Castle Biosciences (CSTL) COO logs large RSU award and tax-related share dispositions

Rhea-AI Filing Summary

Castle Biosciences Chief Operating Officer Kristen M. Oelschlager reported several equity compensation transactions involving restricted stock units (RSUs) and common stock. On March 3, 2026, she received a grant of 48,367 RSUs, which vest in four equal annual installments beginning on March 3, 2027.

On March 4, 2026, she exercised or converted RSUs covering 13,811 and 11,960 RSUs at a price of $0.00 per unit, resulting in 25,771 shares of common stock acquired through derivative exercises. The filing also reports dispositions of 6,792 and 2,427 shares of common stock at $28.17 and $27.57 per share, respectively, to satisfy tax withholding obligations in connection with vested performance stock units.

Following these transactions, she holds common stock directly and also has an indirect holding of 97,251 shares of common stock through The Fritz Shorter Trust, of which she and her spouse are trustees and beneficiaries. Each RSU represents the right to receive one share of Castle Biosciences common stock.

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

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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^*

Oelschlager Kristen M

(Last) (First) (Middle)

C/O CASTLE BIOSCIENCES, INC.

1500 W. PARKWOOD AVE SUITE 400

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Operating Officer

3. Date of Earliest Transaction (Month/Day/Year)
03/03/2026

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	03/03/2026		F		2,427(1)	D	$27.57	20,068(2)	D
Common Stock	03/04/2026		M		25,771	A	(3)	45,839	D
Common Stock	03/04/2026		F		6,792	D	$28.17	39,047	D
Common Stock								97,251	I	The Fritz Shorter Trust(4)

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
Restricted Stock Units	(3)	03/03/2026		A		48,367		(5)	(5)	Common Stock	48,367	$0	48,367	D
Restricted Stock Units	(3)	03/04/2026		M			13,811	(6)	(6)	Common Stock	13,811	$0	27,621	D
Restricted Stock Units	(3)	03/04/2026		M			11,960	(7)	(7)	Common Stock	11,960	$0	35,878	D

Explanation of Responses:

1. 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.

2. Includes 965 shares acquired on February 27, 2026, under the Issuer's employee stock purchase plan.

3. Each Restricted Stock Unit ("RSU") represents the right to receive one share of the Issuer's Common Stock.

4. Held by the Fritz Shorter Trust of which the Reporting Person and her spouse are the trustees and beneficiaries.

5. The RSU's vest in four equal annual installments beginning on March 03, 2027.

6. On March 4, 2024, the Reporting Person was granted 55,243 RSUs which vest in four equal installments beginning on March 4, 2025.

7. On March 4, 2025, the Reporting Person was granted 47,838 RSUs which vest in four equal installments beginning on March 4, 2026.

Remarks:

	/s/ Frank Stokes, Attorney-in-fact	03/05/2025
	** Signature of Reporting Person	Date
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