The tech investment giant logged a net profit of ¥2.5 trillion (US$16.2 billion) in July-September, up from ¥1.2 trillion in the same period last year.

SoftBank also announced it sold US$5.8 billion worth of shares in US chip giant Nvidia last month, after the quarter had ended.

SoftBank Group’s earnings often swing dramatically because it invests heavily in tech start-ups and semiconductor firms, whose stocks are volatile.

In recent months optimism over the promise of AI technology has sparked a rush of multi-billion-dollar deals – sending tech shares soaring worldwide.

Wall Street’s tech-rich Nasdaq index has surged 25% since May.

But that has fed concerns of a market bubble that could eventually burst, like the dot-com boom that imploded at the turn of the millennium.

Nvidia, whose chips are used to train and power generative AI systems, recently became the world’s first company valued above US$5 trillion. Its market cap has since receded to around US$4.8 trillion.

SoftBank, ChatGPT-maker OpenAI and cloud giant Oracle are also leading the US$500 billion Stargate project to build AI infrastructure in the US.