San Francisco | The future of OpenAI is in jeopardy after more than 700 of its 770 employees signed a letter on Monday (Tuesday AEDT) saying they may leave the company for Microsoft if the ousted CEO, Sam Altman, is not reinstalled at the high-profile artificial intelligence start-up.

One of the board members who pushed out Mr Altman on Friday reversed course on Monday and signed the letter, which was on an internal message board, according to three people familiar with the matter.