SoftBank Group's stock hit an all-time high on Monday, as the market bets that the future listing of its stakes in OpenAI and SB Energy could generate substantial returns. Since May 20, SoftBank's stock has risen by 40%, bringing the company's market value to over 40 trillion yen ($252 billion). A two-day surge last week propelled SoftBank's stock higher, following reports that OpenAI is preparing to file an IPO application within the coming days. Power infrastructure company SB Energy also stated it plans to confidentially file for an IPO in the United States. As OpenAI appears to be moving closer to an IPO, market concerns over competitive threats from rivals such as Anthropic, Google, and xAI have eased. Takashi Nakagawa, a senior analyst at TokaiTokyo Intelligence Laboratory, noted that the market is "extremely excited that the long-awaited OpenAI IPO may finally be nearing reality." He added that this move would increase transparency around valuations in the currently somewhat opaque artificial intelligence sector. A significant portion of SoftBank's portfolio consists of AI-driven, unlisted startup companies.