SEC Form 6-K filed by C3is Inc.

9/29/25 8:00:55 AM ET

$CISS

Marine Transportation

Consumer Discretionary

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6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM

6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE

13a-16

15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of September 2025

Commission File Number

001-41717

C3IS INC.

(Translation of registrant’s name into English)

331 Kifissias Avenue Erithrea 14561 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 ☐

EXHIBIT INDEX


99.1		Management’s Discussion and Analysis of Financial Condition and Results of Operations and Consolidated Financial Statements for the Six Months Ended June 30, 2025

101.INS		Inline XBRL Instance Document

101.SCH		Inline XBRL Taxonomy Extension Schema

101.CAL		Inline XBRL Taxonomy Extension Calculation Linkbase

101.DEF		Inline XBRL Taxonomy Extension Definition Linkbase

101.LAB		Inline XBRL Taxonomy Extension Label Linkbase

101.PRE		Inline XBRL Taxonomy Extension Presentation Linkbase

104		Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101).

*****

This report on Form 6-K, including exhibit 99.1 hereto, is hereby incorporated by reference into the Company’s Registration Statement on Form S-8 (Reg. No. 333-273306) filed with the Securities and Exchange Commission on July 18, 2023 and Registration Statement on Form F-3 (Reg. No. 333- 285135) filed with the Securities and Exchange Commission on February 21, 2025.

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: September 29, 2025


C3IS INC.

By:		/s/ Nina Pyndiah
Name:		Nina Pyndiah
Title:		Chief Financial Officer

Get the next $CISS alert in real time by email

SEC Form 6-K filed by C3is Inc.

9/29/25 8:00:55 AM ET

$CISS

Marine Transportation

Consumer Discretionary

Get the next $CISS alert in real time by email

6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM

6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE

13a-16

15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of September 2025

Commission File Number

001-41717

C3IS INC.

(Translation of registrant’s name into English)

331 Kifissias Avenue Erithrea 14561 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 ☐

EXHIBIT INDEX


99.1		Management’s Discussion and Analysis of Financial Condition and Results of Operations and Consolidated Financial Statements for the Six Months Ended June 30, 2025

101.INS		Inline XBRL Instance Document

101.SCH		Inline XBRL Taxonomy Extension Schema

101.CAL		Inline XBRL Taxonomy Extension Calculation Linkbase

101.DEF		Inline XBRL Taxonomy Extension Definition Linkbase

101.LAB		Inline XBRL Taxonomy Extension Label Linkbase

101.PRE		Inline XBRL Taxonomy Extension Presentation Linkbase

104		Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101).

*****

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: September 29, 2025


C3IS INC.

By:		/s/ Nina Pyndiah
Name:		Nina Pyndiah
Title:		Chief Financial Officer

Get the next $CISS alert in real time by email

SEC Form 6-K filed by C3is Inc.

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SEC Form 6-K filed by C3is Inc.

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Press Releases

C3is Inc. Announces Closing of $2 Million Registered Direct Offering

C3is Inc. Announces Pricing of $2 Million Registered Direct Offering

C3is Inc. reports second quarter and six months 2025 financial and operating results

$CISS
SEC Filings

Amendment: SEC Form SCHEDULE 13D/A filed by C3is Inc.

Amendment: SEC Form SCHEDULE 13D/A filed by C3is Inc.