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  4. [144] CASTLE BIOSCIENCES INC SEC Filing

Castle Biosciences officer proposes $1.06M share sale

The proposed sales are connected to a June 2, 2026 selling plan intended to comply with Rule 10b5-1(c).

Filing Impact
(Neutral)
Filing Sentiment

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Form Type
144

Rhea-AI Filing Summary

Castle Biosciences, Inc. (CSTL) is identified as the issuer in a planned sale of 28,992 common shares for Officer Derek Maetzold’s account through Goldman Sachs & Co. LLC. The proposed sale has an aggregate market value of $1,062,556.8 and an approximate sale date of October 5, 2026.

The stated allocation is 17,160 shares by Derek Maetzold, 5,436 by DM 2020 Irrev Trust, and 6,396 by Maetzold Descendants 2020 Tr. The sales are connected to a selling plan dated June 2, 2026, intended to comply with Rule 10b5-1(c). Separate past-three-months transactions are also listed for Maetzold and named trusts.

Proposed sale 28,992 common shares Approximate sale date: October 5, 2026
Aggregate market value $1,062,556.8 Proposed sale
Shares allocated to Derek Maetzold 17,160 shares Stated allocation of shares to be sold
Shares allocated to DM 2020 Irrev Trust 5,436 shares Stated allocation of shares to be sold
Shares allocated to Maetzold Descendants 2020 Tr 6,396 shares Stated allocation of shares to be sold
Rule 10b5-1(c) regulatory
"intended to comply with Rule 10b5-1(c)"
Rule 10b5-1(c) is an SEC guideline that lets company insiders set up a written, pre-planned schedule to buy or sell their company stock when they are not in possession of material, nonpublic information. For investors, it matters because such plans can reduce the appearance of insider trading by separating decisions from inside knowledge—like putting your trades on autopilot—while also requiring scrutiny since pre-planned trades can still affect market confidence and share value.
Rule 144 regulatory
"sales required by paragraph (e) of Rule 144"
Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.
cashless exercise / same-day sale financial
"Compensation -- Cashless exercise / same-day sale"
aggregate market value financial
"aggregate market value"
Aggregate market value is the combined price you would pay to buy all outstanding shares of a company or all companies in a group at current market prices — essentially the sum of each stock’s market capitalization. It matters to investors because it shows the overall size and weight of an investment or sector (like the total cost to buy every piece of a puzzle), helps compare scale across companies or markets, and influences index composition and risk exposure.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many CSTL shares are proposed for sale?
The proposed sale covers 28,992 common shares, with an aggregate market value of $1,062,556.8 and an approximate sale date of October 5, 2026.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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144: Filer Information

144: Issuer Information

144: Securities Information



Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold


* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.



Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

144: Remarks and Signature

Source: View Original Filing on SEC EDGAR

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