The stock market's hottest stock, Nvidia, just got a big new backer

• SoftBank Group bought a $4 billion stake in Nvidia, according to Bloomberg News.
• Nvidia has been the best-performing stock in the S&P 500 during the past year, according to FactSet. Its shares are up 202 percent for the past year through Tuesday.

Nvidia, the market's best-performing stock in the past year, just got another big believer for its artificial intelligence aspirations.

Bloomberg News is reporting Japan's SoftBank Group bought a multibillion dollar position in Nvidia.

"SoftBank Group Corp. has quietly amassed a $4 billion stake in Nvidia Corp. making it the fourth-largest shareholder in the graphics chipmaker," the report said, citing people familiar with the situation.

Nvidia shares rallied 202 percent through Tuesday in the previous 12 months compared with the market's 16 percent return in the same time period. That performance ranks number one in the entire , according to FactSet. The shares are up 28 percent this year versus the market's 7 percent performance.

SoftBank's Nvidia position was revealed in the SoftBank Vision Fund $93 billion capital close announcement Saturday. It mentioned the graphics chipmaker as a possible investment transfer from the company's current holdings to the new fund. The release did not specify when the stake was acquired or how much will be moved over.

Billionaire SoftBank founder Masayoshi Son is famous for his early prescient investments in Alibaba and Yahoo, where he rode new technology trends successfully. The investment strategy outlined in the fund's press release revealed why Nvidia may become a holding:

"The Fund will target meaningful, long-term investments in companies and foundational platform businesses that seek to enable the next age of innovation. … The Fund is expected to be active across a wide range of technology sectors, including but not limited to: IoT [internet of things], artificial intelligence, robotics, mobile applications and computing, communications infrastructure and telecoms, computational biology and other data-driven business models, cloud technologies and software, consumer internet businesses and financial technology."

Nvidia's data center cards are used for machine learning and artificial intelligence applications.

"The AI revolution is moving fast and continuing to accelerate," Nvidia CEO Jensen Huang said in a May 9 earnings release, when the company reported better-than-expected fiscal first-quarter earnings. "NVIDIA's GPU deep learning platform is the instrument of choice for researchers, internet giants and startups as they invent the future. … Our Datacenter GPU computing business nearly tripled from last year, as more of the world's computer scientists engage deep learning."

The company's shares were up 1.8 percent Wednesday afternoon.

See the full Bloomberg News report here.