Castellum counsel buys 1,329 shares via ESPP

Castellum, Inc. reported that General Counsel and Secretary Tammy L. Martin acquired additional common stock through the company’s 2025 Employee Stock Purchase Plan.

Rhea-AI Filing Summary

Castellum, Inc. reported that General Counsel and Secretary Tammy L. Martin acquired additional common stock through the company’s 2025 Employee Stock Purchase Plan. On March 31, 2026, she obtained 1,329 shares of common stock at $0.4544 per share, a 15% discount to the March 30, 2026 NYSE American closing price. Following this transaction, she directly holds 13,829 shares of Castellum common stock.

Insider Trade Summary

Grant/Award: 1,329 shares

Grant/Award 1 txn

Insider MARTIN TAMMY L

Role General Counsel and Secretary

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

Holdings After Transaction: Common Stock — 13,829 shares (Direct)

Footnotes (1)

1. F1. 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.

Key Figures

Shares acquired: 1,329 shares Purchase price: $0.4544 per share Post-transaction holdings: 13,829 shares +1 more

4 metrics

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

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

Post-transaction holdings 13,829 shares Direct ownership after acquisition

ESPP discount 15% discount Versus NYSE American closing price on March 30, 2026

Key Terms

Employee Stock Purchase Plan, common stock, discount of fifteen percent, 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.

common stock financial

"purchased 1,329 shares of common stock of the Registrant"

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

discount of fifteen percent financial

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

NYSE American LLC financial

"closing price of the Registrant's common stock as quoted on the NYSE American LLC"

NYSE American LLC is a U.S. securities exchange where shares and certain options are listed and traded, with a focus on smaller and mid-sized companies and specific listing rules and trading features. For investors, the exchange matters because it shapes how easily a stock can be bought or sold, the pool of buyers and sellers and the transparency and oversight around trading—like a marketplace that sets the stalls, hours and quality checks that affect liquidity and risk.

FAQ

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

What insider transaction did Castellum (CTM) report for Tammy L. Martin?

Castellum reported that General Counsel and Secretary Tammy L. Martin acquired 1,329 shares of common stock. The shares were obtained through the 2025 Employee Stock Purchase Plan, increasing her direct holdings to 13,829 Castellum shares after the transaction.

At what price did Tammy L. Martin acquire Castellum (CTM) shares?

Tammy L. Martin acquired 1,329 Castellum common shares at $0.4544 per share. The price was set under the 2025 Employee Stock Purchase Plan, using a 15% discount to the NYSE American closing price on March 30, 2026.

How many Castellum (CTM) shares does Tammy L. Martin own after this Form 4?

After the reported transaction, Tammy L. Martin directly owns 13,829 Castellum common shares. This reflects the addition of 1,329 shares acquired through the 2025 Employee Stock Purchase Plan as of the March 31, 2026 transaction date.

What plan was used for Tammy L. Martin’s Castellum (CTM) share purchase?

The purchase was made under the Castellum, Inc. 2025 Employee Stock Purchase Plan. This plan allowed her to buy 1,329 common shares at a 15% discount to the March 30, 2026 NYSE American closing price of the stock.

Was Tammy L. Martin’s Castellum (CTM) transaction an open-market trade?

No, the transaction was not an open-market trade. It was a plan-based acquisition classified as a grant or award, executed through Castellum’s 2025 Employee Stock Purchase Plan at a discounted price relative to the March 30, 2026 market close.

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

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Accepted by SEC EDGAR 03/31/2026 - 04:08 PM EDT 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^*

MARTIN TAMMY L

(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)
	General Counsel and Secretary

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	13,829	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/ Tammy L. Martin	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)