The appointments, settled late at night on Sunday, followed Altman's abrupt ousting just days earlier as CEO of the ChatGPT maker and ended speculation that he could return.

Microsoft rushed in to attract some of the biggest names that left OpenAI, including another co-founder Greg Brockman, to keep key talent out of the hands of rivals including Alphabet's Google and Amazon.com while seeking to stabilize OpenAI, in which it has invested billions.