SoftBank Group shares surged more than 18% in Tokyo on Thursday as investors flooded back into tech and AI-related stocks. The rally helped push Japan's Nikkei 225 index up 6%, breaking through the 63,000-point level for the first time. Other AI and semiconductor stocks including Renesas, Tokyo Electron, and Advantest also rose sharply as investors piled into Japanese markets after a three-day holiday.

Masayoshi Son's conglomerate is approaching last year's peak before shedding nearly half its value, partly due to concerns about OpenAI exposure. The company is committing another $30 billion to Sam Altman's AI firm despite growing competition. Analysts cite OpenAI's latest model and Arm's performance (SoftBank holds roughly 90%) as key factors in the recovery. Samsung Electronics also hit a $1 trillion market cap after rising 14%, helping push South Korea's Kospi to a record.

SoftBank's financial position has improved dramatically with its loan-to-value ratio now likely around 11%, compared to concerns about exceeding 25% threshold. The conglomerate is seeking liquidity through an OpenAI IPO and plans to list a new AI and robotics company called Roze in the US. David Gibson at MST Financial called the move "big but makes sense" after tech stocks rallied while Japanese markets were closed. The company reports annual results next week.