[Form 4] Castle Biosciences, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Derek Maetzold, President & CEO and a director of Castle Biosciences (CSTL), reported the conversion of 66,991 performance-based stock units into common shares and a sale of 23,972 shares at $19.36 on 08/08/2025. After the reported sale his direct beneficial ownership is shown as 112,702 shares. The filing documents trust movements on July 11, 2025 (transfers into his direct holdings) and July 14, 2025 (transfer of 44,323 shares from his direct holdings to a grantor retained annuity trust). The PSUs converted represent the remaining 50% of a December 23, 2022 grant that vested in full on the one-year anniversary of August 9, 2024.

Positive

• 66,991 PSUs converted into common shares, increasing the reporting person\'s actual shareholdings
• Detailed trust disclosures identify trustee roles and beneficiaries, providing clarity on indirect ownership

Negative

• 23,972 shares sold at $19.36, reducing direct holdings to 112,702 shares
• 44,323 shares transferred from direct holdings to DJM Grantor Retained Annuity Trust No.7, decreasing direct ownership

Insights

Financial Analyst

TL;DR: Insider vested PSUs and sold a portion of shares; transactions appear routine and do not, by themselves, signal a material change to ownership control.

The conversion of 66,991 PSUs into common stock increases the executive's share count while a concurrent disposition of 23,972 shares at $19.36 reduced direct holdings to 112,702 shares. The filing also records intra-family and grantor trust transfers totaling tens of thousands of shares, consistent with estate planning and compensation vesting mechanics. No single item in the report explicitly indicates a change in governance or control.

Corporate Governance Expert

TL;DR: Transactions reflect routine vesting and estate/trust reorganization; disclosures identify trustee roles and beneficiaries for transparency.

The filing specifies that several trusts hold portions of the reporting person's position and names the reporting person or spouse as trustee in multiple cases, improving clarity on indirect ownership. Notably, 44,323 shares were moved from direct holdings to DJM Grantor Retained Annuity Trust No.7 and other trust transfers occurred on July 11 and July 14, 2025. These are internal ownership allocations rather than market-altering events.

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

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)
08/08/2025

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	08/08/2025		M		66,991	A	$0	136,674(1)	D
Common Stock	08/08/2025		F		23,972	D	$19.36	112,702	D
Common Stock								52,923	I	By The Maetzold Descendants 2020 Trust(2)
Common Stock								44,986	I	By Derek Maetzold 2020 Irrevocable Trust(3)
Common Stock								3,618	I	By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk(4)
Common Stock								3,615	I	By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold(5)
Common Stock								3,615	I	By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold(6)
Common Stock								3,615	I	By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold(7)
Common Stock								85,959	I	By DJM Grantor Retained Annuity Trust No. 5(1)(8)
Common Stock								18,718	I	By DJM Grantor Retained Annuity Trust No. 6(1)(9)
Common Stock								44,323	I	By DJM Grantor Retained Annuity Trust No. 7(1)(10)

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
Performance-Based Stock Unit	(11)	08/08/2025		M			66,991	(11)	(11)	Common Stock	66,991	$0	0	D

Explanation of Responses:

1. Reflects the transfers on July 11, 2025, of 36,907 shares of common stock from DJM Grantor Annuity Trust No. 5 and 7,416 shares of common stock from DJM Grantor Annuity Trust No. 6 to the Reporting Person's direct holdings, and the transfer on July 14, 2025, of 44,323 shares of common stock from the Reporting Person's direct holdings to DJM Grantor Annuity Trust No. 7.

2. 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.

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

4. 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.

5. 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.

6. 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.

7. 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.

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

9. 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.

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

11. Each Performance-Based Stock Unit ("PSU") represents the right to receive one share of the Issuer's Common Stock. These PSUs represent the remaining 50% of the PSUs granted on December 23, 2022, which were all subject to time-based vesting and vested in full on the one-year anniversary of August 9, 2024.

Remarks:

	/s/ Frank Stokes, Attorney-in-fact	08/12/2025
	** 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 transactions did Castle Biosciences (CSTL) report?

The filing reports conversion of 66,991 PSUs into common stock and a sale of 23,972 shares at $19.36 on 08/08/2025.

How many shares does Derek Maetzold directly own after these transactions?

The filing shows 112,702 shares beneficially owned directly by the reporting person following the reported transactions.

Which trusts hold Maetzold\\'s indirect holdings and how many shares do they hold?

Indirect holdings include 52,923 shares held by The Maetzold Descendants 2020 Trust and 85,959 shares held by DJM Grantor Retained Annuity Trust No.5, among others listed in the filing.

What trust transfers are disclosed in the filing?

On July 11, 2025, 36,907 shares from DJM GRAT No.5 and 7,416 shares from DJM GRAT No.6 were transferred into the reporting person\\'s direct holdings; on July 14, 2025, 44,323 shares were transferred from the reporting person\\'s direct holdings to DJM GRAT No.7.

What are the PSUs that converted into shares?

The PSUs represent the remaining 50% of awards granted on December 23, 2022; they vested in full on the one-year anniversary of August 9, 2024 and each PSU equals one share of common stock.