Five years ago, SoftBank chief executive Masayoshi Son announced that he had narrowed his focus and picked out artificial intelligence as the single most important investing theme. The Japanese tech group’s founder had spent more than $140bn on start-ups in a bid to win the shift to AI. Yet his record is poor. A plan to invest in OpenAI will not improve it.

Son largely missed out on the AI-driven corporate valuation surge this year. Now he plans to double down. After the listing of UK chip designer Arm, he wants to splurge tens of billions of dollars on a fresh round of AI bets. Microsoft-backed OpenAI is one of several options SoftBank is considering. It would be expensive. OpenAI was reported to have closed a more than $300mn share sale at a valuation as high as $29bn in April.

Note that SoftBank already had the opportunity to benefit from the AI revolution via Nvidia, whose chip designs are critical to all things generative AI. But SoftBank’s Vision Fund said that it sold its entire stake in Nvidia, worth more than $3bn, in 2019. Since then, Nvidia’s share price is up more than 1,000 per cent.