Greg Brockman takes charge at OpenAI as Fidji Simo steps down due to illness
OpenAI's co-founder and president absorbs the company's product and commercial operations, just as OpenAI files quietly for a future stock-market debut.
Key points
- Fidji Simo, OpenAI's product and business chief, stepped down on 8 May 2026 due to a chronic illness called POTS and will become a part-time advisor.
- Greg Brockman, an OpenAI co-founder and president, will now oversee ChatGPT, enterprise sales, go-to-market teams and computing efforts.
- OpenAI confidentially filed its IPO prospectus (the formal paperwork required before a company sells shares to the public) with regulators in June 2026.
- OpenAI carries a reported valuation of $852 billion, making it one of the most valuable private companies ever.
- ChatGPT's share of the AI assistant market fell below 50 percent for the first time in March 2026, according to data firm Sensor Tower.
OpenAI just lost one of its most senior executives and handed her responsibilities to one of its founding members, all while quietly preparing to go public.
Fidji Simo, the company's chief of product and business, stepped down on Thursday. She cited postural orthostatic tachycardia syndrome, or POTS, a condition that affects the nervous system and heart rate and can cause severe fatigue and dizziness. Simo was diagnosed with POTS in 2019, took medical leave in April 2026, and will now move to a part-time advisory role.
Greg Brockman steps directly into her shoes. Brockman is one of the people who built OpenAI from scratch alongside CEO Sam Altman back in 2015, and he has been covering Simo's duties since her leave began. He now formally owns the ChatGPT product, OpenAI's enterprise and sales teams, and its computing strategy. He reports directly to Altman.
OpenAI does not plan to hire a replacement for Simo.
The reshuffle lands at a delicate moment. OpenAI secretly filed the paperwork needed for a stock-market listing with US regulators in June 2026, though the company has not named a date and is reportedly pushing the debut to 2027. When a company goes public, it sells shares to everyday investors for the first time, and every detail of its business gets examined closely.
Brockman faces real pressure on that front. ChatGPT, the AI chatbot that most people know by name, held below 50 percent of the AI assistant market in March 2026, according to Sensor Tower. Rivals including Anthropic, Google and a wave of cheaper open-source models (AI systems whose underlying code anyone can download and run) are eating into that lead.
The Brockman-Altman partnership has its own history. When OpenAI's board briefly fired Altman in 2023, Brockman quit the same day in protest. Both returned within days. Altman wrote at the time: "Greg and I are partners in running this company."
Brockman was also in federal court in Oakland in May 2026, testifying in the lawsuit Elon Musk brought against OpenAI and its leadership. Musk alleged the company betrayed its original nonprofit mission. An advisory jury found that Musk had waited too long to file the case, a finding a federal judge immediately upheld.
For the millions of people who use ChatGPT at work or at home, the executive change does not affect how the product works today. What it does signal is that OpenAI is betting heavily on Brockman, its most senior co-founder still in a day-to-day role, to grow revenue and keep the company competitive before investors get their first look.
What does this mean for ordinary ChatGPT users?
Nothing changes today. Your ChatGPT account, your saved chats and your subscription price are unaffected by the leadership shift. The longer-term question is whether Brockman can keep OpenAI ahead of cheaper rivals, which could eventually shape what features the service prioritises and how it is priced. Worth keeping an eye on, not worth panic.
