Filed Pursuant to Rule 424(b)(3)
Registration No. 333-295199
Registration No. 333-297277
PROSPECTUS SUPPLEMENT NO. 9
(TO PROSPECTUS DATED MAY 1, 2026)
Up to 50,000,000 Common Shares
RUBICO INC.
This is a supplement (the “Prospectus Supplement”)
to the prospectus, dated May 1, 2026 (as supplemented or amended from time to time, the “Prospectus”) of Rubico Inc. (the
“Company”), which forms a part of the Company’s Registration Statement on Form F-1 (Registration Nos. 333-295199 and
333-297277), as amended from time to time.
This Prospectus Supplement is being filed to update
and supplement the information included in the Prospectus with the information contained in the Company’s Report on Form 6-K, furnished
to the U.S. Securities and Exchange Commission (the “Commission”) on September 17, 2026 (the “Form 6-K”). Accordingly,
the Form 6-K is attached to this Prospectus Supplement.
This Prospectus Supplement should be read in conjunction
with, and delivered with, the Prospectus and is qualified by reference to the Prospectus except to the extent that the information in
this Prospectus Supplement supersedes the information contained in the Prospectus.
This Prospectus Supplement is not complete without,
and may not be delivered or utilized except in connection with, the Prospectus, including any amendments or supplements to it.
Investing in our securities involves a high degree
of risk. See “Risk Factors” beginning on page 10 of the Prospectus for a discussion of information that should be considered
in connection with an investment in our securities.
Neither the Commission nor any state securities
commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation
to the contrary is a criminal offense.
The date of this prospectus supplement is September 17, 2026.
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 September 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 [ X ] Form 40-F [ ]
On September 17, 2026, the Registrant issued a press release, a copy of which is attached hereto as Exhibit 99.1 and is incorporated herein by reference.
Exhibit 99.1. Press release dated September 17, 2026.
The information contained in this Report is hereby incorporated by reference into the Registrant’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.
| | | Rubico Inc. |
| | | (Registrant) |
| | | |
| | | |
| Date: September 17, 2026 | | /s/ Nikolaos Papastratis |
| | | Nikolaos Papastratis |
| | | Chief Financial Officer |
| | | |
EXHIBIT 99.1
Rubico Announces Stock Dividend of 0.50 Common Shares for Each
Outstanding Common Share with a Record Date of September 28, 2026
ATHENS, Greece, Sept. 17, 2026 (GLOBE NEWSWIRE) -- Rubico Inc. (Nasdaq:
RUBI) (the “Company” or “Rubico”), a global provider of shipping transportation services specializing in the ownership
of vessels, announced today that its board of directors has declared a stock dividend of 0.50 common shares for each common share outstanding.
The stock dividend will be distributed on or about October 5, 2026 (the “Distribution Date”) to shareholders of record as
of the close of business on September 28, 2026 (the “Record Date”). No fractional shares will be issued in connection with
the stock dividend; any fractional shares resulting from the stock dividend will be paid in cash based on the closing price of the Company’s
common shares on the Nasdaq Capital Market on the Record Date.
In addition, in accordance with the terms of the Company’s outstanding
warrants, as a result of the stock dividend, immediately after the Record Date the exercise price of all of the Company’s warrants
will be reduced by 33.33% and the number of common shares issuable upon exercise of the warrants will be increased by 50%.
As a result of “due bill” trading procedures expected
to be established by Nasdaq, any purchasers of our common shares in the market through the Distribution Date for the stock dividend, expected
to be October 5, 2026, will be entitled to receive the stock dividend, and holders of our common shares will need to hold their shares
through and including the Distribution Date in order to receive the stock dividend.
The Company’s common shares are expected to begin trading on
the Nasdaq Capital Market on a stock dividend-adjusted basis on or about October 6, 2026.
About the Company
Rubico Inc. is a global provider of shipping transportation services
specializing in the ownership of vessels. The Company is an international owner and operator of two modern, fuel efficient, eco 157,000
dwt Suezmax tankers. Furthermore, the Company owns two 47,499 dwt MR tanker newbuildings scheduled for delivery in the third and fourth
quarters of 2029 and a 60-meter newbuilding megayacht scheduled for delivery in the second quarter of 2027, which the Company intends
to divest. In addition, the Company has entered into a share purchase agreement to acquire a shipowning company that owns one high-specification
47,499 dwt MR tanker newbuilding scheduled for delivery in the second quarter of 2029, with closing of this share purchase agreement to
occur by September 30, 2026.
The Company is incorporated under the laws of the Republic of the
Marshall Islands and has executive offices in Athens, Greece. The Company's common shares trade on the Nasdaq Capital Market under the
symbol “RUBI”.
Please visit the Company’s website at: https://rubicoinc.com/
For further information please contact:
Nikolaos Papastratis
Chief Financial Officer
Rubico Inc.
Tel: +30 210 812 8107
Email: npapastratis@rubicoinc.com
Forward-Looking Statements
Matters discussed in this press release may constitute forward-looking statements. The
Private Securities Litigation Reform Act of 1995 provides safe harbor protections for forward-looking statements in order to encourage
companies to provide prospective information about their business. Forward-looking statements include statements concerning plans, objectives,
goals, strategies, future events or performance, and underlying assumptions and other statements, which are other than statements of historical
facts, including statements regarding the declaration and payment of the stock dividend and the adjustment of the terms of the Company’s
outstanding warrants.
The Company desires to take advantage of the safe harbor provisions of the Private Securities
Litigation Reform Act of 1995 and is including this cautionary statement in connection with this safe harbor legislation. The words “believe,”
“anticipate,” “intends,” “estimate,” “forecast,” “project,” “plan,”
“potential,” “may,” “should,” “expect,” “pending” and similar expressions
identify forward-looking statements. The forward-looking statements in this press release are based upon various assumptions, many of
which are based, in turn, upon further assumptions, including without limitation, our management's examination of historical operating
trends, data contained in our records and other data available from third parties. Although we believe that these assumptions were reasonable
when made, because these assumptions are inherently subject to significant uncertainties and contingencies which are difficult or impossible
to predict and are beyond our control, we cannot assure you that we will achieve or accomplish these expectations, beliefs or projections.
Please see the Company’s filings with the Securities and Exchange Commission for a more complete discussion of these and other risks
and uncertainties. The information set forth herein speaks only as of the date hereof, and the Company disclaims any intention or obligation
to update any forward-looking statements as a result of developments occurring after the date of this communication.
