# EDGAR Filing Document

**Accession Number:** 0001951067
**File Stem:** 9999999995-26-001598
**Filing Date:** 2026-5
**Character Count:** 1343
**Document Hash:** ba5667259c9ba915cf159650b228abef
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**9999999995-26-001598.hdr.sgml**: 20260514

**ACCESSION NUMBER**: 9999999995-26-001598

**CONFORMED SUBMISSION TYPE**: EFFECT

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20260513

**DATE AS OF CHANGE**: 20260514

**EFFECTIVENESS DATE**: 20260513

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** C3is Inc.
- **CENTRAL INDEX KEY:** 0001951067
- **STANDARD INDUSTRIAL CLASSIFICATION:** DEEP SEA FOREIGN TRANSPORTATION OF FREIGHT [4412]
- **ORGANIZATION NAME:** 01 Energy & Transportation
- **EIN:** 000000000
- **STATE OF INCORPORATION:** 1T
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** EFFECT
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-272939
- **FILM NUMBER:** 26975600

**BUSINESS ADDRESS:**
- **STREET 1:** 331 KIFISSIAS AVENUE
- **STREET 2:** ERITHREA
- **CITY:** ATHENS
- **STATE:** J3
- **ZIP:** 14561
- **BUSINESS PHONE:** 011-30-210-625-0001

**MAIL ADDRESS:**
- **STREET 1:** 331 KIFISSIAS AVENUE
- **STREET 2:** ERITHREA
- **CITY:** ATHENS
- **STATE:** J3
- **ZIP:** 14561

### UNITED STATES
### SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## Notice of Effectiveness

**Date:** May 13, 2026

**Accession Number:** 0001193125-26-206516

**Form Type:** POS AM

---

**CIK:** 0001951067

**Company Name:** C3is Inc.

**File Number:** 333-272939