Castellum CFO David T. Bell buys 1,396 shares

The employee stock purchase plan price was set at a 15% discount to Castellum's September 30 closing price.

Rhea-AI Filing Summary

Castellum, Inc. (CTM) Chief Financial Officer and Treasurer David T. Bell purchased 1,396 shares of common stock on October 1, 2026, at $0.5352 per share, leaving him with 18,651 shares held directly. The purchase was made under the 2025 Employee Stock Purchase Plan at a 15% discount to the September 30, 2026 closing price. No Rule 10b5-1 plan is reported.

Insider Trade Summary

Net Buyer: 1,396 shares

Net Buy 1 txn

Insider Bell David T

Role Chief Financial Officer

Bought 1,396 shs ($747.14)

Type	Security	Shares	Price	Value
Purchase	Common Stock F1	1,396	$0.5352	$747.14

Holdings After Transaction: Common Stock — 18,651 shares (Direct)

Footnotes (1)

1. F1. Pursuant to the terms of the Castellum, Inc. 2025 Employee Stock Purchase Plan, the reporting person purchased 1,396 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 September 30, 2026.

Key Figures

Common stock purchased: 1,396 shares Purchase price: $0.5352 per share Direct shares following purchase: 18,651 shares +1 more

4 metrics

Common stock purchased 1,396 shares Purchased by David T. Bell on October 1, 2026

Purchase price $0.5352 per share October 1, 2026 purchase

Direct shares following purchase 18,651 shares David T. Bell's reported holdings after the transaction

Employee Stock Purchase Plan discount 15% Discount to the September 30, 2026 closing price

Key Terms

Employee Stock Purchase Plan, discount, closing price

3 terms

Employee Stock Purchase Plan financial

"terms of the Castellum, Inc. 2025 Employee Stock Purchase Plan"

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.

discount financial

"calculated at a discount of fifteen percent"

A discount is when a security or fund is selling for less than a basic benchmark value — for example the value of the assets behind it, its original face value, or its recent market price. For investors this matters because a discount can be an opportunity to buy cheaper than what you might expect to be the asset’s worth, but it can also signal underlying problems or lower future returns, much like buying a product below sticker price that may come with hidden issues.

closing price financial

"to the closing price of the Registrant's common stock"

FAQ

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

How many CTM shares did the CFO buy, and at what price?

David T. Bell, Castellum's Chief Financial Officer and Treasurer, purchased 1,396 shares at $0.5352 per share on October 1, 2026. The purchase was made under the 2025 Employee Stock Purchase Plan at a 15% discount to the September 30, 2026 closing price.

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

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Available on EDGAR 10/01/2026 - 04:09 PM Accepted by SEC EDGAR 10/01/2026 - 04:09 PM Learn about SEC filing dates

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)
10/01/2026

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	10/01/2026		P		1,396	A	$0.5352(1)	18,651	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 1,396 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 September 30, 2026.

Remarks:

	/s/ David T. Bell	10/01/2026
	** 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)