote states that the transactions were carried out under a pre-arranged Rule 10b5-1 trading plan adopted on December 3, 2025, indicating the trades were scheduled in advance.
Derek Maetzold filed a Form 144 reporting proposed and recent sales of Common stock in connection with transactions routed through Goldman Sachs & Co. LLC. The filing lists multiple open-market disposals, including 23,179 shares for $584,548.88 on 03/12/2026 and 18,650 shares for $482,441.93 on 03/17/2026.
The excerpt also shows prior cashless exercises and same-day sales tied to 6,764 stock options dated 11/12/2018, and numerous trust-held share dispositions across March–April 2026.
Castle Biosciences reported Q1 2026 results with net revenues of $83.7 million, down from $88.0 million a year earlier, as its dermatologic and gastroenterology diagnostics portfolio continued to drive sales. The company’s net loss narrowed to $14.5 million from $25.8 million, reflecting lower operating expenses, including a sharp reduction in amortization of acquired intangibles.
Cash and cash equivalents were $63.8 million and marketable investment securities were $197.9 million as of March 31, 2026, supporting management’s view that current resources and expected revenues can fund operations for at least the next 12 months. Test volume grew to 26,933 reports, driven by growth in DecisionDx-Melanoma and a 58% increase in TissueCypher usage, while operating cash outflows increased as the company invested in its expanding test portfolio and new facilities.
Castle Biosciences reported first-quarter 2026 results, with revenue of $83.7 million. Revenue declined from $88.0 million a year earlier, but core tests DecisionDx-Melanoma and TissueCypher grew volumes 16% and 58%, driving a 36% combined increase.
GAAP gross margin was 73%, with non-GAAP Adjusted Gross Margin of 75.6%. The company posted a net loss of $14.5 million and Adjusted EBITDA of $(5.1) million. Cash, cash equivalents and marketable securities totaled $261.7 million.
Castle raised its 2026 total revenue guidance to $345–355 million from $340–350 million, citing momentum in core tests and expanding clinical evidence across dermatology, gastroenterology and atopic dermatitis, including new data supporting DecisionDx-Melanoma, TissueCypher and AdvanceAD-Tx.
Entities associated with Castle Biosciences CEO Derek Maetzold reported open-market sales totaling 4,172 shares of Common Stock on April 21 at a weighted-average price of $25.098 per share. These transactions were made pursuant to a Rule 10b5-1 plan adopted on December 3, 2025.
The filing also shows Maetzold exercised stock options to acquire 550 shares at $2.39 per share and sold a matching 550 shares, leaving 21,479 shares held directly, plus additional indirect holdings in several family and grantor retained annuity trusts.
CASTLE BIOSCIENCES INC President & CEO Derek J. Maetzold reported an exercise-and-sell transaction in company stock. On April 6, 2026, he exercised stock options to acquire 6,214 shares of common stock at an exercise price of $2.39 per share, converting previously granted options into shares.
On the same date, Maetzold sold 6,214 directly held shares of common stock at a weighted-average price of about $25.03 per share, along with additional open-market sales through several family and estate-planning trusts totaling 9,836 shares sold overall. According to the filing, these sales were made under a Rule 10b5-1 trading plan adopted on December 3, 2025, indicating they were pre-scheduled rather than opportunistic trades.
After these transactions, Maetzold continues to hold 21,479 shares directly and maintains substantial indirect ownership through multiple trusts, including 48,852 shares in The Maetzold Descendants 2020 Trust and 85,959 shares in DJM Grantor Retained Annuity Trust No. 5, among other vehicles.