Castle Biosciences CCO plans $787K share sale

CASTLE BIOSCIENCES INC (CSTL) received a Rule 144 notice covering potential sales of its common stock by Chief Commercial Officer Tobin Juvenal.

Rhea-AI Filing Summary

CASTLE BIOSCIENCES INC (CSTL) received a Rule 144 notice covering potential sales of its common stock by Chief Commercial Officer Tobin Juvenal. The notice lists 22,500 shares of common stock to be sold through Goldman Sachs & Co. LLC, with an indicated aggregate market value of $787,500, and notes that there were 30,549,507 shares outstanding as of the relevant date.

The shares relate to equity compensation awards, including restricted stock units and restricted stock awards granted between 2022 and 2025. The filing discloses that sales are being made under a selling plan dated December 10, 2025 that is intended to comply with Rule 10b5-1(c), with recent sales reported over the past three months.

Key Figures

Shares to be sold: 22,500 shares of common stock Aggregate market value: $787,500 Shares outstanding: 30,549,507 shares +4 more

7 metrics

Shares to be sold 22,500 shares of common stock Number of Castle Biosciences shares covered by the Rule 144 notice

Aggregate market value $787,500 Aggregate market value of the 22,500 shares to be sold

Shares outstanding 30,549,507 shares Castle Biosciences common shares outstanding for Rule 144 context

Sale on 07/31/2026 17,310 shares for $507,304.17 Reported Rule 144 sale by Tobin Juvenal during past three months

Sale on 08/03/2026 1,730 shares for $48,873.36 Reported Rule 144 sale by Tobin Juvenal during past three months

Sale on 08/17/2026 1,730 shares for $51,191.91 Reported Rule 144 sale by Tobin Juvenal during past three months

Sale on 08/25/2026 1,730 shares for $60,619.02 Reported Rule 144 sale by Tobin Juvenal during past three months

Key Terms

Rule 144, Rule 10b5-1(c), Restricted Stock Units, Restricted Stock Awards, +1 more

5 terms

Rule 144 regulatory

"See the definition of "person" in paragraph (a) of Rule 144."

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

Rule 10b5-1(c) regulatory

"selling plan dated 12/10/2025 that is intended to comply with Rule 10b5-1(c)."

Rule 10b5-1(c) is an SEC guideline that lets company insiders set up a written, pre-planned schedule to buy or sell their company stock when they are not in possession of material, nonpublic information. For investors, it matters because such plans can reduce the appearance of insider trading by separating decisions from inside knowledge—like putting your trades on autopilot—while also requiring scrutiny since pre-planned trades can still affect market confidence and share value.

Restricted Stock Units financial

"Acquired as compensation -- Restricted Stock Units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

Restricted Stock Awards financial

"Acquired as compensation -- Restricted Stock Awards"

Restricted stock awards are company shares given to employees or executives that cannot be sold or transferred until certain conditions — like staying with the company for a set time or meeting performance targets — are met, like a gift that is locked in a safe until rules are satisfied. Investors care because these awards tie management’s pay to company performance, can increase the number of shares outstanding when they become tradable (dilution), and may signal expected future selling pressure or commitment to long-term growth.

Form 144 regulatory

"144: Filer Information"

Form 144 is a document that investors must file with the government when they plan to sell a large number of shares of a company's stock. It helps ensure transparency so everyone knows how many shares are being sold and when, which can impact the stock's price.

FAQ

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

What does the Form 144 filing disclose for CASTLE BIOSCIENCES INC (CSTL)?

It discloses that Chief Commercial Officer Tobin Juvenal may sell 22,500 shares of Castle Biosciences common stock under Rule 144 through Goldman Sachs & Co. LLC, tied to prior equity compensation awards, with sales under a Rule 10b5-1(c) trading plan.

How many CSTL shares are covered by the planned Rule 144 sale?

The notice covers 22,500 shares of Castle Biosciences common stock, with an indicated aggregate market value of $787,500. This amount is disclosed as the number of shares to be sold during the relevant three-month Rule 144 measurement period.

Who is selling CSTL shares under this Form 144 and through which broker?

The selling person is Tobin Juvenal, Chief Commercial Officer of Castle Biosciences, Inc. The broker handling the sales is Goldman Sachs & Co. LLC, which signed the notice on his behalf as the executing firm.

What types of awards generated the CSTL shares being sold?

The shares were acquired as equity compensation from the issuer, including restricted stock units and restricted stock awards granted on several dates between 2022 and 2025, which have produced the common shares eligible for sale.

Is there a trading plan associated with the CSTL Form 144 sales?

Yes. The notice states that the sales are made in connection with a selling plan dated December 10, 2025 that is intended to comply with Rule 10b5-1(c), indicating pre-arranged, formula-based trading instructions.

How many CSTL shares were outstanding relative to the planned sales?

The filing reports that there were 30,549,507 shares of Castle Biosciences common stock outstanding. This figure provides context for the 22,500 shares covered by the Rule 144 notice during the three-month period.

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

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Available on EDGAR 08/25/2026 - 05:46 PM EDT Accepted by SEC EDGAR 08/25/2026 - 05:46 PM EDT Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001856542
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	Castle Biosciences, Inc.
SEC File Number	001-38984
Address of Issuer	1500 W. Parkwood Ave Suite 400 Friendswood TEXAS 77546
Phone	1-866-788-9007
Name of Person for Whose Account the Securities are To Be Sold	Tobin Juvenal
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Chief Commercial Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Goldman Sachs & Co. LLC 200 West Street New York NY 10282	22500	787500	30549507	08/25/2026	NASD

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	08/09/2024	Acquired as compensation -- Restricted Stock Units	Issuer			7159	08/09/2024	Compensation
Common	12/10/2022	Acquired as compensation -- Restricted Stock Units	Issuer			4667	12/10/2022	Compensation
Common	12/10/2022	Acquired as compensation -- Restricted Stock Units	Issuer			1323	12/10/2022	Compensation
Common	03/04/2025	Acquired as compensation -- Restricted Stock Units	Issuer			8238	03/04/2025	Compensation
Common	02/28/2023	Acquired as compensation -- Restricted Stock Awards	Issuer			880	02/28/2023	Compensation
Common	12/09/2023	Acquired as compensation -- Restricted Stock Units	Issuer			233	12/09/2023	Compensation

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Tobin Juvenal 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	08/03/2026	1730	48873.36
Tobin Juvenal 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	08/17/2026	1730	51191.91
Tobin Juvenal 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	07/31/2026	17310	507304.17
Tobin Juvenal 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	08/25/2026	1730	60619.02

144: Remarks and Signature

Remarks	The sales of shares set forth herein are made in connection with a selling plan dated 12/10/2025 that is intended to comply with Rule 10b5-1(c).
Date of Notice	08/25/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	12/10/2025
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	Goldman Sachs & Co. LLC on behalf of Tobin Juvenal
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)