Masayoshi Son, the founder of SoftBank, has made no secret of his plans to become "the biggest investor in technology over the next decade". Last year the Japanese corporation acquired ARM Holdings, and it already had a controlling stake in the US carrier Sprint. Son has even set up a special Billion Vision Fund, which aims to raise $100 billion for the purpose of making strategic technology investments. It's now come to light that SoftBank has used some of the capital to amass a roughly $4 billion stake in the chipmaker Nvidia.

Neither company has specified the exact numbers or dates, but shares of that amount would equate to a holding of around 4.9 percent. That's just below the threshold that would force the companies to make a full disclosure to US regulators. If the shares were bought some time ago it may have been a very shrewd bit of business, as Nvidia's stock tripled in value last year. In fact, the chipmaker's stock has been on the rise every year, so much so that it's now worth more than $80 billion.

The intention of Son's fund, which has already been backed to the tune of $93 billion, is to bet big on trending future technologies, such as artificial intelligence. Nvidia has positioned itself as one of the key players in the race to develop commercial AI, with its chips and data centers offering a base on which other companies can build their services. That makes Nvidia a perfect fit for SoftBank as it seeks to realize its AI ambitions.