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  4. [144] CASTLE BIOSCIENCES INC SEC Filing

CSTL insider Maetzold plans 40,046-share Rule 144 sale

Derek Maetzold and related trusts have filed a notice of intent to sell common stock of CSTL under Rule 144.

Filing Impact
(Neutral)
Filing Sentiment
(Neutral)
Form Type
144

Rhea-AI Filing Summary

Derek Maetzold and related trusts have filed a notice of intent to sell common stock of CSTL under Rule 144. The planned sales include 40,046 shares acquired on 05/10/2018 as compensation via stock options, to be disposed of through a compensation-related cashless exercise and same-day sale by 07/31/2026.

The disclosure also lists multiple sales of CSTL common stock during May–July 2026 by Maetzold and various family trusts, with individual transactions such as 6,214 shares for $137,290.52 on 05/07/2026 and 6,214 shares for $150,535.39 on 07/01/2026.

Positive

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Negative

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Shares from options to be sold 40,046 shares Common stock acquired as compensation stock options on 05/10/2018
Sale by Maetzold on 05/07/2026 6,214 shares for $137,290.52 Common stock sale by Derek Maetzold
Sale by Maetzold on 07/01/2026 6,214 shares for $150,535.39 Common stock sale by Derek Maetzold
Trust sale on 05/07/2026 1,357 shares for $29,981.21 Maetzold Descendants 2020 Trust sale of common stock
Trust sale on 07/01/2026 1,357 shares for $32,873.59 Maetzold Descendants 2020 Trust sale of common stock
Rule 144 regulatory
"notice of intent to sell common stock of CSTL under 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"
Remainder Trust financial
"The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold"
Irrevocable Trust financial
"Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020"
An irrevocable trust is a legal arrangement where an owner transfers assets into a separate entity managed by a trustee and gives up the power to modify or reclaim those assets. For investors it matters because putting stock or other holdings into such a trust can change who controls and benefits from the assets, affect taxes and creditor protection, and influence how easy it is to sell or value those holdings—like placing valuables in a locked safe overseen by someone else.
Descendants 2020 Trust financial
"The Maetzold Descendants 2020 Trust dtd 12/4/2020"

FAQ

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

What does the CSTL Rule 144 notice by Derek Maetzold cover?
The notice covers planned sales of CSTL common stock by Derek Maetzold and related family trusts, including 40,046 shares from stock options to be sold via cashless exercise and same-day sale by 07/31/2026.

How many CSTL shares are tied to Derek Maetzold’s stock options?
The disclosure shows 40,046 shares of CSTL common stock acquired on 05/10/2018 as compensation through stock options, designated for a cashless exercise and same-day sale under Rule 144.

Which recent CSTL stock sales by Derek Maetzold are reported?
Reported sales include, among others, 6,214 shares of CSTL common stock for $137,290.52 on 05/07/2026 and another 6,214 shares for $150,535.39 on 07/01/2026, both by Derek Maetzold personally.

Which trusts associated with CSTL insider Derek Maetzold sold shares?
Trust sellers include The Maetzold 2018 Remainder Trust (for several beneficiaries), the Derek Maetzold 2020 Irrevocable Trust, and the Maetzold Descendants 2020 Trust, each reporting multiple CSTL common stock sales between May and July 2026.

What CSTL share sales did the Maetzold Descendants 2020 Trust report?
The Maetzold Descendants 2020 Trust reported CSTL common stock sales such as 1,357 shares for $29,981.21 on 05/07/2026, 1,357 shares for $32,873.59 on 07/01/2026, and 1,357 shares for $32,714.96 on 07/27/2026.

What types of acquisition methods are disclosed for CSTL shares?
CSTL shares were acquired through gifts dated 10/29/2007 and through compensation stock options granted on 05/10/2018. The option-related shares are slated for compensation – cashless exercise / same-day sale.

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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