144 0001239501 XXXXXXXX LIVE 0001447362 Castle Biosciences, Inc. 001-38984 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 1-866-788-9007 Derek Maetzold Officer Common Goldman Sachs & Co. LLC 200 West Street New York NY 10282 29014 938022.62 30549507 09/11/2026 NASD Common 10/29/2007 Acquired as a gift Derek Maetzold Y 10/29/2007 6405 10/29/2007 None Common 10/29/2007 Acquired as a gift Derek Maetzold Y 10/29/2007 5445 10/29/2007 None Common 05/10/2018 Acquired as compensation -- Stock Options Issuer N 17164 05/10/2018 Compensation -- Cashless exercise / same-day sale N The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 278 5726.07 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 278 5726.07 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 278 5726.07 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 278 5726.07 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 1153 23748.76 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 1357 27950.63 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 550 11328.55 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/01/2026 278 6734.6 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/01/2026 6214 150535.39 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/01/2026 1357 32873.59 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/01/2026 278 6734.6 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/01/2026 1153 27931.65 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/01/2026 278 6734.6 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/01/2026 278 6734.6 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/14/2026 1153 26359.34 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/14/2026 278 6355.5 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/14/2026 278 6355.5 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/14/2026 1357 31023.08 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/14/2026 278 6355.5 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/14/2026 550 12573.84 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/14/2026 278 6355.5 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/27/2026 278 6702.11 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/27/2026 1357 32714.96 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/27/2026 278 6702.11 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/27/2026 278 6702.11 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/27/2026 1153 27796.87 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/27/2026 278 6702.11 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/27/2026 6214 149808.98 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/31/2026 6480 194992.13 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/31/2026 1983 59671.2 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 07/31/2026 1690 50854.43 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/03/2026 4232 128198.6 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/03/2026 3597 108962.75 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/03/2026 10664 323041.08 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/04/2026 6929 215134.07 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/04/2026 8156 253230.41 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/04/2026 20356 632020.39 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/05/2026 556 17024.86 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/05/2026 473 14483.39 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/05/2026 2546 77959.2 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 157 5179.89 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 193 6367.63 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 3414 112637.76 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 676 22303.2 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 156 5146.89 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 624 20587.57 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 681 22468.16 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 692 22831.09 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 3169 104554.5 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 156 5146.89 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 3045 100463.38 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 599 19762.75 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 122 4025.13 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 554 18278.07 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 85 2804.4 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 122 4025.13 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 2800 92380.12 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 529 17453.24 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 121 3992.14 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/28/2026 665 21940.28 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 987 29521.66 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 484 14612.98 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 370 11102.89 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 873 26292.4 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 204 6101.74 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 74 2220.58 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 204 6101.74 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 74 2220.58 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 408 12203.48 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 197 5947.84 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 142 4261.11 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 353 10631.41 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 852 25483.75 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 413 12469.34 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 301 9032.35 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 740 22286.8 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 204 6101.74 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 74 2220.58 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 219 6550.4 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 08/14/2026 59 1770.46 The sales of shares set forth herein are made in connection with a selling plan dated 06/02/2026 that is intended to comply with Rule 10b5-1(c). Total number of shares to be sold includes: 17,164 shares by Derek Maetzold, 5,445 shares by DM 2020 Irrev Trust, and 6,405 shares by Maetzold Descendants 2020 Tr. 09/11/2026 06/02/2026 Goldman Sachs & Co. LLC on behalf of Derek Maetzold