C3is Inc.
CISS- Exchange
- Nasdaq
- Industry
- Deep Sea Foreign Transportation of Freight
- SEC CIK
- 0001951067
No open-market purchases or sales by C3is Inc. insiders were filed in the last 90 days; 3 institutions reported holding it in 13F filings for Q2 2026, worth $123.0K in total; no superinvestor holds it.
Holders of 5% or more of CISS
Holders whose latest Schedule 13D or 13G filing reports 5% or more of C3is Inc., largest stake first. The change is against the holder's previous filing.
| Holder | Latest form | Stake | Change | First filed | Latest filing | Filing |
|---|---|---|---|---|---|---|
| Imperial Petroleum Inc./Marshall Islands | 13D/A | 82.90%7.17M shares | −7.30 ppfrom 90.20% | May 6, 20262 filings | Jun 24, 2026 | SEC |
| Imperial Petroleum Inc./Marshall Islands | 13D/A | 81.90%9.91M shares | – | Feb 4, 20261 filing | Feb 4, 2026 | SEC |
| Imperial Petroleum Inc./Marshall Islands | 13D/A | 74.00%36.3M shares | +12.90 ppfrom 61.10% | Jan 14, 20255 filings | Dec 30, 2025 | SEC |
| Ayrton Capital LLC | 13G | 9.99%856.2K shares | New | Feb 11, 20261 filing | Feb 11, 2026 | SEC |
| Evergreen Capital Management LLC | 13G/A | 9.99%443.2K shares | −0.01 ppfrom 10.00% | Jan 8, 20262 filings | Jan 14, 2026 | SEC |
| S.H.N. Financial Investments Ltd. | 13G | 9.99%443.2K shares | +7.29 ppfrom 2.70% | Nov 14, 20252 filings | Dec 18, 2025 | SEC |
| L1 Capital Global Opportunities Master Fund, Ltd. | 13G | 9.99%443.2K shares | New | Dec 17, 20251 filing | Dec 17, 2025 | SEC |
| Wexford Capital LP | 13G/A | 7.02%112.0K shares | −3.21 ppfrom 10.23% | Sep 24, 20252 filings | Sep 29, 2025 | SEC |
| Towerview LLC | 13G | 6.50%35.0K shares | New | May 18, 20261 filing | May 18, 2026 | SEC |
| Alta Partners LLC | 13G | 5.20%56.2K shares | New | Feb 27, 20261 filing | Feb 27, 2026 | SEC |
| Athanasios Tsiakmakis | 13G/A | 5.02%400.0K shares | −9.34 ppfrom 14.36% | Oct 28, 20252 filings | Jan 13, 2026 | SEC |
Stakes are as of each holder's latest filing. Holders whose last filing was in the old format (before December 18, 2024) have no stake on record and are not listed, and after an acquisition or delisting holders usually stop filing.
13D and 13G filings
25 Schedule 13D and 13G filings on C3is Inc., newest first, including old-format filings without a stake.
| Filed (ET) | Filer | Form | Stake | Change | Event date | Filing |
|---|---|---|---|---|---|---|
| Jun 24, 20264:05 PM ET | Imperial Petroleum Inc./Marshall Islands | 13D/A | 82.90%7.17M shares | −7.30 ppfrom 90.20% | Jun 22, 2026 | SEC |
| May 18, 20263:21 PM ET | Towerview LLC | 13G | 6.50%35.0K shares | New | May 18, 2026 | SEC |
| May 11, 20264:05 PM ET | Evergreen Capital Management LLC | 13G/A | 4.90%27.7K shares | –Below 5% | Mar 31, 2026 | SEC |
| May 6, 20265:15 PM ET | Imperial Petroleum Inc./Marshall Islands | 13D/A | 90.20%4.99M shares | – | May 4, 2026 | SEC |
| Feb 27, 20264:00 PM ET | Alta Partners LLC | 13G | 5.20%56.2K shares | New | Feb 27, 2026 | SEC |
| Feb 11, 20269:57 AM ET | Ayrton Capital LLCand 2 others | 13G | 9.99%856.2K shares | New | Dec 31, 2025 | SEC |
| Feb 4, 20265:00 PM ET | Imperial Petroleum Inc./Marshall Islands | 13D/A | 81.90%9.91M shares | – | Feb 2, 2026 | SEC |
| Jan 14, 20261:55 PM ET | Evergreen Capital Management LLC | 13G/A | 9.99%443.2K shares | −0.01 ppfrom 10.00% | Dec 11, 2025 | SEC |
| Jan 13, 20264:30 PM ET | Athanasios Tsiakmakis | 13G/A | 5.02%400.0K shares | −9.34 ppfrom 14.36% | Jan 9, 2026 | SEC |
| Jan 8, 20261:08 PM ET | Evergreen Capital Management LLC | 13G | 10.00%443.2K shares | New | Dec 11, 2025 | SEC |
| Dec 30, 20255:00 PM ET | Imperial Petroleum Inc./Marshall Islands | 13D/A | 74.00%36.3M shares | +12.90 ppfrom 61.10% | Dec 29, 2025 | SEC |
| Dec 18, 20255:05 PM ET | S.H.N. Financial Investments Ltd. | 13G | 9.99%443.2K shares | +7.29 ppfrom 2.70% | Dec 11, 2025 | SEC |
| Dec 17, 20254:26 PM ET | L1 Capital Global Opportunities Master Fund, Ltd. | 13G | 9.99%443.2K shares | New | Dec 11, 2025 | SEC |
| Dec 15, 20256:05 AM ET | Imperial Petroleum Inc./Marshall Islands | 13D/A | 61.10%12.5M shares | −7.70 ppfrom 68.80% | Dec 12, 2025 | SEC |
| Nov 14, 20258:17 AM ET | S.H.N. Financial Investments Ltd. | 13G/A | 2.70%74.2K shares | –Below 5% | Nov 14, 2025 | SEC |
| Oct 28, 20255:00 PM ET | Athanasios Tsiakmakis | 13G | 14.36%155.0K shares | New | Sep 16, 2025 | SEC |
| Oct 10, 20255:00 PM ET | Imperial Petroleum Inc./Marshall Islands | 13D/A | 68.80%6.00M shares | −18.00 ppfrom 86.80% | Oct 9, 2025 | SEC |
| Oct 10, 20255:00 PM ET | Flawless Management Inc.and 2 others | 13D/A | 3.70%100.6K shares | −2.60 ppfrom 6.30%Below 5% | Oct 9, 2025 | SEC |
| Oct 2, 20259:06 AM ET | Pandora Consultants II SAand 2 others | 13G/A | 2.70%42.9K shares | –Below 5% | Sep 30, 2025 | SEC |
| Oct 1, 20254:15 PM ET | Flawless Management Inc.and 2 others | 13D/A | 6.30%100.6K shares | – | Sep 29, 2025 | SEC |
| Sep 29, 20255:02 PM ET | Wexford Capital LPand 3 others | 13G/A | 7.02%112.0K shares | −3.21 ppfrom 10.23% | Sep 19, 2025 | SEC |
| Sep 24, 20256:44 PM ET | Wexford Capital LPand 3 others | 13G | 10.23%110.4K shares | New | Sep 19, 2025 | SEC |
| Apr 15, 20258:00 PM ET | Imperial Petroleum Inc./Marshall Islands | 13D/A | 86.80%4.94M shares | +13.70 ppfrom 73.10% | Apr 11, 2025 | SEC |
| Feb 14, 20254:37 PM ET | L1 Capital Global Opportunities Master Fund, Ltd. | 13G/A | 4.99%222.7K shares | –Below 5% | Dec 31, 2024 | SEC |
| Jan 14, 20257:00 PM ET | Imperial Petroleum Inc./Marshall Islands | 13D/A | 73.10%11.5M shares | – | Jan 10, 2025 | SEC |
Form 144: proposed insider sales
Notices from officers, directors and other affiliates planning to sell C3is Inc. shares.
No Form 144 notices for C3is Inc. are on file.