Masayoshi Son, founder and CEO of Japanese multinational investment company SoftBank Group, is one of the richest people in the world.

Son recently announced SB OpenAI Japan, a joint venture with Open AI CEO Sam Altman to bring artificial intelligence services to companies in Japan. As part of the agreement, Son will pay $3 billion to use OpenAI's technology across SoftBank companies. Son is also in talks to invest up to $43 billion in OpenAI, which would be the largest investment in a startup ever, according to The Wall Street Journal.

Son's SoftBank is also part of a $500 billion joint venture announced in late January by Donald Trump with Oracle and OpenAI to build AI infrastructure in the United States.

Son, considered one of the world's most powerful investors, has invested in various companies, including Uber, Yahoo!, DoorDash, Alibaba, the ill-fated WeWork, and more.

Son has an estimated net worth of $17 billion, according to Bloomberg. Here's how Son made his billions.

SoftBank Group

Son founded SoftBank Group in 1981 and grew it into a conglomerate and investment giant funding major startups across various industries including AI, e-commerce, robotics, satellites, marketing and finance.

Son's wealth is driven by his 29% stake in SoftBank. Son is the largest shareholder in the company and owns 421,661 shares as of September 2024.

SoftBank went public in December 2018 and began trading on the Tokyo Stock Exchange after raising more than $21 billion in its initial public offering (IPO).

Among its many acquisitions, SoftBank bought UK-based semiconductor and chip design company, ARM Holdings (ARM), in 2016 for $31 billion. Softbank has a 90% stake in ARM, which has a market cap of $173 billion—meaning Softbank's stake in the company is worth an estimated $155 billion.

SoftBank is invested in more than 400 tech companies such as Uber, Chime, Fanatics, Doordash, India-based food delivery platform Swiggy, Southeast Asia's ride share company Grab, and others through its AI and tech-focused investment funds, Vision Funds 1 and 2.

Real Estate

Son purchased a nine-acre home in Woodside, Calif., for $117.5 million in 2012, which is one of the most expensive homes ever sold in the state, according to San Francisco Business Times. The billionaire also bought the landmark Tiffany building in Tokyo for $326 million in 2013, according to Reuters, and sold it in 2020 for an undisclosed sale price, according to Retalk Asia.