6-K - Castor Maritime Inc. (0001720161) (Filer)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13A-16 OR 15D-16 OF

THE SECURITIES EXCHANGE ACT OF 1934

For the month of November 2026

Commission File Number: 001-38802

CASTOR MARITIME INC.

(Translation of registrant’s name into English)

223 Christodoulou Chatzipavlou Street, Hawaii Royal Gardens, 3036 Limassol, Cyprus

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

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INFORMATION CONTAINED IN THIS FORM 6-K REPORT

Attached to this report on Form 6-K as Exhibit 99.1 is a copy of the press release issued by Castor Maritime Inc. (the “Company”) on November 4, 2026, announcing that its majority-owned subsidiary, MPC Oceanic Group AG, entered into an agreement to acquire a 41% stake in Marlow Navigation Co. Ltd.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.