OpenAI co-founder Greg Brockman takes over product and business responsibilities

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, 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.

Leadership Transition

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 road map and helping it scale. She was diagnosed with postural orthostatic tachycardia syndrome (POTS) in 2019, took a medical leave in April, and announced Thursday that she would transition to a part-time advisor role.

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 spoke on condition of anonymity due to confidentiality. He will oversee:

• OpenAI's ChatGPT product business
• Go-to-market teams
• Enterprise teams
• Compute initiatives

"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.

Pressure Ahead of IPO

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 prepares for what is expected to be a historic IPO. OpenAI confidentially filed its prospectus with regulators in June, but the company has not disclosed when it plans to debut and is reportedly delaying until next year.

Competitive Landscape

OpenAI faces increasingly stiff competition from rivals, including:

• Anthropic
• Google
• Elon Musk's SpaceX
• A host of cheaper open-weight models, primarily from China

ChatGPT's market share fell below 50% for the first time in March, according to a report from Sensor Tower. In response, OpenAI has been aggressively promoting its AI coding assistant, Codex, in an effort to win over more users.

Organizational Structure

Sarah Friar, OpenAI's finance chief, and Jason Kwon, the company's strategy chief, will report to Altman. The company does not plan to hire anyone to replace Simo, the source said.

Brockman and Altman's Partnership

Brockman co-founded OpenAI alongside Altman and a group of others, including Musk, in 2015. He and Altman have been close allies. When Altman was briefly ousted 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."

Both were also at the center of a high-profile legal battle earlier this year, when Musk sued OpenAI over its for-profit conversion.