SoftBank Group CEO Masayoshi Son, while in San Francisco, made a significant decision regarding Arm Holdings, a chip designer 

Arm's initial public offering (IPO) was in high demand and oversubscribed by 12 times, potentially being priced at $52 per share 

The bankers advising SoftBank recommended leaving an additional $1 per share on the table to maximize the IPO's potential value 

The decision to accept the bankers' recommendation valued Arm at $54.5 billion on a fully diluted basis 

SoftBank had previously agreed to acquire the remaining 25% of Arm from its $100 billion Vision Fund at a valuation of $64 billion 

Concerns about the Vision Fund remaining as an investor post-IPO influenced SoftBank's decision to buy out the remaining stake 

The deal also aimed to boost the Vision Fund's returns and allowed other investors, such as Saudi Arabia's Public Investment Fund and Abu Dhabi's Mubadala, to exit their positions 

SoftBank assured investors of its long-term commitment to Arm and did not sell more shares beyond the initially marketed 9.4% stake 

SoftBank stated that the $64 billion valuation was based on a prior contractual arrangement with the Vision Fund and should not be taken as Arm's true value 

The IPO at a $54.5 billion valuation marked a significant win compared to SoftBank's previous attempt to sell Arm to Nvidia Corp for $40 billion