Few fortunes are as volatile as Masayoshi Son’s.

The SoftBank Group Corp. founder was briefly richer than Bill Gates at the start of the century before tech stocks crashed. In March 2020, as markets sank under Covid-19 and questions swirled over SoftBank’s investments, his wealth dipped to $8.4 billion, the lowest since 2016.

Less than a year later, Japan’s second-richest person has more than quadrupled his fortune to $38 billion, according to the Bloomberg Billionaires Index, hitting the highest level since Bloomberg started tracking billionaire wealth in 2012.