Fidji Simo, the second-highest-ranking executive at OpenAI, is leaving her full-time position, according to the Wall Street Journal. In a staff memo sent Thursday, Simo explained that her ongoing medical leave has turned out to be longer and more challenging than anticipated, and she will now transition into a part-time advisory role. Simo joined OpenAI’s board in 2024 and came on board as CEO of Applications in May 2025—a newly created role reporting directly to Sam Altman that consolidated the company’s business and product operations.

This move was part of a broader restructuring: COO Brad Lightcap, CFO Sarah Friar, and CPO Kevin Weil all began reporting to her, while Altman stepped back to concentrate on research, computing, and safety. Simo first disclosed her health struggles in April, when she announced she was taking medical leave due to a relapse of a neuroimmune condition. In that same memo, it was also revealed that Lightcap had moved into a new “special projects” role and that CMO Kate Rouch was leaving the company to focus on her recovery from cancer. Since then, Weil has also departed.

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Simo came to OpenAI from Instacart, where she had served as CEO since 2021 and guided the company through its 2023 IPO. Before that, she spent over a decade at Meta, including running the Facebook app. Her decision to step back permanently leaves Altman searching for a successor at a critical time, as OpenAI eyes a possible IPO and races to close the enterprise gap with Anthropic. Simo had been widely regarded as a likely candidate to take on even more responsibility once OpenAI went public, making her departure a significant gap for Altman to fill.

Simo’s primary focus was on growing OpenAI’s consumer business. However, ChatGPT’s growth slowed late last year, missing internal revenue targets, which pushed the company to lean more heavily into coding tools—an area where it has been and continues to trail Anthropic for now.