[Form 4] Castle Biosciences, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Frank Stokes, Chief Financial Officer of Castle Biosciences (CSTL), reported both an issuance and a sale of company stock on 08/08/2025. He received 9,744 shares through the settlement of performance-based stock units (PSUs) at no cash cost; those PSUs are described as the remaining 50% of PSUs granted on December 23, 2022 that vested in full on the one-year anniversary of August 9, 2024. The filing also discloses a sale of 4,356 shares at $19.36 per share.

The filing lists beneficial ownership amounts of 53,072 shares following the acquisition and 48,716 shares following the sale. Based on the reported numbers, Stokes' holdings increased by 5,388 shares net (9,744 acquired minus 4,356 sold). The transactions are reported on a Form 4 filed by the reporting officer.

Positive

• 9,744 PSUs settled into shares at no cash cost, increasing the executive's equity stake
• Net increase of 5,388 shares in beneficial ownership based on the reported numbers

Negative

• Sale of 4,356 shares at $19.36, which reduced holdings after the PSU settlement
• Complexity in reported post-transaction totals (two different beneficial ownership figures shown) that may require careful reading

Insights

Financial Analyst

TL;DR: Net insider increase of 5,388 shares due to PSU settlement offset by a smaller cash sale; neutral signal overall.

The filing shows a compensation-driven issuance of 9,744 shares via settled PSUs and a concurrent cash sale of 4,356 shares at $19.36. The net result is a +5,388 share increase in beneficial ownership based on the reported post-transaction totals of 53,072 and 48,716 shares. Because the larger movement was the zero-cost PSU settlement, the activity reads as routine executive compensation realization rather than a clear directional trade.

Corporate Governance Expert

TL;DR: Routine equity-compensation vesting with a partial sale; disclosure appears complete and consistent with Form 4 requirements.

The document identifies Stokes as an officer (Chief Financial Officer) and reports both the vesting/settlement of PSUs and a contemporaneous sale. The PSU explanation explicitly ties the 9,744 units to a December 23, 2022 grant that vested as described. The presence of both acquisition (code M) and disposition (code F) entries on the Form 4 is typical for settled awards followed by partial sell-downs to cover taxes or diversify holdings; the filing provides the post-transaction beneficial ownership figures for transparency.

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

OMB Number:			3235-0287
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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^*

Stokes Frank

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
08/08/2025

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	08/08/2025		M		9,744	A	$0	53,072	D
Common Stock	08/08/2025		F		4,356	D	$19.36	48,716	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
Performance-Based Stock Unit	(1)	08/08/2025		M			9,744	(1)	(1)	Common Stock	9,744	$0	0	D

Explanation of Responses:

1. Each Performance-Based Stock Unit ("PSU") represents the right to receive one share of the Issuer's Common Stock. These PSUs represent the remaining 50% of the PSUs granted on December 23, 2022, which were all subject to time-based vesting and vested in full on the one-year anniversary of August 9, 2024.

Remarks:

	/s/ Frank Stokes, Attorney-in-fact	08/12/2025
	** 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 transactions did Frank Stokes report on Form 4 for CSTL?

He reported receiving 9,744 shares through PSU settlement and selling 4,356 shares at $19.36 on 08/08/2025.

How many PSUs vested and where did they originate?

The filing states 9,744 PSUs were the remaining 50% of a grant made on December 23, 2022 and that they vested in full on the one-year anniversary of August 9, 2024.

What were the reported beneficial ownership amounts after the transactions?

The Form 4 lists beneficial ownership of 53,072 shares following the acquisition and 48,716 shares following the sale.

What role does Frank Stokes hold at Castle Biosciences?

He is reported on the Form 4 as an officer with the title Chief Financial Officer.

What transaction codes are shown on the Form 4?

The Form 4 shows transaction code M for the acquisition (PSU settlement) and code F for the disposition (sale) as listed in the tables.