Castellum (CTM) director sells 30,000 shares, retains stake

Rhea-AI Filing Summary

Castellum, Inc. director Charles Thomas McMillen reported an open-market sale of 30,000 shares of common stock at an average price of $0.7043 per share. After this transaction, he directly holds 231,015 shares of Castellum common stock.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

McMillen Charles Thomas

(Last) (First) (Middle)

1103 SOUTH CAROLINA AVENUE

(Street)

WASHINGTON DISTRICT OF COLUMBIA 20003

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Castellum, Inc. [ CTM ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/25/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/25/2026		S		30,000	D	$0.7043	231,015	D(1)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Reflects the issuance of common stock in connection with the cashless exercise of stock options.

Remarks:

	/s/ C. Thomas McMillen	03/27/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did Castellum (CTM) disclose on this Form 4?

Castellum reported that director Charles Thomas McMillen executed an open-market sale of 30,000 shares of common stock at an average price of $0.7043 per share, reducing but not eliminating his direct equity position in the company.

How many Castellum (CTM) shares does the director hold after the sale?

Following the reported transaction, director Charles Thomas McMillen directly holds 231,015 shares of Castellum common stock. This figure represents his remaining stake after selling 30,000 shares in an open-market transaction at an average price of $0.7043 per share.

Was the Castellum (CTM) insider trade a buy or a sell?

The reported Castellum insider trade was a sale. Director Charles Thomas McMillen completed an open-market sale of 30,000 shares of common stock at an average price of $0.7043 per share, as reflected in the Form 4 transaction data.

What price did the Castellum (CTM) director receive per share in the sale?

The director received an average of $0.7043 per Castellum common share sold. This price applies to the 30,000 shares transacted in the open market, as disclosed in the Form 4, and is used to calculate the total value of this insider sale.

Does the Form 4 show any option exercises for Castellum (CTM)?

The summarized data show only a common stock sale by the director, with no derivative or stock option exercises listed. One footnote references stock issued from a cashless option exercise, but no separate derivative transactions appear in the structured transaction records.