SoftBank Group has quietly amassed a $4 billion stake in Nvidia, making it the fourth-largest shareholder in the graphics chip-maker, according to people familiar with the situation.

SoftBank, which just closed its Vision Fund, disclosed it owned an unspecified amount of Nvidia stock when it announced $93 billion of commitments to the technology investment fund Saturday. A holding of 4.9 percent, just under the amount that would require a regulatory disclosure in the U.S., would be worth about $4 billion.

A stake in Nvidia fits with SoftBank founder Masayoshi Son's plans to become the biggest investor in technology over the next decade, with bets on emerging trends such as artificial intelligence. Under its founder, Jen-Hsun Huang, Nvidia has become one of the leaders of the charge by chip-makers to provide the underpinnings of machine intelligence in everything from data centers to automobiles.