Castle Biosciences CCO sells 6,600 shares

Castle Biosciences’ Chief Commercial Officer reported pre-planned open-market sales totaling 6,600 CSTL shares over two days in mid-September 2026.

Rhea-AI Filing Summary

CASTLE BIOSCIENCES INC (CSTL) disclosed that Chief Commercial Officer Juvenal Tobin sold company common stock in two open-market transactions reported on Form 4. On September 14, 2026 he sold 3,306 shares at a weighted-average price of $32.324 per share, and on September 15, 2026 he sold 3,294 shares at a weighted-average price of $35.142 per share. Both sales were made pursuant to a Rule 10b5-1 plan adopted on May 28, 2026, and each was executed in multiple trades within stated price ranges.

Insider Trade Summary 10b5-1

Net Seller: 6,600 shares

Net Sell 2 txns

Insider Juvenal Tobin W

Role Chief Commercial Officer

Sold 6,600 shs ($223K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F3	3,294	$35.142	$116K
Sale	Common Stock F1, F2	3,306	$32.324	$107K

Holdings After Transaction: Common Stock — 58,584 shares (Direct)

Footnotes (3)

1. F1. This transaction was made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on May 28, 2026.
2. F2. This transaction was executed in multiple trades at prices ranging from $32.180 to $32.445, 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. F3. This transaction was executed in multiple trades at prices ranging from $35.000 to $35.380, 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 September 14, 2026: 3,306 shares Weighted-average sale price September 14, 2026: $32.324 per share Price range September 14, 2026: $32.180–$32.445 per share +4 more

7 metrics

Shares sold September 14, 2026 3,306 shares Open-market sale of Castle Biosciences common stock

Weighted-average sale price September 14, 2026 $32.324 per share Common stock sale executed in multiple trades

Price range September 14, 2026 $32.180–$32.445 per share Individual trades within this range; weighted-average price reported

Shares sold September 15, 2026 3,294 shares Open-market sale of Castle Biosciences common stock

Weighted-average sale price September 15, 2026 $35.142 per share Common stock sale executed in multiple trades

Price range September 15, 2026 $35.000–$35.380 per share Individual trades within this range; weighted-average price reported

Total shares sold 6,600 shares Aggregate of reported September 14–15, 2026 sales

Key Terms

Rule 10b5-1 plan, weighted-average sale price, open market or private transaction

3 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 or private transaction financial

"Sale in open market or private transaction"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did CSTL report on this Form 4?

The filing reports that Chief Commercial Officer Juvenal Tobin sold a total of 6,600 shares of Castle Biosciences common stock in two open-market transactions on September 14 and 15, 2026 at weighted-average prices of $32.324 and $35.142 per share, respectively.

How many CSTL shares were sold on each date in this Form 4?

On September 14, 2026, the reporting person sold 3,306 shares of Castle Biosciences common stock. On September 15, 2026, he sold an additional 3,294 shares, for an aggregate of 6,600 shares reported as sold on the Form 4.

At what prices were the CSTL insider sales executed?

The September 14, 2026 sale had a weighted-average price of $32.324 per share, with trades executed between $32.180 and $32.445. The September 15, 2026 sale had a weighted-average price of $35.142 per share, with trades executed between $35.000 and $35.380.

Were the reported CSTL insider sales made under a Rule 10b5-1 plan?

Yes. A footnote states that the transactions were made pursuant to a Rule 10b5-1 plan adopted by the reporting person on May 28, 2026, indicating the sales followed a pre-established trading plan rather than being timed at the insider’s discretion.

Who is the reporting person in Castle Biosciences’ Form 4 for CSTL?

The reporting person is Juvenal Tobin, identified in the filing as Chief Commercial Officer of Castle Biosciences Inc. The Form 4 reports his direct ownership transactions in the company’s common stock.

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

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Available on EDGAR 09/16/2026 - 04:21 PM Accepted by SEC EDGAR 09/16/2026 - 04:20 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)
09/14/2026

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	09/14/2026		S(1)		3,306	D	$32.324(2)	61,878	D
Common Stock	09/15/2026		S(1)		3,294	D	$35.142(3)	58,584	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 May 28, 2026.

2. This transaction was executed in multiple trades at prices ranging from $32.180 to $32.445, 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. This transaction was executed in multiple trades at prices ranging from $35.000 to $35.380, 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	09/16/2026
	** 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)