Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 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 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES 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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(Print or Type Responses)

1. Name and Address of Reporting Person * Stokes Frank 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 Financial Officer (Last) (First) (Middle) C/O CASTLE BIOSCIENCES, INC., 1500 W. PARKWOOD AVE SUITE 400 3. Date of Earliest Transaction (Month/Day/Year) 03/03/2026 (Street) FRIENDSWOOD, TX 77546 4. If Amendment, Date 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 (City) (State) (Zip) 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 S(1) 5,300 D $27.32(2) 54,183(3) D Common Stock 03/03/2026 S(1) 1,700 D $27.81(4) 52,483 D Common Stock 03/03/2026 F 3,611(5) D $27.57 48,872 D Common Stock 03/04/2026 M 24,146 A (6) 73,018 D Common Stock 03/04/2026 F 10,732 D $28.17 62,286 D Common Stock 03/04/2026 M 3,800 A $3.38 66,086 D

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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 Underlying Securities (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 of Derivative Security: 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

(6)

03/03/2026

A

48,367

(7)

(7)

Common Stock

48,367

$ 0

48,367

D

Restricted Stock Units

(6)

03/04/2026

M

12,186

(8)

(8)

Common Stock

12,186

$ 0

24,372

D

Restricted Stock Units

(6)

03/04/2026

M

11,960

(9)

(9)

Common Stock

11,960

$ 0

35,878

D

Stock option (right to buy)

$3.38

03/04/2026

M

3,800

(10)

03/12/2029

Common Stock

3,800

$ 0

14,912

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Stokes Frank C/O CASTLE BIOSCIENCES, INC. 1500 W. PARKWOOD AVE SUITE 400 FRIENDSWOOD, TX 77546			Chief Financial Officer

Signatures

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

Explanation of Responses:

*	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).
(1)	The transaction on this Form 4 was made pursuant to a Rule 10b5-1 plan adopted by Frank Stokes on November 13, 2025.
(2)	This transaction was executed in multiple trades at prices ranging from $26.70 to $27.67, 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)	Includes 1,033 shares acquired on February 27, 2026, under the Issuer's employee stock purchase plan.
(4)	This transaction was executed in multiple trades at prices ranging from $27.72 to $27.97, 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.
(5)	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.
(6)	Each Restricted Stock Unit ("RSU") represents the right to receive one share of the Issuer's Common Stock.
(7)	The RSU's vest in four equal annual installments beginning on March 03, 2027.
(8)	On March 4, 2024, the Reporting Person was granted 48,744 RSUs which vest in four equal installments beginning on March 4, 2025.
(9)	On March 4, 2025, the Reporting Person was granted 47,838 RSUs which vest in four equal installments beginning on March 4, 2026.
(10)	The shares subject to the option are fully vested.

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