Andrew Tulloch, the star AI researcher who was offered a pay package worth more than $1 billion to join Meta Platforms last year, is leaving the company, according to people familiar with the situation.

Tulloch's hiring was a coup for Meta and capped a frantic recruiting spree last summer, when Meta threw money at researchers to try to catch up in the race to build artificial intelligence. He had spent 11 years at Meta before leaving in 2023 for OpenAI and then co-founding Thinking Machines.