Greg Brockman, president of OpenAI, arrives at a federal courthouse as the trial in Elon Musk’s lawsuit over OpenAI’s for-profit conversion continues, in Oakland, California, U.S., May 6, 2026.
Manuel Orbegozo | Reuters
There’s a new second-in-command at OpenAI.
Greg Brockman, the company’s president, is officially responsible for OpenAI’s most important and profitable projects after Fidji Simo stepped down from her role on Thursday due to chronic illness.
Simo, a former Meta executive and ex-CEO of Instacart, served as OpenAI’s product and business chief for about a year, focusing the company’s roadmap and helping it scale. Simo, who was diagnosed with Postural Orthostatic Tachycardia Syndrome, or POTS, in 2019, took a medical leave in April, and said Thursday that she would transition to a position as a part-time advisor.
Brockman, an OpenAI co-founder, took over product responsibilities during Simo’s absence, and will continue to lead those efforts, according to a source familiar with the company’s plans who asked not to be named due to confidentiality. Brockman will oversee OpenAI’s ChatGPT product business, as well as its go-to-market teams, enterprise teams and compute initiatives, the person said.
“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 wrote in a post on X on Friday.
Reporting directly to CEO Sam Altman, Brockman is under pressure to bring in revenue and justify OpenAI’s $852 billion valuation, especially as the company gears up for what’s expected to be a historic IPO. OpenAI confidentially filed its prospectus with regulators in June, but the company hasn’t disclosed when it plans to debut and is reportedly delaying until next year.
OpenAI is also facing increasingly stiff competition from rivals, including Anthropic, Google and Elon Musk’s SpaceX, along with a host of cheaper open-weight models primarily out of China.
ChatGPT’s market share fell below 50% for the first time in March, according to a report from Sensor Tower, and OpenAI has been aggressively touting its AI coding assistant, Codex, in an effort to win over more users.
Sarah Friar, OpenAI’s finance chief, and Jason Kwon, the company’s strategy chief, will report to Altman. The company doesn’t plan to hire anyone to replace Simo, the person familiar said.
Brockman co-founded OpenAI alongside Altman and a group of others, including Musk, in 2015. He and Altman have been close allies, and when Altman was briefly ousted from his role as CEO in 2023, Brockman quit the company in solidarity. Both men rejoined OpenAI days later.
“Greg and I are partners in running this company,” Altman wrote in a blog post at the time. “We have never quite figured out how to communicate that on the org chart, but we will.”
They were also both at the center of a high-profile legal brawl earlier this year. Musk sued Brockman, Altman and the company, alleging they went back on commitments they made to keep the the AI lab a nonprofit.
In federal court in Oakland, California in May, Brockman testified about the startup’s early years and pushed back on Musk’s account of events. He was grilled about his personal financial ambitions, his understanding of OpenAI’s structure and Musk’s involvement at the company.
Musk ultimately lost the case after an advisory jury said he waited too long to sue, a verdict that was immediately adopted by a federal judge.
“I think the tech we are developing is transformative,” Brockman said from the witness stand. “This is going to be the most important technological shift in human history.”
