Harry Vafias - 18 Mar 2026 Form 3 Insider Report for C3is Inc. (CISS)

Reporting relationship: Director
Issuer ticker: CISS
Reported as of: 18 Mar 2026
Net transaction value: $0
SEC form: 3
Accepted by SEC: 18 Mar 2026, 16:17:45 UTC
Next SEC filing: 29 Apr 2026
Source filing: View source filing
Reporting owner signature: /s/ Nina Pyndiah, Attorney-in-Fact

Key filing fact

Harry Vafias filed Form 3 for C3is Inc. (CISS) on 18 Mar 2026.

Key facts

This page summarizes Harry Vafias's Form 3 filing for C3is Inc. (CISS).
0 reported transactions and 1 derivative row are listed below.
Accepted by SEC: 18 Mar 2026, 16:17.

Change

No earlier filing in this sequence is available for direct comparison.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Official SEC source

Ownership activity is grounded in SEC Form 3 disclosures.

View source filing

Reporting Owners (1)

CIK 0001328921 Primary reporting owner

Vafias Harry

Relationship: Director
Address: C3IS INC., 331 KIFISSIAS AVENUE ERITHREA, ATHENS, GREECE
Signature: /s/ Nina Pyndiah, Attorney-in-Fact
Signature date: 18 Mar 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

CISS holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 1,162
Date: 18 Mar 2026
Ownership: Direct

CISS holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 3,616
Date: 18 Mar 2026
Ownership: By Arethusa Properties LTD
Footnotes: F1

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

CISS holding Derivative

Stock Option (Right to Buy)

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
Date: 18 Mar 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 500
Exercise price: $348.00
Footnotes: F2

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 2 footnotes

Footnote F1

Shares held by Arethusa Properties LTD ("Arethusa"). The Reporting Person controls Arethusa and may be deemed to beneficially own the securities held by Arethusa by virtue of such control. The Reporting Person disclaims beneficial ownership of such securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of his pecuniary interest therein, if any. This report shall not be deemed an admission that the Reporting Person is the beneficial owner of such securities for purposes of Section 16 of the Exchange Act or for any other purpose.

Footnote F2

50% of the shares subject to such option are vested and exercisable. The remaining 50% of the shares subject to such option vest and become exercisable on September 16, 2026, subject to the Reporting Person's continuous service to the Issuer on such date.

SEC remarks

Exhibit 24 - Power of Attorney