Fidji Simo, one of OpenAI’s top executives, will step down from his role.

Simo, the company’s chief app officer, wrote in X on Thursday that she decided to leave her full-time position and become a part-time consultant.

Simo was on medical leave three months ago. He said Thursday that he would focus on recovery from his long-standing chronic illness, which has no cure.

“During that time, it became clear that the road to recovery would be much longer and more complex than I had anticipated, and that I needed to fully focus on it,” he added.

Simo was diagnosed with postural tachycardia syndrome, or POTS, in 2019. The disorder can cause fainting, severe dizziness, and an elevated heart rate.

She joined OpenAI in 2025, leaving her CEO role at Instacart, which she had led through an initial public offering. He had previously worked at Meta, formerly Facebook, for over a decade.

Former colleagues of Simo told Business Insider earlier this year that they had seen her as a leader who was relentless, empathetic, and very focused on long-term strategy. Simo said he went on a “listening tour” to better understand the company and that his goal was to make OpenAI’s culture feel like a research lab rather than a fledgling tech giant.

While CEO Sam Altman focused on research and IT, Simo said he would boost work on the company’s products and marketing.

In his post, Simo thanked OpenAI’s board of directors, Altman, and the company’s president, Greg Brockman, for their support, and wrote that his journey with his illness had reinforced his belief in the importance of technology.

Altman wrote on

Simo was clear in her own post about the toll the disease has taken.

“It has been a jarring experience to spend my days helping to build the future and at the same time deal with a disabling illness that still has no cure,” he wrote.

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