Castle Biosciences (CSTL) CEO Derek Maetzold sells 4,017 shares in 10b5-1 trades

Rhea-AI Filing Summary

Castle Biosciences Inc. insider activity: President, Chief Executive Officer and director Derek J. Maetzold reported open-market sales of common stock under a Rule 10b5-1 trading plan adopted on May 8, 2025. He sold 2,678 shares on January 5, 2026 at a weighted-average price of $38.09 per share and 1,339 shares on January 6, 2026 at a weighted-average price of $40.096 per share, for a total of 4,017 shares sold.

After these transactions, Maetzold directly held 29,513 shares of common stock. He also reported indirect beneficial ownership through multiple trusts, including 52,923 shares held by The Maetzold Descendants 2020 Trust, 44,986 shares held by the Derek Maetzold 2020 Irrevocable Trust, several 2018 remainder trusts each holding 3,615 or 3,618 shares, and 85,959, 18,718 and 44,323 shares held by DJM Grantor Retained Annuity Trusts Nos. 5, 6 and 7, respectively.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a 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). See Instruction 10.

1. Name and Address of Reporting Person^*

MAETZOLD DEREK J

(Last) (First) (Middle)

C/O CASTLE BIOSCIENCES, INC.

505 S. FRIENDSWOOD DRIVE, SUITE 401

(Street)

FRIENDSWOOD TX 77546

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
CASTLE BIOSCIENCES INC [ CSTL ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Pres. & Chief Exec. Officer

3. Date of Earliest Transaction (Month/Day/Year)
01/05/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	01/05/2026		S(1)		2,678	D	$38.09(2)	30,852	D
Common Stock	01/06/2026		S(1)		1,339	D	$40.096(3)	29,513	D
Common Stock								52,923	I	By The Maetzold Descendants 2020 Trust(4)
Common Stock								44,986	I	By Derek Maetzold 2020 Irrevocable Trust(5)
Common Stock								3,618	I	By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk(6)
Common Stock								3,615	I	By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold(7)
Common Stock								3,615	I	By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold(8)
Common Stock								3,615	I	By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold(9)
Common Stock								85,959	I	By DJM Grantor Retained Annuity Trust No. 5(10)
Common Stock								18,718	I	By DJM Grantor Retained Annuity Trust No. 6(11)
Common Stock								44,323	I	By DJM Grantor Retained Annuity Trust No. 7(12)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on May 8, 2025.

2. This transaction was executed in multiple trades at prices ranging from $37.970 to $38.450, 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.

3. This transaction was executed in multiple trades at prices ranging from $40.000 to $40.255, 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.

4. 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.

5. Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.

6. 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.

7. 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.

8. 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.

9. 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.

10. Held by DJM Grantor Retained Annuity Trust No. 5 of which the Reporting Person is the trustee and beneficiary.

11. 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.

12. Held by DJM Grantor Retained Annuity Trust No. 7 of which the Reporting Person is the trustee and beneficiary.

Remarks:

	/s/ Frank Stokes, Attorney-in-fact	01/07/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did CSTL's Derek Maetzold report?

Derek J. Maetzold, President, Chief Executive Officer and director of Castle Biosciences Inc. (CSTL), reported selling a total of 4,017 shares of common stock in open-market transactions on January 5 and 6, 2026.

At what prices were the CSTL shares sold by Derek Maetzold?

On January 5, 2026, 2,678 CSTL shares were sold at a weighted-average price of $38.09. On January 6, 2026, 1,339 shares were sold at a weighted-average price of $40.096.

Was Derek Maetzold's sale of CSTL stock under a Rule 10b5-1 plan?

Yes. The filing states that these transactions were made pursuant to a Rule 10b5-1 trading plan adopted by Derek Maetzold on May 8, 2025.

How many CSTL shares does Derek Maetzold hold directly after the reported sales?

Following the reported transactions, Derek Maetzold directly owned 29,513 shares of Castle Biosciences common stock.

What indirect CSTL holdings related to Derek Maetzold are disclosed?

The filing lists indirect holdings through several trusts, including 52,923 shares by The Maetzold Descendants 2020 Trust, 44,986 shares by the Derek Maetzold 2020 Irrevocable Trust, multiple 2018 remainder trusts each holding about 3,615–3,618 shares, and 85,959, 18,718 and 44,323 shares held by DJM Grantor Retained Annuity Trusts Nos. 5, 6 and 7.

Does the Form 4 say these CSTL trades were executed in multiple lots?

Yes. The filing explains that the January 5, 2026 sale was executed in multiple trades between $37.970 and $38.450, and the January 6, 2026 sale between $40.000 and $40.255, with weighted-average prices reported.