Sam Altman was reinstated late Tuesday as OpenAI’s chief executive, the company said, successfully reversing his ouster by OpenAI’s board last week after a campaign waged by his allies, employees and investors.
The company’s board of directors will be overhauled, jettisoning several members who had opposed Mr. Altman. Adam D’Angelo, the chief executive of Quora, will be the only holdover.
OpenAI had an “agreement in principle” for Mr. Altman to return as chief executive, it said in a post to X. “We are collaborating to figure out the details. Thank you so much for your patience through this.”
The return of Mr. Altman and Greg Brockman, the company’s president who had resigned in solidarity, and the remaking of the board, capped a frenetic five days that upended OpenAI, the maker of the ChatGPT chatbot and one of the world’s highest-profile artificial intelligence companies.
“I love openai, and everything i’ve done over the past few days has been in service of keeping this team and its mission together,” Mr. Altman said in a post to X, adding that he looked forward to reinforcing OpenAI’s partnership with Microsoft, its biggest investor.
OpenAI’s revamped board of directors will include Bret Taylor, an early Facebook officer and former co-chief executive of Salesforce; Lawrence Summers, the former Treasury secretary; and Mr. D’Angelo, a current board member and chief executive of the question and answer site, Quora.
Mr. Taylor will act as board chairman, the company said.
Microsoft supported the move. Satya Nadella, Microsoft’s chief executive, said on X that he was “encouraged by the changes to OpenAI board,” calling it a “first essential step on a path to more stable, well-informed, and effective governance.”
Mr. D’Angelo was leading the negotiations, according to two people in touch with the board. The general framework for the changes was in place by late Sunday, one of those people said.
Determining the composition of the board slowed down the decision to bring Mr. Altman back, according to that person and one other. OpenAI called the new board its “initial” board, indicating it could expand.
A person close to the board’s deliberations on Tuesday said that Mr. D’Angelo, Tasha McCauley and Helen Toner pressed for certain concessions from Mr. Altman, including an independent investigation into his leadership of OpenAI.
In the end, Ms. Toner and Ms. McCauley agreed to step down from the board because it was clear that it needed a fresh start, this person close to deliberations said. If all of them stepped down, they worried that it would suggest the board erred even though they collectively felt they did the right thing, this person said.
The outgoing board focused on curbing Mr. Altman’s power. In addition to an investigation into his leadership, they blocked his and Mr. Brockman’s return to the board and objected to potential board members who they worried might not stand up to Mr. Altman, said this person close to the board negotiations.
OpenAI’s board surprised Mr. Altman and the company’s employees on Friday afternoon when it told him he was being pushed out. Mr. Brockman, who co-founded the company with Mr. Altman and others, resigned in protest.
The ouster kicked off efforts by Mr. Altman, 38, his allies in the tech industry and OpenAI’s employees to force the company’s board to bring him back. On Sunday evening, after a weekend of negotiations, the board said it was going to stick with its decision.
But in a head-spinning development just hours later, Microsoft said that Mr. Altman, Mr. Brockman and others would be joining the company to start a new advanced artificial intelligence lab.
Most of OpenAI’s more than 700 employees signed a letter telling the board they would walk out and follow Mr. Altman to Microsoft if he wasn’t reinstated, putting the future of the start-up in jeopardy.
Four board members — Ilya Sutskever, an OpenAI founder; Mr. D’Angelo; Ms. Toner, a director of strategy at Georgetown’s Center for Security and Emerging Technology; and Ms. McCauley, an entrepreneur and computer scientist — had initially decided to push Mr. Altman out.
But as the employee revolt grew, Mr. Sutskever had second thoughts: “I deeply regret my participation in the board’s actions,” he said in a message on X. He also signed the letter. Mr. Sutskever is no longer on the board but remains an OpenAI employee.
“Ilya is thrilled that Sam is back as C.E.O. and he has been working tirelessly for days to make this happen,” said Mr. Sutskever’s lawyer, Alex Weingarten. “It is what is best for the company.”
OpenAI employees had been given this week off for Thanksgiving, but many workers remained in the office or glued to their screens to follow the drama. “Thank god,” one employee said. “We’re so back,” said another.
Thrive Capital, which is leading a new funding offer than will value OpenAI at more than $80 billion, said it would continue to partner with the company “now and in the future.”
Late on Tuesday night, OpenAI employees were celebrating in the company’s office. Mr. Altman phoned a reporter at The New York Times and said: “I hope you have a lovely Thanksgiving.”