SAN FRANCISCO — Greg Brockman, OpenAI's co-founder and president, will now oversee the company's ChatGPT product business, go-to-market teams, enterprise teams, and compute initiatives. This change follows Fidji Simo's departure from her role at OpenAI on Thursday due to chronic illness. The company does not plan to hire a replacement for Simo.

Simo served as OpenAI's product and business chief for approximately one year. She took a medical leave in April, during which Brockman served as the primary leader for product responsibilities. Simo, who was diagnosed with Postural Orthostatic Tachycardia Syndrome in 2019, stated she would transition to a position as a part-time advisor.

Brockman expressed gratitude for her contributions, stating, "I am deeply grateful for all Fidji has done for OpenAI and to advance our mission, and for the opportunity to have worked alongside her for the past few years." Brockman is a co-founder of OpenAI, established in 2015 with Sam Altman and others. In 2023, he briefly resigned from OpenAI in solidarity with Altman when Altman was ousted as CEO, but both rejoined the company days later.

Brockman reports directly to CEO Sam Altman. Other executives reporting to Altman include Sarah Friar, the company's finance chief, and Jason Kwon, the strategy chief. Altman described the leadership dynamic, saying, "Greg and I are partners in running this company." He added, "We have never quite figured out how to communicate that on the org chart, but we will."

OpenAI confidentially filed its prospectus with regulators in June, with a valuation of $852 billion. Regarding the technology, Brockman said, "I think the tech we are developing is transformative." He also stated, "This is going to be the most important technological shift in human history."