Rubico Inc. (Nasdaq: RUBI) adds MR tanker, lifts backlog to $304.6M

Rhea-AI Filing Summary

Rubico Inc. is updating its offering of up to 50,000,000 common shares and reports an agreement to acquire an additional newbuilding MR tanker by purchasing all shares of an SPV from Top Ships Inc. for approximately $6.25 million, payable in full at closing.

The SPV holds a $45.2 million shipbuilding contract for a 47,499 dwt chemical/product oil carrier scheduled for delivery in the third quarter of 2029, backed by a seven‑year time charter with a major oil trader plus four optional years, for total potential gross revenue of about $75.4 million. A sale and leaseback will fund 85% of installment payments at Term SOFR plus 1.80%, with $0.5 million quarterly installments over 10 years and an $18.2 million balloon.

Following this transaction, total potential gross revenue backlog from Rubico’s two newbuilding MR tankers is approximately $151.0 million, and including time charters for the operating fleet, total potential gross revenue backlog—including optional years—rises by 33% to about $304.6 million. For 2025, Rubico reported net income of $2.6 million, total assets of $134.1 million and stockholders’ equity of $45.8 million.

Filing Explained

The July 15 Form 424B3 is a prospectus update for up to $50,000,000 common shares that incorporates the same-day Form 6-K; it records registered share capacity rather than a completed share issuance.

Key Figures

Share offering size: Up to 50,000,000 common shares SPV purchase price: $6.25 million Shipbuilding contract price: $45.2 million +5 more

8 metrics

Share offering size Up to 50,000,000 common shares Maximum number of common shares referenced in the updated prospectus supplement

SPV purchase price $6.25 million Aggregate purchase price for 100% of the SPV’s shares

Shipbuilding contract price $45.2 million Total purchase price under the shipbuilding contract for the new MR tanker

Installments already paid $6.8 million Portion of the shipbuilding contract price that has already been paid

Contract revenue backlog $75.4 million Total potential gross revenue from the new tanker’s time charter including optional years

Total gross revenue backlog $304.6 million Total potential gross revenue backlog including optional years after the acquisition

2025 net income $2.6 million Net income for 2025 as referenced by Rubico’s CEO

Quarterly lease payments $0.5 million Quarterly installments over 10 years following delivery under the sale and leaseback

Key Terms

Prospectus Supplement, time charter employment, sale and leaseback financing, Term SOFR, +2 more

6 terms

Prospectus Supplement regulatory

"This is a supplement (the “Prospectus Supplement”) to the prospectus"

A prospectus supplement is an additional document provided alongside a company's main offering details, offering updated or extra information about a specific financial product being sold. It helps investors understand the latest terms, risks, and details of the investment, similar to how an update or revision clarifies or expands on original instructions, ensuring they have current and complete information before making a decision.

time charter employment financial

"secured time charter employment for the vessel with a major oil trader"

Time charter employment is a contract where a shipowner leases a vessel to a charterer for a set period while the owner supplies the crew and maintains the ship; the charterer controls where the ship goes and pays a regular hire fee plus fuel and port charges. For investors, time charters matter because they turn ships into predictable income-generators with known utilization and rate exposure, while passing fuel and voyage cost risk to the charterer, which affects cash flow and profitability.

sale and leaseback financing financial

"entered into a sale and leaseback financing agreement with a major Chinese leasing company"

A sale and leaseback is a deal where a company sells an asset it owns—often real estate or equipment—to raise cash, then immediately rents that same asset back from the buyer. Think of selling your house to get money and continuing to live there as a tenant; the company gets liquidity but takes on ongoing rent payments and longer-term obligations. Investors watch these deals because they change cash on hand, reduce owned assets, and alter debt and earnings metrics, affecting valuation and risk.

Term SOFR financial

"The financing bears an interest rate of Term SOFR plus a margin of 1.80%"

Term SOFR is a benchmark interest rate that reflects the cost of borrowing money over a specific period, based on actual transactions in the financial markets. It is used by lenders and borrowers to set the interest rates on loans and financial contracts, helping to ensure rates are fair and transparent. For investors, understanding term SOFR helps gauge borrowing costs and the overall direction of interest rates in the economy.

balloon payment financial

"with a balloon payment of $18.2 million payable together with the last installment"

A balloon payment is a large, single lump-sum due at the end of a loan after a schedule of smaller regular payments; think of it as making modest monthly payments like rent but owing one big bill at the finish. For investors, it matters because the borrower's ability to make or refinance that final payment affects credit risk, cash flow timing and the value of debt or equity tied to that borrower—unexpected shortfalls can cause losses or force restructuring.

gross revenue backlog financial

"total potential gross revenue backlog—including optional years—rises to approximately $304.6 million"

Gross revenue backlog is the total value of customer orders or contracts a company has agreed to deliver but has not yet recognized as sales. Think of it as a restaurant’s list of reservations and advance meal orders: it shows future work and potential income, but some orders may be canceled or adjusted. Investors watch it as an indicator of near-term demand, revenue visibility, and the company’s ability to convert those commitments into reported sales.

Offering Details

shelf

Offering

Offering Type shelf

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Available on EDGAR 07/15/2026 - 04:14 PM Accepted by SEC EDGAR 07/15/2026 - 04:11 PM Learn about SEC filing dates

FAQ

What share offering is Rubico Inc. (RUBI) updating in this prospectus supplement?

Rubico is updating an offering covering up to 50,000,000 common shares. The supplement incorporates new disclosure linked to a tanker acquisition while the broader offering terms remain governed by the existing prospectus dated May 1, 2026.

What acquisition did Rubico Inc. (RUBI) announce on July 15, 2026?

Rubico agreed to buy an SPV from Top Ships Inc. for about $6.25 million. The SPV holds a shipbuilding contract for a 47,499 dwt chemical/product oil carrier delivering in the third quarter of 2029.

How much potential gross revenue backlog will Rubico Inc. (RUBI) gain from the new MR tanker?

The new time charter adds total potential gross revenue of about $75.4 million, including optional years. Overall company potential gross revenue backlog, including optional years, rises to approximately $304.6 million after the transaction.

What are the main financing terms for Rubico Inc.’s (RUBI) newbuilding MR tanker?

The SPV has a sale and leaseback financing covering 85% of shipbuilding installments at Term SOFR + 1.80%. After delivery, Rubico will pay $0.5 million quarterly for 10 years, with a final $18.2 million balloon payment.

When will Rubico Inc.’s (RUBI) newbuilding MR tanker be delivered and how is it employed?

The 47,499 dwt MR tanker is scheduled for delivery in the third quarter of 2029. It is secured on time charter to a major oil trader for a seven‑year firm period plus four optional years.

What were Rubico Inc.’s (RUBI) key 2025 financial results mentioned in the disclosure?

For 2025, Rubico reported net income of $2.6 million, total assets of $134.1 million and stockholders’ equity of $45.8 million. These figures illustrate the company’s current scale alongside its expanding contracted revenue base.

Filed Pursuant to Rule 424(b)(3)

Registration No. 333-295199

Registration No. 333-297277

PROSPECTUS SUPPLEMENT NO. 5

(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 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 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 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.

		Rubico Inc.
		(Registrant)
Date: July 15, 2026		/s/ Nikolaos Papastratis
		Nikolaos Papastratis
		Chief Financial Officer

EXHIBIT 99.1

Rubico Announces Acquisition of Additional Newbuilding MR Tanker and a 33% Increase of Potential Gross Revenue Backlog to About $305 Million

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 entered into a share purchase agreement (the “SPA”) with Top Ships Inc. to purchase the shares of a company (the “SPV”) that is party to a shipbuilding contract with Guangzhou Shipyard International Company Limited and China Shipbuilding Trading Co., Ltd. for the construction of a 47,499 dwt chemical/product oil carrier (the “Newbuilding MR Tanker”). The Newbuilding MR Tanker is scheduled for delivery in the third quarter of 2029.

The aggregate purchase price for 100% of the shares of the SPV is approximately $6.25 million, payable in full at closing. The transaction is expected to close by September 30, 2026, subject to customary closing conditions.

The SPV has secured time charter employment for the vessel with a major oil trader, starting from its delivery and for a firm duration of seven years, with charterer’s option to extend for four additional years. The total potential gross revenue backlog from this contract, including optional years, is about $75.4 million.

The SPV has also entered into a sale and leaseback financing agreement with a major Chinese leasing company for an amount of 85% of the installment payments under the shipbuilding contract. The purchase price under the shipbuilding contract, payable in installments up to the delivery of the vessel, is $45.2 million out of which $6.8 million has already been paid. The financing bears an interest rate of Term SOFR plus a margin of 1.80%. Under the financing, following the delivery of the vessel, the Company will pay quarterly installments of $0.5 million over a period of 10 years with a balloon payment of $18.2 million payable together with the last installment. Top Ships Inc. and the Company will provide corporate guarantees in favor of the leasing company.

The acquisition was approved by a special committee composed of independent and disinterested members of the Company’s board of directors, which obtained a fairness opinion with respect to the consideration paid to acquire the SPV from an independent financial advisor.

Kalliopi Ornithopoulou, the Company’s President, Chairwoman & Chief Executive Officer, stated:

“This acquisition, consistent with our strategy of redeploying capital into our core tanker business, marks a significant milestone that expands our fleet and strengthens our contracted revenue base. As a result, our total potential gross revenue backlog from our two newbuilding MR tankers increases to approximately $151.0 million. Including contracted time charters for our operating fleet, total potential gross revenue backlog—including optional years—rises to approximately $304.6 million, underscoring the strength and visibility of our future cash flows.

Our 2025 financial results, published on March 23, 2026, further highlight the Company’s earnings potential, with net income of $2.6 million, total assets of $134.1 million and stockholders’ equity of $45.8 million.”

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.

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 future revenues and cash flows and the potential acquisition of newbuildings.

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.