Despite concerns that the AI boom could be a bubble waiting to burst, there are few signs of it at the moment. The Silicon Valley AI chipmaker Nvidia last week became the world’s first $5tn company and Microsoft and Apple’s valuations hit $4tn, the latter for the first time. A restructuring at OpenAI has valued the company at $500bn and a stake owned by Microsoft at more than $100bn. This could lead to a $1tn flotation as early as next year.