Castle Biosciences (CSTL) director exercises options and sells shares

Rhea-AI Filing Summary

Castle Biosciences director Cole G Bradley reported option exercises and stock sales. On March 5, 2026, Bradley exercised stock options for 4,748 shares and received an equal number of common shares. He then sold a total of 7,403 common shares in open-market transactions and held 19,309 shares directly afterward.

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^*

Cole G Bradley

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
03/05/2026

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	03/05/2026		M		4,748	A	$3.38	26,712	D
Common Stock	03/05/2026		S		4,748	D	$28.44(1)	21,964	D
Common Stock	03/05/2026		S		2,655	D	$28.51(2)	19,309	D

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
Stock option (right to buy)	$3.38	03/05/2026		M			4,748	(3)	03/11/2029	Common Stock	4,748	$0	20,000	D

Explanation of Responses:

1. This transaction was executed in multiple trades at prices ranging from $28.39 to $28.51, 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.

2. This transaction was executed in multiple trades at prices ranging from $28.47 to $28.57, 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. The shares subject to the option are fully vested.

Remarks:

	/s/ Frank Stokes, Attorney-in-fact	03/09/2026
	** 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 transactions did Castle Biosciences (CSTL) director Cole G Bradley report?

Cole G Bradley reported exercising stock options for 4,748 shares and selling 7,403 Castle Biosciences common shares. These transactions occurred on March 5, 2026, and were reported as direct holdings, reflecting both a derivative exercise and subsequent open-market sales.

How many Castle Biosciences (CSTL) shares did Cole G Bradley sell in this Form 4?

Cole G Bradley sold a total of 7,403 Castle Biosciences common shares. The sales were split into 4,748 shares at a weighted-average price of about $28.44 and 2,655 shares at about $28.51, both executed as open-market or private transactions.

How many Castle Biosciences (CSTL) shares does Cole G Bradley hold after these transactions?

After the reported transactions, Cole G Bradley directly holds 19,309 Castle Biosciences common shares. This figure reflects the effect of exercising 4,748 stock options into common stock and then selling 7,403 common shares in open-market sales on March 5, 2026.

What stock option activity did Cole G Bradley report for Castle Biosciences (CSTL)?

Cole G Bradley exercised a stock option covering 4,748 Castle Biosciences shares, described as a fully vested option. The derivative transaction was reported with a price per share of $0.00 for the option, resulting in acquisition of 4,748 common shares on March 5, 2026.

Were Cole G Bradley’s Castle Biosciences (CSTL) share sales executed in multiple trades?

Yes. The reported Castle Biosciences share sales were executed in multiple trades within narrow price ranges. One group ranged from $28.39 to $28.51, and another from $28.47 to $28.57, with the Form 4 showing weighted-average sale prices for each transaction block.