C3is shares rise 30.92% premarket after SEC filing reveals Imperial Petroleum's 81.9% ownership stake.

C3is Inc. (CISS) surged 30.92% in premarket trading following an SEC filing revealing Imperial Petroleum Inc. owns 81.9% of the company via 9.9 million shares. The filing, dated February 4, disclosed adjustments to C3is’s preferred stock conversion price post-reverse stock split and highlighted overlapping management ties, including Harry N. Vafias, who chairs both companies. This ownership structure, signaling strategic alignment and potential capital support, spurred investor optimism. While other news cited fleet expansion and net asset value growth, these were dated to future periods (2026) and did not directly correlate with the immediate premarket rally. The ownership revelation by Imperial Petroleum, a Greece-based peer, appears to be the primary catalyst for the sharp price increase.