Filed Pursuant to Rule 424(b)(3)
Registration No. 333-288796
Registration No. 333-291884
Registration No. 333-293441
Registration No. 333-294944
Registration No. 333-297276
PROSPECTUS SUPPLEMENT NO. 19
(TO PROSPECTUS DATED SEPTEMBER 19, 2025)
Up to 15,000,000 Common Shares
RUBICO INC.
This is a supplement (the “Prospectus Supplement”)
to the prospectus, dated September 19, 2025 (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. 333-288796,
333-291884, 333-293441, 333-294944 and 333-297276), 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 July 15, 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 12 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 July 15, 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 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 [ X ] Form 40-F [ ]
On July 15, 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 July 15, 2026.
The information contained in this Report, except for the commentary of Kalliopi Ornithopoulou
contained in Exhibit 99.1, 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.
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Rubico Inc. |
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(Registrant) |
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| Date: July 15, 2026 |
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/s/ Nikolaos Papastratis |
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Nikolaos Papastratis |
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Chief Financial Officer |
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EXHIBIT 99.1
Rubico Announces Its Decision to Exit the Megayacht Sector and Redeploy
Capital towards its Core Tanker Business
ATHENS, Greece, July 15, 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 it has decided to divest its interest in its newbuilding megayacht currently under construction (the
“Megayacht”) and to exit the megayacht sector. The Company intends to pursue a sale of the Megayacht, or of the entity that
is party to the shipbuilding contract, with the objective of releasing capital for redeployment towards its core tanker business.
The Company believes that focusing on its core tanker business represents
the most effective use of its capital and management resources. A divestment of the Megayacht would allow the Company to redeploy capital
toward its core business, reduce its future capital commitments, and further simplify its asset base.
The Megayacht has a length of 60 meters and a gross tonnage of 1,150
tons and is scheduled for delivery in the second quarter of 2027. Based on independent market estimates obtained by the Company,
for comparable newbuilding megayachts of this size, the Company believes that a sale could generate estimated gross cash proceeds in the
range of €30 to €35 million (about $34.2 to $40 million). Further, the sale would eliminate a capital commitment of €26.5
million ($30.2 million) payable prior to delivery of the Megayacht.
There can be no assurance that a divestment will be completed, or
as to its timing, structure, terms or the proceeds ultimately realized. The Company has not identified a specific use of proceeds of the
sale of the Megayacht and there can be no assurance that the Company will redeploy the net proceeds in the tanker sector. Any transaction
would be subject to the negotiation and execution of definitive agreements, the consent of relevant counterparties and financiers, and
customary conditions. The estimated valuations set forth above are based on third-party market data and management assumptions and may
differ materially from amounts ultimately realized. U.S. dollar amounts in this release are provided for convenience only and are translated
at an exchange rate of €1.00 = $1.14 as of July 14, 2026; actual amounts realized may differ.
Kalliopi Ornithopoulou, the Company’s President, Chairwoman
& Chief Executive Officer, stated:
“Our decision to exit the megayacht sector reflects our intention
to redeploy capital towards our core tanker business. We believe a divestment at current market levels would result in a meaningful equity
release, multiple to the Company’s current market cap, while at the same time eliminating a significant capital commitment.”
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 one 47,499 dwt MR tanker newbuilding scheduled for delivery in the fourth quarter of
2029 and a 60 meter newbuilding megayacht scheduled for delivery in the second quarter of 2027, which the Company intends to divest as
described above.
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 intended divestment of the Company’s megayacht, the estimated
market value of such megayacht, the estimated proceeds and potential equity release that may be realized in connection with a divestment,
and the redeployment of capital.
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.
