Castle Biosciences Insider Files Form 144 for $345K Share Sale

Rhea-AI Filing Summary

Castle Biosciences, Inc. (CSTL) – Form 144 overview

The filing reports a proposed sale of 16,932 common shares by insider-related entities, to be executed through Goldman Sachs & Co. LLC around 27 June 2025. At the most recent share count disclosed in the notice (28,872,315 shares outstanding), the planned disposition represents roughly 0.06 % of total shares, indicating a limited potential impact on the public float.

Historical sales disclosed for the preceding three months total 11,288 shares spread across multiple Maetzold family trusts, yielding aggregate gross proceeds of approximately $226,000 (sum of line-item figures). No additional company financial metrics, earnings data, or operational updates are provided in this Form 144.

Key takeaways for investors

• The filing signals continual, but small-scale, insider selling activity.
• Because the quantity is less than 0.1 % of shares outstanding, market impact is expected to be minimal under normal trading volumes.
• No mention is made of a Rule 10b5-1 trading plan; however, the signee affirms lack of undisclosed material adverse information as required by Rule 144.

Overall, the notice is routine and does not, on its own, imply any change in Castle Biosciences’ fundamentals or forward outlook.

Insights

Financial Analyst

TL;DR – Routine Form 144; 16.9k shares (0.06%) to be sold, negligible dilution, neutral signal.

The filing details a modest insider disposition relative to CSTL’s share base. Even if executed in one bloc, $345k in market value is unlikely to create meaningful price pressure for a stock that routinely trades far larger daily volumes. The cadence of earlier trust sales (≈11k shares in Q2-25) likewise appears immaterial. Because no operational data accompany the notice, investors should view it primarily as housekeeping disclosure rather than a commentary on business prospects. I classify the impact as neutral; downside risk is limited to optics of insider selling, while upside is nonexistent.

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

144: Issuer Information

Name of Issuer

SEC File Number

Address of Issuer

Phone

Name of Person for Whose Account the Securities are To Be Sold

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

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	16932	344566.2	28872315	06/27/2025	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	10/29/2007	Acquired as gift	Derek Maetzold		10/29/2007	6051	10/29/2007	None
Common	10/29/2007	Acquired as gift	Derek Maetzold		10/29/2007	5193	10/29/2007	None
Common	08/09/2024	Acquired as compensation -- Performance Awards	Issuer			3708	08/09/2024	Compensation
Common	10/29/2007	Acquired as a gift	Derek Maetzold		10/29/2007	495	10/29/2007	None
Common	10/29/2007	Acquired as a gift	Derek Maetzold		10/29/2007	495	10/29/2007	None
Common	10/29/2007	Acquired as a gift	Derek Maetzold		10/29/2007	495	10/29/2007	None
Common	10/29/2007	Acquired as a gift	Derek Maetzold		10/29/2007	495	10/29/2007	None

* 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
The Maetzold Descendants 2020 Trust dtd 12/4/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/09/2025	1669	33746.01
The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/09/2025	137	2770.04
The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/09/2025	137	2770.04
Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/09/2025	1023	20684.34
Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/09/2025	1432	28954.04
The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/09/2025	137	2770.04
The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/09/2025	135	2729.61
The Maetzold Descendants 2020 Trust dtd 12/4/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/08/2025	348	6970.44
The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/08/2025	28	560.84
The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/08/2025	28	560.84
Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/08/2025	213	4266.39
Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/08/2025	299	5988.97
The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/08/2025	28	560.84
The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/08/2025	30	600.9
The Maetzold Descendants 2020 Trust dtd 12/4/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/21/2025	2017	43402.21
The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/21/2025	165	3550.5
The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/21/2025	165	3550.5
Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/21/2025	1236	26596.5
Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/21/2025	1731	37248
The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/21/2025	165	3550.5
The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	04/21/2025	165	3550.5

144: Remarks and Signature

Remarks

Date of Notice

Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1

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

ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)

FAQ

How many Castle Biosciences (CSTL) shares are proposed for sale in this Form 144?

16,932 common shares are scheduled to be sold.

What percentage of CSTL’s outstanding shares does the 16,932-share sale represent?

Approximately 0.06 % of the 28,872,315 shares outstanding reported in the filing.

Who is the broker handling the CSTL share sale?

The filing lists Goldman Sachs & Co. LLC as broker.

When is the approximate sale date for the shares?

The notice specifies an approximate sale date of 27 June 2025.

How many CSTL shares were sold by related parties in the past three months?

The table shows 11,288 shares previously sold by Maetzold family trusts and related parties.

What is the aggregate market value of the shares to be sold in this filing?

The filing reports an aggregate market value of $344,566.20 for the 16,932 shares.