Castellum (NYSE: CTM) COO boosts stake through purchase plan

Rhea-AI Filing Summary

Castellum, Inc. Chief Operating Officer Andrew Merriman acquired 1,329 shares of common stock through the company’s 2025 Employee Stock Purchase Plan at a per share purchase price of $0.4544. Following this plan purchase, he directly holds a total of 537,329 Castellum common shares.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Merriman Andrew

Role Chief Operating Officer

Type	Security	Shares	Price	Value
Grant/Award	Common Stock	1,329	$0.4544	$603.90

Holdings After Transaction: Common Stock — 537,329 shares (Direct)

Footnotes (1)

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Key Figures

Shares acquired: 1,329 shares Purchase price: $0.4544 per share Post-transaction holdings: 537,329 shares +1 more

4 metrics

Shares acquired 1,329 shares Common Stock acquired on March 31, 2026

Purchase price $0.4544 per share Per share purchase price under 2025 Employee Stock Purchase Plan

Post-transaction holdings 537,329 shares Total direct Castellum common shares held after transaction

Plan discount 15% Discount to March 30, 2026 NYSE American closing price

Key Terms

2025 Employee Stock Purchase Plan, per share purchase price, NYSE American LLC

3 terms

2025 Employee Stock Purchase Plan financial

"Pursuant to the terms of the Castellum, Inc. 2025 Employee Stock Purchase Plan, the reporting person purchased 1,329 shares"

per share purchase price financial

"The per share purchase price was calculated at a discount of fifteen percent"

The per share purchase price is the amount of money paid to buy each individual share of a company's stock. It helps investors understand how much they are paying for a single unit of ownership in the company. This figure is important because it influences investment decisions and reflects the value placed on the company at the time of purchase.

NYSE American LLC financial

"to the closing price of the Registrant's common stock as quoted on the NYSE American LLC on March 30, 2026"

Form 4 Insider Transactions: What Each Field Means →

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

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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^*

Merriman Andrew

(Last) (First) (Middle)

1934 OLD GALLOWS ROAD

SUITE 350

(Street)

VIENNA VIRGINIA 22182

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/31/2026

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	03/31/2026		A		1,329	A(1)	$0.4544	537,329	D

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. Pursuant to the terms of the Castellum, Inc. 2025 Employee Stock Purchase Plan, the reporting person purchased 1,329 shares of common stock of the Registrant. The per share purchase price was calculated at a discount of fifteen percent to the closing price of the Registrant's common stock as quoted on the NYSE American LLC on March 30, 2026.

Remarks:

	/s/ Andrew Merriman	03/31/2026
	** 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 did Castellum (CTM) COO Andrew Merriman report in this Form 4?

Andrew Merriman reported acquiring 1,329 Castellum common shares. The acquisition occurred through the 2025 Employee Stock Purchase Plan at $0.4544 per share, increasing his direct ownership position to 537,329 shares following the transaction.

How many Castellum (CTM) shares did the COO acquire and at what price?

The COO acquired 1,329 shares of Castellum common stock at a per share purchase price of $0.4544. This purchase was executed under the company’s 2025 Employee Stock Purchase Plan, which provided the shares at a discounted price.

What is Andrew Merriman’s total Castellum (CTM) shareholding after this transaction?

After the reported transaction, Andrew Merriman directly holds 537,329 shares of Castellum common stock. This figure reflects his position following the 1,329-share acquisition under the 2025 Employee Stock Purchase Plan disclosed in the Form 4 filing.

How were the new Castellum (CTM) shares acquired by the COO?

The COO obtained the 1,329 shares through Castellum’s 2025 Employee Stock Purchase Plan. According to the disclosure, the per share purchase price was set at a 15% discount to the closing price on the NYSE American as of March 30, 2026.

What discount applied to the Castellum (CTM) shares under the 2025 Employee Stock Purchase Plan?

The 2025 Employee Stock Purchase Plan provided a 15% discount to the closing price of Castellum’s common stock on March 30, 2026. Based on this plan formula, Andrew Merriman purchased 1,329 shares at a per share price of $0.4544.