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 UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of July 2026

Commission File Number: 001-42684

RUBICO INC.
(Translation of registrant’s name into English)

20 Iouliou Kaisara Str

19002, Paiania

Athens – Greece

(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.

Form 20-F ☒          Form 40-F ☐

On July 9, 2026, Rubico Inc. (the “Company”) held a Special Meeting of Shareholders (the “Special Meeting”). At the Special Meeting, the shareholders of the Company approved and adopted a proposal to approve one or more amendments to the Company’s Amended and Restated Articles of Incorporation to effect one or more reverse stock splits of the shares of the Company’s common stock issued and outstanding at the time of the reverse split at a cumulative exchange ratio of between one-for-two and one-for-250, inclusive, with the Company’s board of directors (including any duly constituted committee thereof, the “Board”) to determine, in its sole discretion, whether to implement any reverse stock split, as well as the specific timing and ratio, within such approved range of ratios, and to authorize the Board to implement any such reverse stock split by filing any such amendment with the Registrar of Corporations of the Republic of the Marshall Islands; provided that any such reverse stock split or splits are implemented on or before January 15, 2027.

The information contained in this Report is hereby incorporated by reference into the Company’s registration statement on Form F-3 (File No. 333-297207).

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.

Date: July 10, 2026