X0609 4 2026-07-01 0 0001877939 Castellum, Inc. CTM 0001329293 MARTIN TAMMY L false 1934 OLD GALLOWS ROAD, SUITE 350 VIENNA VA 22182 0 1 0 0 General Counsel and Secretary 0 Common Stock 2026-07-01 4 P 0 1202 0.612 A 15031 D Pursuant to the terms of the Castellum, Inc. 2025 Employee Stock Purchase Plan, the reporting person purchased 1,202 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 June 30, 2026. /s/ Tammy L. Martin 2026-07-02