X0508 4 2026-03-03 0 0001447362 CASTLE BIOSCIENCES INC CSTL 0001239501 MAETZOLD DEREK J C/O CASTLE BIOSCIENCES, INC. 1500 W. PARKWOOD AVE SUITE 400 FRIENDSWOOD TX 77546 1 1 0 0 Pres. & Chief Exec. Officer 0 Common Stock 2026-03-03 4 F 0 19043 27.57 D 64655 D Common Stock 2026-03-04 4 M 0 59097 A 123752 D Common Stock 2026-03-04 4 F 0 17931 28.17 D 105821 D Common Stock 52923 I By The Maetzold Descendants 2020 Trust Common Stock 44986 I By Derek Maetzold 2020 Irrevocable Trust Common Stock 3618 I By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk Common Stock 3615 I By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold Common Stock 3615 I By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold Common Stock 3615 I By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold Common Stock 85959 I By DJM Grantor Retained Annuity Trust No. 5 Common Stock 18718 I By DJM Grantor Retained Annuity Trust No. 6 Common Stock 44323 I By DJM Grantor Retained Annuity Trust No. 7 Restricted Stock Units 2026-03-03 4 A 0 102597 0 A Common Stock 102597 102597 D Restricted Stock Units 2026-03-04 4 M 0 31110 0 D Common Stock 31110 62218 D Restricted Stock Units 2026-03-04 4 M 0 27987 0 D Common Stock 27987 83961 D Reflects the withholding of shares of the Issuer's common stock to satisfy tax withholding obligations in connection with the delivery of vested performance stock units reported on January 12, 2026. Each Restricted Stock Unit ("RSU") represents the right to receive one share of the Issuer's Common Stock. 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. Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries. 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. 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. 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. 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. Held by DJM Grantor Retained Annuity Trust No. 5 of which the Reporting Person is the trustee and beneficiary. 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. Held by DJM Grantor Retained Annuity Trust No. 7 of which the Reporting Person is the trustee and beneficiary. The RSU's vest in four equal annual installments beginning on March 03, 2027. On March 4, 2024, the Reporting Person was granted 124,437 RSUs which vest in four equal installments beginning on March 4, 2025. On March 4, 2025, the Reporting Person was granted 111,948 RSUs which vest in four equal installments beginning on March 4, 2026. /s/ Frank Stokes, Attorney-in-fact 2025-03-05