Castle Biosciences (NASDAQ: CSTL) CEO gains 62,219 shares from PSU vesting

Rhea-AI Filing Summary

Castle Biosciences reported that President and CEO Derek J. Maetzold received equity awards tied to performance. On January 12, 2026, 62,219 performance-based stock units (PSUs) granted on March 4, 2024 vested after the board certified that specific performance criteria were met. Each PSU converts into one share of common stock, so Maetzold acquired 62,219 shares of common stock at $0 per share, bringing his directly held common stock to 91,732 shares.

The filing also lists additional common stock held indirectly through various family and grantor retained annuity trusts for estate and family planning purposes. A remaining block of 62,219 PSUs from the 2024 grant is still outstanding and will vest only if stated milestones are achieved.

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

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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)
01/12/2026

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	01/12/2026		A		62,219(1)	A	$0	91,732	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(8)
Common Stock								18,718	I	By DJM Grantor Retained Annuity Trust No. 6(9)
Common Stock								44,323	I	By DJM Grantor Retained Annuity Trust No. 7(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)	01/12/2026		A		62,219		(11)	(11)	Common Stock	62,219	$0	62,219	D

Explanation of Responses:

1. Represents 50% of the Performance-Based Stock Units ("PSUs") granted on March 4, 2024 ("2024 PSUs") that vested based on the satisfaction of certain performance criteria as certified by the board of directors of the Issuer on January 12, 2026.

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 PSU represents the right to receive one share of the Issuer's Common Stock. These PSUs represent the remaining 50% of the 2024 PSUs which will vest subject to the achievement of certain milestones.

	/s/ Frank Stokes, Attorney-in-Fact	01/14/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

What insider transaction did CSTL report for Derek Maetzold?

Castle Biosciences reported that President and CEO Derek J. Maetzold had 62,219 performance-based stock units vest on January 12, 2026, resulting in the acquisition of 62,219 shares of common stock at $0 per share.

What are the 2024 performance-based stock units mentioned for CSTL?

The filing describes 2024 PSUs granted on March 4, 2024. Half of these PSUs, totaling 62,219 units, vested after performance criteria were certified as satisfied, and each unit delivered one share of common stock.

How many CSTL common shares does Derek Maetzold hold directly after this transaction?

Following the vesting and share issuance, Derek Maetzold directly beneficially owns 91,732 shares of Castle Biosciences common stock.

How many performance-based stock units remain unvested for the CSTL CEO?

The filing states that the reported PSUs represent 50% of the 2024 PSUs. The remaining 50%, equal to 62,219 PSUs, will vest only upon achievement of specified milestones.

Are there CSTL shares held indirectly through trusts related to Derek Maetzold?

Yes. The report lists indirect ownership of CSTL common stock through several trusts, including The Maetzold Descendants 2020 Trust, the Derek Maetzold 2020 Irrevocable Trust, multiple 2018 remainder trusts for family members, and DJM Grantor Retained Annuity Trusts No. 5, 6, and 7.

Does this CSTL Form 4 reflect any insider stock sales?

No sales are reported. The transactions described are acquisitions at $0 per share resulting from the vesting of performance-based stock units and updated beneficial ownership positions.