Castle Biosciences (NASDAQ: CSTL) CCO sells stock under 10b5-1 plan

Rhea-AI Filing Summary

CASTLE BIOSCIENCES INC (CSTL) reported that Chief Commercial Officer Juvenal Tobin W sold 1,730 shares of common stock on August 17, 2026 in an open-market or private transaction at a weighted-average price of $29.59 per share, under a Rule 10b5-1 trading plan adopted on December 10, 2025. The trades occurred in multiple lots between $29.21 and $30.01 per share, and Tobin now directly holds 75,964 shares of CSTL common stock.

Insider Trade Summary 10b5-1

Net Seller: 1,730 shares

Net Sell 1 txn

Insider Juvenal Tobin W

Role Chief Commercial Officer

Sold 1,730 shs ($51K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	1,730	$29.59	$51K

Holdings After Transaction: Common Stock — 75,964 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 $29.21 to $30.01, 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: 1,730 shares Weighted-average sale price: $29.59 per share Trade price range: $29.21 to $30.01 per share +3 more

6 metrics

Shares sold 1,730 shares Common stock sold by Chief Commercial Officer on August 17, 2026

Weighted-average sale price $29.59 per share Average price for the 1,730 CSTL shares sold

Trade price range $29.21 to $30.01 per share Price range of multiple trades comprising the reported sale

Shares held after transaction 75,964 shares Direct CSTL common stock holdings of Juvenal Tobin W after the sale

Net shares sold 1,730 shares Net sell activity across all reported transactions in this Form 4

Rule 10b5-1 plan adoption date December 10, 2025 Date Juvenal Tobin W adopted the trading plan used for this sale

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

"transaction_code_description: Sale in open market or private transaction"

FAQ

What insider transaction did CSTL report for Chief Commercial Officer Juvenal Tobin W?

CASTLE BIOSCIENCES INC reported that Chief Commercial Officer Juvenal Tobin W sold 1,730 shares of CSTL common stock on August 17, 2026 at a weighted-average price of $29.59 per share in an open-market or private transaction.

At what prices did the recent CSTL insider sale by Juvenal Tobin W occur?

The reported CSTL insider sale by Juvenal Tobin W was executed in multiple trades at prices ranging from $29.21 to $30.01 per share, with a reported weighted-average sale price of $29.59 per share for the 1,730 shares sold.

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

Following the sale of 1,730 shares, Chief Commercial Officer Juvenal Tobin W directly holds 75,964 CSTL common shares. This post-transaction holding reflects only the position reported in this Form 4 and pertains to direct ownership.

Was the August 17, 2026 CSTL insider sale under a Rule 10b5-1 plan?

Yes. The sale by Juvenal Tobin W of 1,730 CSTL shares on August 17, 2026 was made pursuant to a Rule 10b5-1 plan that he adopted on December 10, 2025, indicating the trades were pre-arranged under that plan.

What type of transaction code was used in the latest CSTL Form 4 filing?

The CSTL Form 4 for Juvenal Tobin W used transaction code S, which indicates a sale in an open market or private transaction. The filing describes a non-derivative transaction in common stock, not an option exercise or derivative conversion.

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

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 08/19/2026 - 04:12 PM Accepted by SEC EDGAR 08/19/2026 - 04:11 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)
08/17/2026

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	08/17/2026		S(1)		1,730	D	$29.59(2)	75,964	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 $29.21 to $30.01, 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	08/19/2026
	** 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)