SoftBank Group sees $15-bn m-cap loss as its shares plunge most since going public in 1998

A stock rout in Japan wiped out $15 billion of SoftBank Group Corp.’s value on Monday, after the company’s biggest single-day fall since founder Masayoshi Son took the company public in 1998.

The technology giant’s stock fell 19%, extending its decline for the September quarter so far to 38%, in line to be the biggest such drop since 2001. The plunge comes as Son prepares an investment blitz in AI and semiconductor technologies. The global market rout also threatens to hurt SoftBank’s Vision Fund unit, which holds investments in hundreds of technology startups.

The stock turmoil erased $2.9 billion of Son’s own personal wealth in a single day, according to the Bloomberg Billionaires Index. Son’s seen more than $5 billion of his worth vanish over the last three trading days, erasing much of his wealth gains since the start of the year and making him one of the hardest-hit tycoons in Asia.

“AI’s hype is fading now that there’s a greater focus on AI companies’ ability to deliver revenue and earnings,” Bloomberg Intelligence analysts Marvin Lo and Chris Muckensturm wrote in a note. “SoftBank’s AI investment strategy might help the company return to profitability, but it might not be smooth sailing with execution risk high.”