[Form 4] Castellum, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Castellum, Inc. Chief Financial Officer and Treasurer David T. Bell acquired 1,329 shares of common stock, increasing his direct holdings to 16,053 shares. The shares were obtained under Castellum’s 2025 Employee Stock Purchase Plan at a per share price of $0.4544.

According to the plan terms, the purchase price reflected a 15% discount to the closing price of Castellum’s common stock on the NYSE American LLC on March 30, 2026, making this a routine compensation-related stock purchase rather than an open-market trade.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Bell David T

Role Chief Financial Officer

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

Holdings After Transaction: Common Stock — 16,053 shares (Direct)

Footnotes (1)

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Key Figures

Shares acquired: 1,329 shares Purchase price per share: $0.4544 per share Shares owned after transaction: 16,053 shares +1 more

4 metrics

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

Purchase price per share $0.4544 per share Price under 2025 Employee Stock Purchase Plan

Shares owned after transaction 16,053 shares Direct holdings following the reported acquisition

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

Key Terms

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

4 terms

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"

An employee stock purchase plan is a company program that lets workers buy shares through small payroll deductions, often at a discount to the market price and after a set offering period. Think of it like a workplace savings plan that turns into ownership: it encourages employees to share in the company’s success and can create predictable buying or selling of stock that investors watch because it affects supply, demand and employee incentives.

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.

closing price market

"a discount of fifteen percent to the closing price of the Registrant's common stock"

NYSE American LLC market

"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^*

Bell David T

(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)	X	Other (specify below)
	Chief Financial Officer		Treasurer

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	16,053	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/ David T. Bell	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)