CSTL Form 144: Insider-Related Sales Listed, 4,017 Shares Planned

Rhea-AI Filing Summary

Filing type: Rule 144 notice for proposed sale of securities by an affiliate of Castle Biosciences (CSTL).

The filer plans to sell 4,017 shares of common stock through Goldman Sachs & Co. LLC on 08/15/2025, with an aggregate market value of $80,701.53. The company reports 29,008,281 shares outstanding. The shares to be sold were acquired on 08/09/2024 as performance awards and were paid as compensation.

The filing also discloses multiple prior sales by related persons in the past three months, including transactions on 06/27/2025 (several sellers totaling multiple thousands of shares with gross proceeds listed) and a larger sale by Derek Maetzold of 43,019 shares on 08/13/2025 for $836,452.83. The notice includes the filers certification regarding absence of undisclosed material adverse information.

Positive

• Disclosure compliance: The filing transparently reports planned sales, acquisition origin (performance awards), and recent related transactions
• Small relative proposed sale: 4,017 shares represent a very small fraction of 29,008,281 outstanding shares

Negative

• Recent concentrated sales: Multiple sales by related trusts and individuals on 06/27/2025 and a large sale of 43,019 shares on 08/13/2025 totaling $836,452.83 could indicate notable insider liquidity
• Potential selling pressure: Aggregated dispositions by related parties within a short period may be perceived negatively by some investors

Insights

Securities Analyst

TL;DR Rule 144 sale appears procedural; specific insider sales in June and August show realized liquidity but not obviously dilutive.

The filing documents a proposed Rule 144 sale of 4,017 shares acquired as performance awards on 08/09/2024, to be executed through Goldman Sachs on 08/15/2025 for about $80.7k. The issuers total shares outstanding are listed as 29,008,281, so the proposed sale represents a de minimis fraction of outstanding stock. However, the schedule of recent transactions shows multiple dispositions in late June 2025 and a substantial single sale of 43,019 shares on 08/13/2025 generating $836,452.83, which may reflect portfolio rebalancing or beneficiary trust liquidity rather than corporate actions. All facts presented are routine disclosures under Rule 144; no earnings or corporate changes are reported.

Corporate Governance / Risk Analyst

TL;DR Multiple insider-related sales were disclosed; monitor for patterns but filing itself is a routine compliance notice.

The notice confirms the securities to be sold were granted as performance compensation and later scheduled for sale under Rule 144. The document lists several related trust and individual sellers with transactions on 06/27/2025 and 08/13/2025 producing material proceeds (for example, $836,452.83 for 43,019 shares). While Rule 144 disclosures are standard, clustered sales by related parties in a short window warrant attention to whether they reflect normal estate/trust distributions or concentrated insider liquidity. The filer also affirms no undisclosed material adverse information, consistent with required certification language.

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	4017	80701.53	29008281	08/15/2025	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	08/09/2024	Acquired as compensation -- Performance Awards	Issuer			4017	08/09/2024	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
The Maetzold Descendants 2020 Trust dtd 12/4/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	06/27/2025	8068	163804.6
The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	06/27/2025	660	13399.98
The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	06/27/2025	660	13399.98
Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	06/27/2025	4944	100378.03
Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	06/27/2025	6924	140577.97
The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	06/27/2025	660	13399.98
The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	06/27/2025	660	13399.98
Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546	Common	08/13/2025	43019	836452.83

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

What is being sold under Castle Biosciences (CSTL) Form 144?

The filer intends to sell 4,017 shares of common stock through Goldman Sachs & Co. LLC on 08/15/2025, with an aggregate market value of $80,701.53.

How were the shares being sold acquired?

The shares were acquired on 08/09/2024 as performance awards from the issuer and were recorded as compensation.

How many shares does Castle Biosciences report outstanding in this filing?

The filing lists total shares outstanding as 29,008,281.

Were there recent related-party sales disclosed in the filing?

Yes. The filing lists several sales on 06/27/2025 by related trusts and individuals and a sale on 08/13/2025 of 43,019 shares for $836,452.83.

Does the filer assert any undisclosed material information about the issuer?

By signing the notice, the person represents they do not know any material adverse information about the issuer that has not been publicly disclosed.