Castle Biosciences (CSTL) CCO exercises options to add 11,210 shares

Rhea-AI Filing Summary

CASTLE BIOSCIENCES INC Chief Commercial Officer Juvenal W. Tobin exercised stock options and increased his direct common share holdings. On 2026-05-21, he exercised options for 11,210 shares of common stock at an exercise price of $3.38 per share. Following this transaction, he directly holds 98,035 shares of common stock. The exercised option, which was fully vested, now has no remaining balance.

Insider Trade Summary

11,210 shares exercised/converted

Mixed 2 txns

Insider Juvenal Tobin W

Role Chief Commercial Officer

Type	Security	Shares	Price	Value
Exercise	Stock option (right to buy)	11,210	$0.00	--
Exercise	Common Stock	11,210	$3.38	$38K

Holdings After Transaction: Stock option (right to buy) — 0 shares (Direct, null); Common Stock — 98,035 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Options exercised: 11,210 shares Exercise price: $3.38 per share Shares owned after: 98,035 shares +1 more

4 metrics

Options exercised 11,210 shares Stock option exercise on May 21, 2026

Exercise price $3.38 per share Conversion or exercise price of stock option

Shares owned after 98,035 shares Direct common stock holdings after transaction

Options remaining 0 shares Option balance for this grant after full exercise

Key Terms

stock option (right to buy), Exercise or conversion of derivative security, fully vested, derivative security

4 terms

stock option (right to buy) financial

"security_title: "Stock option (right to buy)" with underlying common stock"

Exercise or conversion of derivative security financial

"transaction_code_description: "Exercise or conversion of derivative security""

fully vested financial

"footnote: "The shares subject to the option are fully vested.""

derivative security financial

"transaction_action: "derivative exercise/conversion" for option position"

A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.

Form 4 Insider Transactions: What Each Field Means →

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
Estimated average burden
hours per response:			0.5

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 TEXAS 77546

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/21/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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	05/21/2026		M		11,210	A	$3.38	98,035	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	05/21/2026		M			11,210	(1)	03/12/2029	Common Stock	11,210	$0	0	D

Explanation of Responses:

1. The shares subject to the option are fully vested.

Remarks:

	/s/ Frank Stokes, Attorney-in-fact	05/26/2026
	** 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.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did CSTL executive Juvenal Tobin report?

Juvenal W. Tobin reported exercising stock options to acquire 11,210 shares of Castle Biosciences common stock. The options were exercised at an exercise price of $3.38 per share, converting his derivative position into directly held common shares.

How many CSTL shares does Juvenal Tobin own after this Form 4?

After the reported option exercise, Juvenal W. Tobin directly owns 98,035 shares of Castle Biosciences common stock. This figure reflects his position immediately following the 11,210-share option exercise reported for May 21, 2026.

What was the exercise price of Juvenal Tobin’s Castle Biosciences options?

The exercised stock options carried a conversion or exercise price of $3.38 per share. Exercising these options allowed Tobin to acquire 11,210 Castle Biosciences common shares at that fixed price rather than the prevailing market price.

Did Juvenal Tobin sell any CSTL shares in this Form 4 filing?

No sales were reported in this Form 4. The filing only shows an option exercise coded “M,” meaning Tobin converted derivative securities into 11,210 common shares, increasing his direct equity stake without any recorded open-market sale.

What happened to the stock options after Juvenal Tobin’s exercise?

The stock option for 11,210 shares was fully exercised and is now exhausted, with zero derivative shares remaining. A footnote states the shares subject to the option were fully vested, and the derivativeSummary shows no remaining option position in this filing.