A two-day wipeout in shares of SoftBank Group Corp has cut US$2.5 billion off the fortune of its founder Masayoshi Son, as the tech investor is buffeted by the Bank of Japan’s (BOJ) earlier-than-expected interest-rate hike.

Shares were down 6.7% in morning trading in Tokyo. Over two days, the technology conglomerate is down roughly 13%. Even after the recent plunge, Son is up about US$3 billion from the US$11.3 billion he began the year with, according to the Bloomberg Billionaires Index.

The billionaire has emerged as one of the hardest hit tycoons in the swift reversal of Japanese stocks. Tokyo-based SoftBank, among the world’s biggest tech investors, had been up 46% through the end of July. It owns most of chipmaker Arm Holdings plc, shares of which soared this year on expectations it can profit from enthusiasm for artificial intelligence. But Arm’s shares plunged 16% Thursday when it disappointed investors by reaffirming an existing annual sales forecast.

On Friday, Japanese shares dropped the most since 2020 as the fallout from tighter monetary policy roiled one of the world’s best-performing markets.

SoftBank’s international operations also mean a strengthening yen poses some risk. Japan’s currency climbed to a four-month high on Thursday following hawkish signals from the BOJ earlier in the week.

Son, 66, is SoftBank’s largest shareholder in the roughly US$78 billion giant, but much of his stake is pledged as collateral against loans with various financial institutions.

  - Bloomberg