DEREK J. MAETZOLD - 20 Jan 2026 Form 4 Insider Report for CASTLE BIOSCIENCES INC (CSTL)

Role
Pres. & Chief Exec. Officer, Director
Signature
/s/ Frank Stokes, Attorney-in-fact
Issuer symbol
CSTL
Transactions as of
20 Jan 2026
Net transactions value
-$160,732
Form type
4
Filing time
22 Jan 2026, 16:15:22 UTC
Previous filing
14 Jan 2026
Next filing
05 Feb 2026
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
MAETZOLD DEREK J Pres. & Chief Exec. Officer, Director C/O CASTLE BIOSCIENCES, INC., 1500 W. PARKWOOD AVE SUITE 401, FRIENDSWOOD /s/ Frank Stokes, Attorney-in-fact 22 Jan 2026 0001239501

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction CSTL Common Stock Sale $160,732 -4,017 -4.4% $40.01 87,715 20 Jan 2026 Direct F1, F2
holding CSTL Common Stock 52,923 20 Jan 2026 By The Maetzold Descendants 2020 Trust F3
holding CSTL Common Stock 44,986 20 Jan 2026 By Derek Maetzold 2020 Irrevocable Trust F4
holding CSTL Common Stock 3,618 20 Jan 2026 By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk F5
holding CSTL Common Stock 3,615 20 Jan 2026 By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold F6
holding CSTL Common Stock 3,615 20 Jan 2026 By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold F7
holding CSTL Common Stock 3,615 20 Jan 2026 By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold F8
holding CSTL Common Stock 85,959 20 Jan 2026 By DJM Grantor Retained Annuity Trust No. 5 F9
holding CSTL Common Stock 18,718 20 Jan 2026 By DJM Grantor Retained Annuity Trust No. 6 F10
holding CSTL Common Stock 44,323 20 Jan 2026 By DJM Grantor Retained Annuity Trust No. 7 F11
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Buy Plan / Sale Plan: These are also open market purchases/sales of shares, but in this case the transaction is part of a trading plan. Rule 10b5-1 allows insiders to setup a trading plan to buy/sell stocks over a certain period of time. Since the purchases/sales are predetermined, this protects the insiders from violating insider trading law.

Transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

Explanation of Responses:

Id Content
F1 These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on May 8, 2025.
F2 This transaction was executed in multiple trades at prices ranging from $39.695 to 40.250, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
F3 Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.
F4 Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.
F5 Held by The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk of which the Reporting Person is the trustee and his child is the beneficiary.
F6 Held by The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.
F7 Held by The Maetzold 2018 Remainder Trust FBO John Derek Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.
F8 Held by The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.
F9 Held by DJM Grantor Retained Annuity Trust No. 5 of which the Reporting Person is the trustee and beneficiary.
F10 Held by DJM Grantor Retained Annuity Trust No. 6 of which the Reporting Person is the trustee and the beneficiaries are The Maetzold 2018 Remainder Trust FBO John Derek Maetzold, The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk, The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold and The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold.
F11 Held by DJM Grantor Retained Annuity Trust No. 7 of which the Reporting Person is the trustee and beneficiary.