That meant a sizable gain for Ellison’s net worth, which is heavily tied to the company.

The 81-year-old entrepreneur co-founder, who currently owns more than 40% of Oracle, subsequently enjoyed a $101 billion surge in wealth overnight, to $393 billion—placing him ahead of Musk’s $385 billion fortune. He joined the likes of Amazon executive chairman Jeff Bezos and LVMH’s Bernard Arnault as the few members of the ultra-rich club to surpass the Tesla CEO since he took the top spot back in 2021.

But Ellison’s ranking as the world’s richest person was short-lived: His estimated net worth fell by $34 billion in the two days following Oracle’s stock surge, according to Bloomberg’s index. Although he has made some wealth gains since, he still stands at a net loss of $23 billion from his high last Wednesday.

And J. Bradford DeLong, a U.C. Berkeley economist, tells Fortune that the sharp downfall was triggered by “second thoughts” around Oracle’s cloud deal with OpenAI.

‘Second thoughts’ about Oracle’s involvement with AI