(Bloomberg) -- 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.The surge is closely tied to the rally in SoftBank shares, which represent more than 95% of his net worth and have climbed almost fourfold from a low at the worst of the pandemic-fueled selloff. The Vision Fund -- the world’s largest investment pool for tech startups -- posted its best quarterly profit, while SoftBank sold assets, bought back stock and settled a legal dispute with WeWork Cos. It’s also gathered supporters along the way, with Paul Singer’s Elliott Management Corp. disclosing last year it took a stake as the stock was undervalued.“SoftBank’s current major assets have huge cashflow and will continue to grow,” said Thomas Hayes, chairman of Great Hill Capital. “If he balances his harvesting of winners, with appropriately timed share repurchases, he will avoid a repeat of 2000, even if tech stocks moderate.”SoftBank’s fate has been deeply intertwined with its founder, to the point the relationship recently raised corporate-governance concerns. Son, who’s also chairman and chief executive officer, is personally invested in a unit that poured about $20 billion into tech stocks and derivatives. The 63-year-old, who owns one-third of that division and has denied there was a conflict of interest, said the program was a way to put SoftBank’s cash pile to use.To amplify his leverage, Son uses a common tactic among the ultra-rich -- borrowing against his stock. He just does it much more than most other billionaires.Recently, though, he’s trimmed his pledges as shares of the Japanese giant have become more valuable. Son had committed about one-third of his stake in SoftBank to more than 16 financial institutions as of Feb. 9, down from 38% in September, according to regulatory filings. That still represents about $18 billion -- one of the highest figures among the 500 richest people in the world. The pledges are used as collateral for loans, whose size could be smaller than the value of the committed shares given the recent rally. Bloomberg doesn’t include the value of pledged stock in net-worth calculations.A representative for SoftBank declined to comment for this story.After closing at an all-time high on Wednesday, SoftBank shares slipped 5.3% Thursday amid a decline in the broader stock market. Its Vision Fund last month posted a record profit for the final quarter of 2020, thanks to a boost in the value of its stakes in newly-listed firms including food-delivery service DoorDash Inc. and Chinese online property agent platform KE Holdings Inc.“Since the Vision Fund launched, the number of golden eggs is in accelerating mode,” Son said at a briefing last month. “We are finally in the harvesting stage.”Some 15 companies have gone public from the Vision Fund, and SoftBank may see between 10 and 20 listings a year from its portfolio of 164 startups, he said. Coupang Inc., a South Korean e-commerce giant, is seeking a U.S. IPO and could be valued at more than $50 billion. Compass Inc., one of the largest U.S. real estate brokerages, has filed for a listing, and Chinese truck startup Full Truck Alliance could go public this year. SoftBank has also joined the SPAC bandwagon with plans for several blank-check companies.SoftBank has also had its share of troubles. The Vision Fund has written down its $1.5 billion holding in Greensill Capital and is considering dropping the valuation to near zero, people familiar with the matter have said. At its worst point last year, investors questioned several of SoftBank’s investments, including WeWork, whose IPO spectacularly imploded.The turnaround has been rapid. In addition to improving the outlook for the startups in the Vision Fund, the rally in tech stocks helped boost the value of SoftBank’s stakes in publicly traded firms like Uber Technologies Inc. The Japanese conglomerate also just settled a lawsuit with WeWork and its co-founder, Adam Neumann, paving the way for another attempt at a potential listing of the office-sharing company.“SoftBank Group may expedite its second attempt to list WeWork,” Anthea Lai, a senior analyst at Bloomberg Intelligence, wrote in a March 1 note. “The additional stake should tighten SoftBank’s control and facilitate potential merger talks with special purpose acquisition companies.”(Updates with stock move in 10th paragraph)For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2021 Bloomberg L.P.