Derek Maetzold sells shares; CSTL (NASDAQ: CSTL) Form 144 lists large late‑2025 trades

Rhea-AI Filing Summary

CSTL filing: Notice of proposed sales of Common Stock by reporting person Derek Maetzold

The filing lists multiple dispositions of Common stock by Derek Maetzold under a Form 144 notice, describing sales executed on various dates and securities acquired by gift and compensation (RSUs, PSUs, options). Several transactions in late 2025 and early 2026 are itemized with share counts and proceeds.

Insights

Insider Trading Analyst

Routine registered sales by an insider with multiple earlier compensation grants and gift acquisitions.

The excerpt lists numerous sales by Derek Maetzold, including large executions such as $651,278.06 for 12/15/2025 (16,847 shares) and $493,526.45 for 12/16/2025 (12,821 shares). The record also shows compensation grants (RSUs, PSUs) dated 03/03/2026–03/04/2026 and earlier option-related activity.

These entries document transactional activity rather than new corporate actions; cash‑flow recipients are the selling holder. Subsequent public filings may provide fuller position context and whether sales were pre‑arranged.

Securities Compliance Attorney

Form 144 notice format and multiple dated dispositions consistent with Rule 144 reporting.

The content itemizes dates, share counts, and gross proceeds for sales, and lists acquisition sources (gift, compensation, option exercise). The filing format aligns with a registered sale notice under securities resale rules.

Compliance implication: confirm any Rule 144 holding‑period and public‑information conditions in related filings; timing and method details may appear in accompanying broker records or Form 4/5 filings.

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	94204	2461550.52	29731198	03/11/2026	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	10/29/2007	Acquired as gift	Derek Maetzold		10/29/2007	1357	10/29/2007	None
Common	10/29/2007	Acquired as gift	Derek Maetzold		10/29/2007	1160	10/29/2007	None
Common	10/29/2007	Acquired as gift	Derek Maetzold		10/29/2007	282	10/29/2007	None
Common	10/29/2007	Acquired as gift	Derek Maetzold		10/29/2007	279	10/29/2007	None
Common	10/29/2007	Acquired as gift	Derek Maetzold		10/29/2007	279	10/29/2007	None
Common	10/29/2007	Acquired as gift	Derek Maetzold		10/29/2007	279	10/29/2007	None
Common	03/04/2026	Acquired as compensation -- Restricted Stock Units	Issuer			17632	03/04/2026	Compensation
Common	03/04/2026	Acquired as compensation -- Restricted Stock Units	Issuer			23534	03/04/2026	Compensation
Common	03/03/2026	Acquired as compensation - Performance Stock Units	Issuer			43176	03/03/2026	Compensation
Common	11/12/2018	Acquired as compensation -- Stock Options	Issuer			6226	11/12/2018	Compensation -- Cashless exercise / same-day sale

* 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
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	02/04/2026	817	30986.44
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	02/03/2026	1339	53295.68
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	02/03/2026	1339	53300.23
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	02/03/2026	522	20932.2
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	01/20/2026	1339	53446.85
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	01/20/2026	1339	53456.36
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	01/20/2026	1339	53588.52
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	01/06/2026	1339	53608.07
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	01/05/2026	1339	50927.53
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	01/05/2026	1339	50917.89
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	12/22/2025	830	33437.46
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	12/17/2025	509	20349.46
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	12/16/2025	12821	493526.45
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	12/15/2025	1339	52323.7
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	12/15/2025	1339	52324.91
Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546	Common	12/15/2025	16847	651278.06

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 does CSTL's Form 144 from Derek Maetzold report?

The Form 144 reports proposed or effected sales of Common stock by Derek Maetzold, listing sale dates, share counts, and gross proceeds. It also lists acquisition sources such as gifts, Restricted Stock Units, Performance Stock Units, and option exercises as recorded in the filing.

How many shares and proceeds are shown for recent large transactions?

The excerpt shows several large dispositions, for example 16,847 shares generating $651,278.06 on 12/15/2025 and 12,821 shares generating $493,526.45 on 12/16/2025. These are listed as individual sale entries with gross proceeds.

Does the filing state why Mr. Maetzold sold shares?

The filing lists acquisition sources (gift, compensation, cashless exercise/same‑day sale) but does not state a personal rationale for the sales. The document confines itself to transaction details: dates, share counts, and proceeds without explanatory commentary.

Are recent share grants disclosed alongside the sales in the filing?

Yes. The excerpt records compensation‑related acquisitions including RSUs dated 03/04/2026 (e.g., 17,632 and 23,534 shares) and PSUs dated 03/03/2026 (43,176 shares), as listed under securities information.