Japan’s richest man gains $19B in 9 days as other billionaires lose wealth

SoftBank Group's CEO, Masayoshi Son, saw his net worth soar by a staggering $19 billion in just nine days, according to Forbes' real-time data. This surge in wealth comes as SoftBank's shares have increased by 24% in a month and 48% since the start of the year. The recent introduction of OpenAI's latest AI model, GPT-6 Astra, and SoftBank's $30 billion investment into the company in February have fueled investor confidence in the Japanese tech giant.

With previous investments, by the end of October, SoftBank's total funding in OpenAI could surpass $64 billion.

In addition to SoftBank's growth, Arm Holdings, the British chip design company, has also benefited from the AI boom, with its shares surging 128% year-to-date. These gains in Son's assets have enabled him to climb up the global billionaires ranking, from 36th to 28th position in just nine days. However, this wealth expansion stands out as an anomaly among Japanese billionaires.

The four individuals behind Son on the list, Tadashi Yanai, Takemitsu Takizaki, Yasumitsu Shigeta, and Takao Yasuda, all experienced a decline in their net worth over the same period. Yanai's wealth dropped by $2.8 billion to $59.6 billion, Takizaki's fortune fell by $1.5 billion to $23.2 billion, while Shigeta and Yasuda each saw a decline of $200 million each, reducing their assets to $6.2 billion and $4.2 billion, respectively.

While these declines in wealth may seem concerning, it is likely that they are short-lived. Japan's benchmark Nikkei 225 index has fallen by approximately 2.7% over the past month but remains up over 26% this year. Analysts remain optimistic about the Nikkei's future, with a 2026 outlook predicting bullish trends. A survey conducted in August by 10 financial institutions in Japan revealed forecasts for the year-end Nikkei 225 value around 75,000 points, a 15% increase from the current level.