Hundreds of OpenAI employees threaten to follow Altman to Microsoft unless board resigns, reports say

Hundreds of OpenAI employees, including co-founder and board member Ilya Sutskever, have signed a letter demanding that either OpenAI's remaining board members resign or those OpenAI employees will join Sam Altman's new venture at Microsoft, reports said.

"Your actions have made it obvious that you are incapable of overseeing OpenAI," the letter obtained by Wired reportedly says. 505 OpenAI employees have signed the letter, Kara Swisher reported, representing the overwhelming majority of OpenAI's headcount. The letter says that Microsoft has "assured" those employees that they would have jobs at the new subsidiary, should they "choose to join."

Signatories reportedly include some of OpenAI's most senior executives. Former interim CEO Mira Murati and OpenAI COO Brad Lightcap are the first two signatories on the letter. Murati was appointed as CEO following Altman's exit but was replaced this morning with Twitch co-founder Emmett Shear.

In an about-face, Sutskever reportedly signed the letter and wrote on the social media platform X Monday morning that he "deeply" regretted his participation in the "board's actions."

Multiple OpenAI employees voiced their support on social media as well. "OpenAI is nothing without its people," the missives said.

Altman was forced out Friday by OpenAI's board, including Sutskever, which cited unspecified issues with his communications. That prompted a backlash from employees and investors, CNBC has previously reported, including Microsoft, Thrive Capital, and Sequoia.

The board then attempted to negotiate Altman's return, but those talks were unsuccessful. Microsoft CEO Satya Nadella on Sunday announced that Altman and fellow OpenAI co-founder Greg Brockman would join the company in a new, largely independent venture. Nadella's announcement also referred to their "colleagues" joining Microsoft, although the number wasn't clear.

Microsoft wasn't immediately available to comment on whether it would hire employees who choose to leave OpenAI. OpenAI wasn't immediately available to comment on the letter.

CNBC's Jordan Novet and Hayden Field contributed to this report.