Before Sam Altman was ousted from OpenAI last week, he and the company’s board of directors had been bickering for more than a year. The tension got worse as OpenAI became a mainstream name thanks to its popular ChatGPT chatbot.

Mr. Altman, the chief executive, recently made a move to push out one of the board’s members because he thought a research paper she had co-written was critical of the company.

The news that he was being pushed out came in a videoconference on Friday afternoon, when Mr. Sutskever, who had worked closely with Mr. Altman at OpenAI for eight years, read to him a statement from the board. Though the decision stunned OpenAI’s employees, exposing its board members to tough questions about their qualifications to manage such a high-profile company, it was the culmination of long-simmering boardroom tension.

OpenAI was started in 2015 with an ambitious plan to one day create a superintelligent automated system that can do everything a human brain can do. But friction has long plagued the OpenAI board, which hasn’t even been able to agree on replacements for members who have stepped down.

They said that the subsidiary would be controlled by the nonprofit board and that each director’s fiduciary duty would be to “humanity, not OpenAI investors,” OpenAI said on its website.

After Mr. Altman was forced out and Mr. Brockman left, the four remaining board members are Mr. Sutskever; Adam D’Angelo, the chief executive of Quora, the question-and-answer site; Helen Toner, a director of strategy at Georgetown University’s Center for Security and Emerging Technology; and Tasha McCauley, an entrepreneur and computer scientist.