OpenAI co-founder Greg Brockman has returned to the artificial intelligence startup three months after taking a leave from his role as president, Bloomberg News reported on Tuesday, citing a person familiar with the matter.

Brockman has been working with CEO Sam Altman on creating a new role for him to focus on significant technical challenges, the report said, citing an internal memo.

His return comes after a series of departures at OpenAI, including its former Chief Technology Officer Mira Murati.

OpenAI and Brockman did not immediately respond to Reuters requests for comment.