Masayoshi Son's net worth has surged by approximately $3.8 billion this year, largely propelled by the soaring stock price of Arm Holdings Plc, thereby enhancing the value of his stakes in SoftBank Group Corp. As one of the top 30 gainers among the world’s 500 wealthiest individuals tracked by the Bloomberg Billionaires Index, Son's net worth reached $15.1 billion as of Tuesday, up from $11.3 billion at the end of last year. He directly benefits from Arm's rally due to his ownership of roughly a third of SoftBank Group, which itself holds a 90% stake in the UK chip designer. Arm's stock surge, fueled by strong AI-driven sales, has nearly tripled since its IPO price of $51, while SoftBank shares are trading near a three-year peak.

Arm's current pricing is likely a "super-premium," especially compared to Nvidia Corp., while Arm's multiples are already rich. Despite this, SoftBank shares trade at a considerable discount to its net asset value (NAV), largely due to challenges faced by its Vision Fund unit. With the Vision Fund 2 still grappling with post-pandemic losses, it contributes about 25.3% to SoftBank's NAV, while Arm accounts for a significant 48.4%. Son's financial obligations, particularly related to side deals at SoftBank Group aimed at boosting his compensation, remain a notable factor.