Castle Biosciences (CSTL) CCO logs RSU grant, conversions and tax share withholdings

Rhea-AI Filing Summary

Castle Biosciences Chief Commercial Officer Juvenal Tobin W reported several equity compensation transactions in early March 2026. On March 3, he received a grant of 48,367 Restricted Stock Units (RSUs), each representing one share of common stock, which will vest in four equal annual installments beginning March 3, 2027.

On March 4, previously granted RSUs were exercised into common stock, and 10,399 shares and 3,716 shares of common stock were withheld to cover tax obligations in connection with vested performance or restricted stock units. After these transactions, his directly held common stock and RSU positions increased overall.

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^*

Juvenal Tobin W

(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 Commercial 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		3,716(1)	D	$27.57	92,316	D
Common Stock	03/04/2026		M		25,771	A	(2)	118,087	D
Common Stock	03/04/2026		F		10,399	D	$28.17	107,688	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
Restricted Stock Units	(2)	03/03/2026		A		48,367		(3)	(3)	Common Stock	48,367	$0	48,367	D
Restricted Stock Units	(2)	03/04/2026		M			13,811	(4)	(4)	Common Stock	13,811	$0	27,621	D
Restricted Stock Units	(2)	03/04/2026		M			11,960	(5)	(5)	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. Each Restricted Stock Unit ("RSU") represents the right to receive one share of the Issuer's Common Stock.

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

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

5. 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	03/05/2026
	** 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) report for Juvenal Tobin W?

Castle Biosciences’ Chief Commercial Officer Juvenal Tobin W reported RSU grants, RSU conversions into common stock, and share withholdings for taxes in early March 2026. These movements reflect routine equity compensation activity rather than open-market stock purchases or sales.

How many Restricted Stock Units did the Castle Biosciences CCO receive?

On March 3, 2026, the Castle Biosciences Chief Commercial Officer received a grant of 48,367 Restricted Stock Units. Each RSU represents the right to receive one share of common stock, with vesting scheduled in four equal annual installments starting March 3, 2027.

Were any Castle Biosciences shares sold on the open market in this Form 4?

The Form 4 shows dispositions coded as “F,” meaning shares were withheld to satisfy tax obligations, not sold on the open market. These tax-withholding dispositions occurred in connection with the delivery or vesting of performance or restricted stock units previously granted to the executive.

When do the newly granted RSUs to Castle Biosciences’ CCO begin vesting?

The 48,367 RSUs granted on March 3, 2026 to Castle Biosciences’ Chief Commercial Officer vest in four equal annual installments. The first installment is scheduled to vest on March 3, 2027, with the remaining portions vesting on the same date in subsequent years.

What do the RSU exercises on March 4, 2026 represent for Castle Biosciences’ CCO?

The March 4, 2026 transactions include exercises or conversions of previously granted RSUs into common stock for the executive. Some of the resulting shares were then withheld, coded as “F,” to cover tax liabilities associated with the vesting and delivery of those stock-based awards.