In 2000, he put $20 million into Alibaba, the Chinese internet company. As a result of that investment, Mr. Son now owns 30 percent of the $440 billion shopping giant.

Mr. Son and SoftBank became serial acquirers. The company built up positions in the Japanese mobile phone market, including by purchasing the British semiconductor designer ARM Holdings, which develops critical technologies for the mobile market.

More recently, Mr. Son has focused on technology companies in the United States. The vehicle for those efforts will be Mr. Son’s London-based Vision Fund. While the fund represents the vision of Mr. Son, it is bankrolled by Saudi Arabia, which has put up $45 billion — nearly half the fund’s size.

While some have hailed Mr. Son as the Warren Buffett of technology investing, that comparison misses the mark. Mr. Buffett is a forensic analyst of companies rather than trends, and he usually opts for what he perceives to be strong, undervalued brands rather than putting his money into fast-growing, innovative — and risky — firms.

Mr. Son is more entrepreneur than investor in the classic style.

As a university student, he invented a language translator that he sold to a computer company. As an investor, his forte has been identifying futuristic themes and investing based on them. He now is predicting that interconnected devices and artificial intelligence will be the next big trends to disrupt life and industry.

Unlike Mr. Buffett, Mr. Son, 60, relies on an army of hundreds of investment bankers and analysts. They travel the world, identifying potential corporate targets and then structuring deals to acquire them.

But such thematic investing can backfire. Many of Mr. Son’s technology bets fell victim to the 2000 technology crash. And skeptics say the enormous Vision Fund could stumble into bad, overpriced deals as it tries to deploy tens of billions of dollars in a short period of time. One such eyebrow-raising deal was a $300 million investment in Wag, a dog-walking service built around a smartphone app.