[SCHEDULE 13D/A] C3is Inc. SEC Filing

Rhea-AI Filing Summary

C3is Inc. Schedule 13D Amendment No. 3 updates ownership percentages for reporting persons following the issuer's updated count of outstanding shares and issuance on exercise of warrants. The filing is made by Flawless Management Inc., Arethusa Properties LTD and Harry N. Vafias under a Joint Filing Agreement. It discloses post-reverse-split share counts and percentages: Flawless beneficially owns 4 shares (0.01%), Arethusa beneficially owns 72,331 shares (4.5%), and Harry N. Vafias beneficially owns 100,577 shares (6.3%), which includes 5,000 vested option shares and excludes 5,000 unvested options vesting September 16, 2026. Mr. Vafias is identified as Non-Executive Chairman. The amendment notes no transactions in the past 60 days other than the ownership update and attaches a Joint Filing Agreement as Exhibit 1.

Positive

• Transparent update of beneficial ownership to reflect issuer-reported outstanding share count and warrant issuance
• Clear breakdown of holdings by each reporting person including inclusion/exclusion of option shares
• Joint Filing Agreement is attached, clarifying coordinated reporting among the parties

Negative

• Dilution has reduced reported percentage ownerships due to increased outstanding shares and warrant issuances
• No new transaction detail beyond the ownership update; the filing does not report recent acquisitions or dispositions in the past 60 days

Insights

Securities Analyst

TL;DR Ownership percentages were reduced by dilution after the issuer updated its outstanding share count and warrant exercises.

The amendment transparently updates beneficial ownership figures to reflect corporate actions that changed the total share base, including multiple reverse splits previously effected and recent warrant exercises reported by the issuer. The largest holder among the reporting persons remains Harry N. Vafias at 6.3% beneficial ownership, including vested options. The filing confirms no reported trading by the reporting persons in the past 60 days beyond this update and documents a Joint Filing Agreement. For investors, this clarifies current ownership stakes but does not, by itself, indicate a change in control or immediate corporate action.

Corporate Governance Expert

TL;DR A governance disclosure update reconciles ownership percentages after share-count changes and option/warrant activity.

The filing appropriately amends Schedule 13D to reflect dilution from the issuer's updated outstanding share total and exercises of warrants. It discloses Mr. Vafias's dual role as a reporting person and Non-Executive Chairman and specifies option treatment for 5,000 vested and 5,000 unvested shares. The addition of a Joint Filing Agreement as an exhibit formalizes the coordinated reporting. The amendment is procedural and informational rather than signaling new strategic proposals or transactions.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 3)

C3IS INC.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

Y18284169

(CUSIP Number)

Harry N. Vafias
c/o C3is Inc., 331 Kifissias Avenue Erithrea
Athens, J3, 14561
011 30 210 625 0001

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

09/29/2025

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13D

CUSIP No. Y18284169

1

Name of reporting person

Flawless Management Inc.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

MARSHALL ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 4.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 4.00

11

Aggregate amount beneficially owned by each reporting person

4.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0.01 %

14

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13D

CUSIP No. Y18284169

1

Name of reporting person

Arethusa Properties LTD

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

VIRGIN ISLANDS, BRITISH

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 72,331.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 72,331.00

11

Aggregate amount beneficially owned by each reporting person

72,331.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

4.5 %

14

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13D

CUSIP No. Y18284169

1

Name of reporting person

Harry N. Vafias

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

GREECE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 28,242.00
8	Shared Voting Power 72,335.00
9	Sole Dispositive Power 28,242.00
10	Shared Dispositive Power 72,335.00

11

Aggregate amount beneficially owned by each reporting person

100,577.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

6.3 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

* Includes 5,000 shares issuable upon exercise of vested stock options, and excludes 5,000 shares issuable upon exercise of unvested stock options, which vest on September 16, 2026, subject to satisfaction of time-based vesting criteria.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.01 per share
(b)	Name of Issuer: C3IS INC.
(c)	Address of Issuer's Principal Executive Offices: 331 Kifissias Avenue, Erithrea, Athens, GREECE , 14561.
Item 1 Comment: AMENDMENT NO. 3 TO STATEMENT ON SCHEDULE 13D This Amendment No. 3 (this "Amendment No. 3") to Schedule 13D (originally filed on May 20, 2024, as amended by Amendment No. 1 on June 24, 2024 and Amendment No. 2 on September 18, 2024) relates to the common stock, par value $0.01 per share ("Common Stock"), of C3is Inc., a Marshall Islands corporation (the "Issuer"), and is being filed pursuant to a Joint Filing Agreement (attached as Exhibit 1 and incorporated herein by reference) by and between Flawless Management Inc., a Republic of the Marshall Islands corporation ("Flawless"), Arethusa Properties LTD, a British Virgin Islands company ("Arethusa"), and Harry N. Vafias in his personal capacity (sometimes collectively referred to as the "Reporting Persons"). Information given in response to each item below shall be deemed incorporated by reference in all other items below. Unless indicated otherwise, all items left blank remain unchanged, and any items which are amended below are deemed to amend and update the existing items in the Schedule 13D. All share amounts reflect the (1) 1-for-100 reverse split of the Common Stock effected by the Company at 11:59 pm, Eastern Time, on April 11, 2024, (2) 1-for-2.5 reverse split of the Common Stock effected by the Company at 11:59 pm, Eastern Time, on December 31, 2024; and (3) 1-for-6 reverse split of the Common Stock effected by the Company at 11:59 pm, Eastern Time, on April 3, 2025.
Item 3.	Source and Amount of Funds or Other Consideration
	Item 3 of the Statement is hereby amended by adding the following paragraphs to the end of Item 3: This Amendment No. 3 is being filed by the Reporting Persons to update the percentage of shares of Common Stock of the Company beneficially owned by the Reporting Persons to reflect dilution in percentage ownership based on the revised total number of outstanding shares of Common Stock, as reported by the Issuer in the Report on Form 6-K filed with the Securities and Exchange Commission on September 29, 2025, including to reflect the issuance of shares upon exercise of outstanding warrants of the Issuer.
Item 4.	Purpose of Transaction
	The Reporting Persons acquired the securities described in this Schedule 13D for investment purposes and intend to review their investment in the Issuer on a continuing basis. Any Reporting Person may from time to time acquire additional securities of the Issuer, or retain or sell all or a portion of the shares then held by the Reporting Persons, in the open market, block trades, underwritten public offerings or privately negotiated transactions. Any actions any Reporting Person might undertake with respect to its investment in the Issuer may be made at any time and from time to time and will be dependent upon such Reporting Person's review of numerous factors, including, but not limited 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; the relative attractiveness of alternative business and investment opportunities; tax considerations; liquidity of the Issuer's securities; and other factors and future developments. Mr. Vafias serves as the Non-Executive Chairman of the Issuer and therefore regularly engages in discussions with management of the Issuer, the board of directors of the Issuer, other shareholders of the Issuer and other relevant parties, which discussions may include matters ranging from the operations and conduct of the Issuer's business to considering or exploring extraordinary corporate transactions including the events listed in Items 4(a) through 4(j) of Schedule 13D. In connection with these discussions, the Reporting Persons may, either directly or through one or more affiliates, determine to take any available course of action or to take no course of action and may at any time and from time to time take steps to further or implement such course of action, including any of the events listed in Items 4(a) through 4(j) of Schedule 13D. Any action or actions the Reporting Persons may undertake with respect to their investment in the Issuer or the operations and conduct of the Issuer's business will be dependent upon the Reporting Persons' review of numerous factors, including those listed above, and the Reporting Persons specifically reserve the right to change their intentions, or to formulate plans and proposals, with respect to any or all of the matters described in this paragraph, subject to applicable law and regulations.
Item 5.	Interest in Securities of the Issuer
(a)	Item 5 is hereby amended and restated as follows: See Items 11 and 13 on the cover pages to this Statement for the aggregate number and percentage of the class of Common Stock owned by each Reporting Person.
(b)	Number of shares as to which each Reporting Person has: i. Sole power to vote or to direct the vote: See Item 7 on cover pages to this Statement. ii. Shared power to vote or to direct the vote: See Item 8 on cover pages to this Statement. iii. Sole power to dispose or direct the disposition: See Item 9 on cover pages to this Statement. iv. Shared power to dispose or direct the disposition: See Item 10 on cover pages to this Statement.
(c)	Except as set forth in Item 3 to this Schedule, no transactions in the Company's Common Stock by the Reporting Persons were effected in the past 60 days.
(d)	No other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Common Stock beneficially owned by the Reporting Persons.
(e)	Not applicable.
Item 7.	Material to be Filed as Exhibits.
	Item 7 is hereby amended to add the following exhibit: Exhibit 1: Joint Filing Agreement, dated October 1, 2025, among Flawless Management Inc., Arethusa Properties LTD and Harry N. Vafias.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Flawless Management Inc.

Signature:	/s/ Harry N. Vafias
Name/Title:	Harry N. Vafias, President
Date:	10/01/2025

Arethusa Properties LTD

Signature:	/s/ Harry N. Vafias
Name/Title:	Harry N. Vafias, President
Date:	10/01/2025

Harry N. Vafias

Signature:	/s/ Harry N. Vafias
Name/Title:	Harry N. Vafias
Date:	10/01/2025

FAQ

What percentage of C3is Inc. (CISS) does Harry N. Vafias beneficially own after this amendment?

The filing reports that Harry N. Vafias beneficially owns 100,577 shares, representing 6.3% of C3is Inc.

How many shares does Arethusa Properties LTD own according to the Schedule 13D/A?

Arethusa Properties LTD beneficially owns 72,331 shares, representing 4.5% of the class.

Does the filing disclose any recent transactions by the reporting persons in the past 60 days?

No. The amendment states no transactions in the Company's Common Stock by the Reporting Persons were effected in the past 60 days except for the ownership update reflecting dilution.

Are option shares included in the reported ownership for Mr. Vafias?

Yes. The filing includes 5,000 shares issuable upon exercise of vested stock options and excludes 5,000 unvested option shares that vest on September 16, 2026.

Why was Amendment No. 3 filed for Schedule 13D/A?

Amendment No. 3 was filed to update the percentage ownership of the Reporting Persons to reflect dilution based on the issuer's revised total outstanding shares and issuance of shares upon exercise of warrants.