Castle Biosciences (NASDAQ: CSTL) CCO sells $317K in stock

Rhea-AI Filing Summary

CASTLE BIOSCIENCES INC (CSTL) reported an insider transaction by Chief Commercial Officer Juvenal Tobin W. On August 25, 2026, he sold 9,050 shares of common stock in an open-market transaction at a weighted-average price of $35.04 per share, with individual trade prices ranging from $35.00 to $35.14. The sale was executed pursuant to a Rule 10b5-1 trading plan adopted on December 10, 2025. After this transaction, he held 66,914 shares of Castle Biosciences common stock directly.

Insider Trade Summary 10b5-1

Net Seller: 9,050 shares

Net Sell 1 txn

Insider Juvenal Tobin W

Role Chief Commercial Officer

Sold 9,050 shs ($317K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	9,050	$35.04	$317K

Holdings After Transaction: Common Stock — 66,914 shares (Direct)

Footnotes (2)

1. F1. This transaction was made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 10, 2025.
2. F2. This transaction was executed in multiple trades at prices ranging from $35.00 to $35.14, 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.

Key Figures

Shares sold: 9,050 shares Weighted-average sale price: $35.04 per share Sale price range: $35.00 to $35.14 per share +3 more

6 metrics

Shares sold 9,050 shares Common stock sale by Chief Commercial Officer on August 25, 2026

Weighted-average sale price $35.04 per share Open-market sale of CSTL common stock

Sale price range $35.00 to $35.14 per share Multiple trades executed within this range

Shares held after transaction 66,914 shares Direct ownership of Juvenal Tobin W after the sale

Estimated transaction value $317,112 9,050 shares multiplied by the weighted-average price of $35.04

Rule 10b5-1 plan adoption date December 10, 2025 Plan under which the August 25, 2026 sale was executed

Key Terms

Rule 10b5-1 plan, weighted-average sale price, open-market transaction, Form 4

4 terms

Rule 10b5-1 plan regulatory

"This transaction was made pursuant to a Rule 10b5-1 plan adopted"

A Rule 10b5-1 plan is a prearranged, written schedule that lets corporate insiders buy or sell company stock at set times or amounts, even if they later learn material nonpublic information. Think of it like setting an automatic thermostat for trades: it creates a clear record that trades were planned in advance, reducing the risk of insider-trading accusations and helping investors trust that insider transactions are routine rather than based on secret information.

weighted-average sale price financial

"The price reported above reflects the weighted-average sale price"

open-market transaction market

"Sale in open market or private transaction"

An open-market transaction is a buy or sell of a company's shares or other securities conducted on a public exchange at the current market price, rather than through a private agreement. Investors watch these trades because they change the number of shares available and can move the price immediately—similar to how a large purchase at a busy store can raise demand and affect the checkout price—so such activity can signal market sentiment and alter ownership stakes.

Form 4 regulatory

"INSIDER FILING DATA (Form 4)"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

FAQ

What insider transaction did CSTL report for Juvenal Tobin W?

Castle Biosciences reported that Chief Commercial Officer Juvenal Tobin W sold 9,050 shares of common stock on August 25, 2026 in an open-market transaction, according to a Form 4 filing.

At what price were the CSTL shares sold in this Form 4 filing?

The 9,050 Castle Biosciences (CSTL) shares were sold at a weighted-average price of $35.04 per share, with individual trades executed between $35.00 and $35.14, as disclosed in the filing’s footnote.

How many CSTL shares does Juvenal Tobin W hold after the sale?

After the reported sale, Chief Commercial Officer Juvenal Tobin W directly holds 66,914 shares of Castle Biosciences common stock, as stated in the Form 4.

Was the CSTL insider sale made under a Rule 10b5-1 plan?

Yes. The sale by Juvenal Tobin W was made pursuant to a Rule 10b5-1 trading plan that he adopted on December 10, 2025, according to the footnote in the Form 4.

What is the total value of the CSTL shares sold in this transaction?

Based on 9,050 shares sold at a weighted-average price of $35.04 per share, the transaction value is approximately $317,112, as derived from the share count and reported average price in the Form 4.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/27/2026 - 04:38 PM Accepted by SEC EDGAR 08/27/2026 - 04:38 PM Learn about SEC filing dates

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).

X

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)
08/25/2026

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	08/25/2026		S(1)		9,050	D	$35.04(2)	66,914	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

Explanation of Responses:

1. This transaction was made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 10, 2025.

2. This transaction was executed in multiple trades at prices ranging from $35.00 to $35.14, 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.

Remarks:

	/s/ Frank Stokes, Attorney-in-fact	08/27/2026
	** 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)