Sam Altman has joined Microsoft to lead a new artificial intelligence project, the tech giant said early Monday, after he was ousted as CEO of OpenAI in a move that sent shockwaves across Silicon Valley.

The chairman and CEO of Microsoft, Satya Nadella announced the move on X just before 3 a.m. ET, more than 48 hours after OpenAI’s board of directors said they “no longer had confidence” in Altman.

Microsoft is a major financial backer of OpenAI, one of the world’s hottest startups, and has invested billions since its first funding deal in 2019. Since then OpenAI has become the most visible of a new generation of AI companies — its ChatGPT, a large language model chatbot, is widely used and has become a symbol of everyday AI innovation.

Nadella said Microsoft was still committed to supporting OpenAI, which now has a new leadership team, while confirming that Altman will lead a “new advanced AI research team,” alongside OpenAI co-founder Greg Brockman, who was ousted as its president on Friday.