CASTLE BIOSCIENCES INC — Director's Dealing 2026

Jan 22, 2026

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: CASTLE BIOSCIENCES INC (CSTL)
CIK: 0001447362
Period of Report: 2026-01-20

Reporting Person: MAETZOLD DEREK J (Director, Pres. & Chief Exec. Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2026-01-20	Common Stock	S	4017	$40.013	Disposed	87715	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	52923	Indirect
Common Stock	44986	Indirect
Common Stock	3618	Indirect
Common Stock	3615	Indirect
Common Stock	3615	Indirect
Common Stock	3615	Indirect
Common Stock	85959	Indirect
Common Stock	18718	Indirect
Common Stock	44323	Indirect

Footnotes

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.