SCHEDULE: Imperial Petroleum Adjusts C3is Stake Post-Offering

Imperial Petroleum Inc. updated its beneficial ownership in C3is Inc. to 61.1% following a conversion price adjustment and dilution from a recent registered offering.

Summary

• Imperial Petroleum Inc. (the "Reporting Person") has updated its beneficial ownership in C3is Inc. (the "Issuer") to 12,500,000 shares of Common Stock.
• This represents 61.1% of the Issuer's outstanding Common Stock.
• The update is due to changes in the conversion price of the Issuer's 5.0% Series A Cumulative Convertible Perpetual Preferred Stock, which was adjusted to $1.20 per share.
• The conversion price adjustment resulted from the Issuer's sale of Common Stock in a registered offering, as reported in a prospectus filed on December 11, 2025.
• The percentage ownership also reflects dilution based on the revised total number of outstanding shares of Common Stock, including those issued in connection with the prospectus supplement and upon exercise of outstanding pre-funded warrants.
• Harry N. Vafias, Chairman, CEO, and President of Imperial Petroleum, and Non-Executive Chairman of C3is Inc., beneficially owns 100,577 shares of Common Stock.
• John Kostoyannis and George Xiradakis, directors of both Imperial Petroleum and C3is Inc., own nil shares of Common Stock.
• Imperial Petroleum intends to continuously review its investment and may acquire or sell additional securities, dependent on various factors including the Issuer's financial condition and market conditions.

Sentiment

Score: 5

Explanation: The filing is a factual update on beneficial ownership, reflecting routine adjustments following a corporate financing event. While Imperial Petroleum's percentage ownership was diluted, it maintains a significant majority stake, making the overall sentiment neutral for the reporting person.

Positives

• Imperial Petroleum Inc. maintains a significant majority beneficial ownership stake of 61.1% in C3is Inc.

Negatives

• Imperial Petroleum's percentage ownership in C3is Inc. was diluted due to the Issuer's recent registered offering and the exercise of pre-funded warrants.

Risks

• The Reporting Person's future actions regarding its investment in the Issuer are subject to ongoing evaluation of the Issuer's business, financial condition, operations, prospects, and strategic alternatives.
• Price levels of the Issuer's securities, general market, industry, and economic conditions, and the relative attractiveness of alternative business and investment opportunities could influence the Reporting Person's decisions.
• Tax considerations and the liquidity of the Issuer's securities are also factors that may impact the Reporting Person's investment strategy.

Future Outlook

Imperial Petroleum Inc. intends to continuously review its investment in C3is Inc. and may, from time to time, acquire additional securities or sell existing holdings. The Reporting Person may also engage in discussions with C3is Inc. management, other shareholders, and relevant parties regarding the Issuer's operations, business conduct, and potential extraordinary corporate transactions.

Management Comments

• Imperial Petroleum Inc. intends to review its investment in the Issuer on a continuing basis.
• The Reporting Person may from time to time acquire additional securities of the Issuer, or retain or sell all or portion of the shares then held.
• Any actions undertaken will be dependent upon the Reporting Person's review of numerous factors, including the Issuer's business, financial condition, operations, prospects, and strategic alternatives.

Industry Context

This filing reflects a common occurrence in the public markets where significant shareholders adjust their reported ownership percentages following corporate actions such as equity offerings. The adjustment of a convertible preferred stock's conversion price due to a dilutive event (registered offering) is a standard anti-dilution mechanism. The continued majority stake held by Imperial Petroleum underscores its strategic interest in C3is Inc.

Comparison to Industry Standards

• NA

Related Party Transactions

• Harry N. Vafias serves as the Chairman, Chief Executive Officer, and President of Imperial Petroleum Inc. (the Reporting Person) and is also the Non-Executive Chairman of C3is Inc. (the Issuer).
• John Kostoyannis and George Xiradakis are directors of both Imperial Petroleum Inc. and C3is Inc.

Stakeholder Impact

• Shareholders of C3is Inc. experienced dilution in their ownership percentage due to the registered offering and exercise of pre-funded warrants.
• Imperial Petroleum Inc. shareholders are impacted by the adjusted beneficial ownership in C3is Inc., which remains a majority stake.
• Holders of C3is Inc.'s Series A Convertible Preferred Stock are impacted by the conversion price adjustment to $1.20.

Next Steps

• Imperial Petroleum Inc. will continue to review its investment in C3is Inc. on an ongoing basis.
• The Reporting Person may acquire additional securities or sell existing holdings in the future.
• Discussions may occur with C3is Inc. management and other stakeholders regarding the Issuer's business and potential corporate transactions.

Key Dates

Keywords

C3is Inc., Imperial Petroleum Inc., Schedule 13D, beneficial ownership, common stock, preferred stock, conversion price, dilution, registered offering, SEC filing, Harry N. Vafias