AI stock boom delivers bumper quarter for Japan's SoftBank

Japan's SoftBank Group reported Tuesday that net profit more than doubled in the second quarter thanks to a boom in AI-related share prices that has fuelled fears of a market bubble.

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

SoftBank also announced it sold $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 percent 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 $5 trillion. Its market cap has since receded to around $4.8 trillion.

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