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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."}],"balance_after":18651,"source":{"system":"sec-edgar","filing":"0001877939-26-000086","document":"wk-form4_1790885354.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1877939/000187793926000086/wk-form4_1790885354.xml","form_type":"4"}},{"id":718382,"issuer":{"id":7164,"kind":"organization","name":"Castellum, Inc.","symbol":"CTM"},"owners":[{"id":32972,"kind":"person","name":"Bell David T","position":1,"cik":"0001944338","reported_name":"Bell David T","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":true,"officer_title":"Chief Financial Officer","other_text":"Treasurer"}}],"security":"Common Stock","published_at":"2026-07-02T20:06:25.000Z","date":"2026-07-01","kind":"purchase","planned":false,"acquired":true,"shares":1202,"price":0.612,"value":735.624,"ownership":{"direct":true},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"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."}],"balance_after":17255,"source":{"system":"sec-edgar","filing":"0001877939-26-000060","document":"wk-form4_1783022780.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1877939/000187793926000060/wk-form4_1783022780.xml","form_type":"4"}},{"id":824238,"issuer":{"id":7164,"kind":"organization","name":"Castellum, Inc.","symbol":"CTM"},"owners":[{"id":32972,"kind":"person","name":"Bell David T","position":1,"cik":"0001944338","reported_name":"Bell David T","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":true,"officer_title":"Chief Financial Officer","other_text":"Treasurer"}}],"security":"Common Stock","published_at":"2026-03-31T20:08:27.000Z","date":"2026-03-31","kind":"grant","planned":false,"acquired":true,"shares":1329,"price":0.4544,"value":603.8976,"ownership":{"direct":true},"footnotes":[{"field":"acquired","element":"transactionAcquiredDisposedCode","label":"F1","text":"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."}],"balance_after":16053,"source":{"system":"sec-edgar","filing":"0001944338-26-000002","document":"wk-form4_1774987704.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1877939/000194433826000002/wk-form4_1774987704.xml","form_type":"4"}},{"id":1000427,"issuer":{"id":7164,"kind":"organization","name":"Castellum, Inc.","symbol":"CTM"},"owners":[{"id":32972,"kind":"person","name":"Bell David T","position":1,"cik":"0001944338","reported_name":"Bell David T","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":true,"officer_title":"Chief Financial Officer","other_text":"Treasurer"}}],"security":"Stock Options","published_at":"2025-11-13T11:53:02.000Z","date":"2025-11-11","kind":"grant","planned":false,"acquired":true,"shares":225000,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"In connection with his continued employment, on November 11, 2025 Mr. Bell received 225,000 stock options issued pursuant to the Castellum, Inc. Second Amended 2021 Stock Incentive Plan to purchase 225,000 shares of common stock which vest ratably over twenty months, commencing December 1, 2025."}],"balance_after":225000,"derivative":{"exercise_price":1.19,"expiration_date":"2032-11-10","underlying":"Common Stock","underlying_shares":225000},"source":{"system":"sec-edgar","filing":"0001877939-25-000122","document":"wk-form4_1763034779.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1877939/000187793925000122/wk-form4_1763034779.xml","form_type":"4"}},{"id":1932642,"issuer":{"id":7164,"kind":"organization","name":"Castellum, Inc.","symbol":"CTM"},"owners":[{"id":32972,"kind":"person","name":"Bell David T","position":1,"cik":"0001944338","reported_name":"Bell David T","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"See Remarks"}}],"security":"Stock 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