CSTL files Rule 144 notice for 4,152 shares

CSTL filed a Rule 144 notice reporting proposed sales tied to an exercise of stock options.

Rhea-AI Filing Summary

CSTL filed a Rule 144 notice reporting proposed sales tied to an exercise of stock options. The filing lists 4,152 shares associated with the option exercise dated 06/16/2026 and also shows 25,759 restricted and performance stock units with a 12/31/2025 date.

Insights

Securities Compliance Counsel

Notice of proposed resale under Rule 144; transaction quantities and instrument types are disclosed.

The filing lists an exercise of stock options producing 4,152 shares dated 06/16/2026, and separately enumerates 25,759 restricted and performance stock units dated 12/31/2025. These entries reflect quantities and instrument types rather than completed market sales.

Timing and sale mechanics are not detailed in the excerpt; subsequent filings or broker notices would state actual sale methods and proceeds. Cash‑flow treatment is not specified in the provided excerpt.

Key Figures

Option exercise shares to be sold: 4,152 shares Restricted & performance stock units listed: 25,759 shares Option exercise date: 06/16/2026

3 metrics

Option exercise shares to be sold 4,152 shares exercise of stock options dated 06/16/2026

Restricted & performance stock units listed 25,759 shares Restricted & Performance Stock Units dated 12/31/2025

Option exercise date 06/16/2026 date associated with the 4,152 share option exercise

Key Terms

Rule 144, restricted and performance stock units, exercise of stock options

3 terms

Rule 144 regulatory

"filed a Rule 144 notice reporting proposed sales"

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.

restricted and performance stock units financial

"Restricted & Performance Stock Units | Issuer | ... | 25759 | 12/31/2025"

exercise of stock options financial

"Exercise of Stock Options | Issuer | ... | 4152 | 06/16/2026"

FAQ

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

What does CSTL's Form 144 report?

It reports proposed resale activity under Rule 144. The excerpt lists 4,152 shares tied to an option exercise dated 06/16/2026 and 25,759 restricted/performance units dated 12/31/2025, showing instrument types and quantities.

Does the Form 144 show completed sales for CSTL?

No; the filing is a notice of proposed resale under Rule 144. The excerpt lists quantities (4,152 and 25,759) and dates but does not state consummated market transactions or proceeds.

Who is listed as the broker or purchaser on the CSTL entry?

The excerpt references Morgan Stanley Smith Barney LLC in the securities row. The filing text shows the broker name but does not detail sale execution, pricing, or purchaser identity.

Are the 25,759 units immediately transferable according to the excerpt?

The excerpt lists 25,759 restricted and performance stock units with a 12/31/2025 date. It does not state transferability or any holding-period expiration; those conditions are not provided in the excerpt.

What date is associated with the option exercise in the CSTL filing?

The option exercise entry is dated 06/16/2026 and shows 4,152 shares as the quantity associated with that exercise in the excerpt.

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

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Accepted by SEC EDGAR 06/16/2026 - 04:35 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	0001856565
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	8667889007
Name of Person for Whose Account the Securities are To Be Sold	KRISTEN OELSCHLAGER
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	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	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004	29911	617961.26	30329952	06/16/2026	NASDAQ

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	06/16/2026	Exercise of Stock Options	Issuer			4152	06/16/2026	Cash
Common	12/31/2025	Restricted & Performance Stock Units	Issuer			25759	12/31/2025	N/A

* 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

Nothing to Report

144: Remarks and Signature

Remarks	The securities to be sold will be received upon the exercise of stock options over the next three months. The dates of acquisition and payment will be the dates of exercise/sale. The securities to be sold were acquired upon the vesting of restricted stock units & performance stock units during the period of 12/31/2025 through 03/04/2026.
Date of Notice	06/16/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	03/17/2026
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	/s/ Kristen Oelschlager
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)