Fidji Simo, OpenAI's second-most senior executive, is permanently stepping down from her full-time position and moving to a part-time advisory role, according to the Wall Street Journal. In a staff note issued on the Thursday, Simo said her ongoing medical leave — for a relapse of a neuroimmune condition first disclosed in April — had proven longer and harder than expected. Her departure matters because she had been widely viewed as a likely successor to take on greater responsibility as OpenAI eyes a possible initial public offering, leaving chief executive Sam Altman with a significant leadership gap to fill.

Simo joined OpenAI's board in 2024 and became CEO of Applications in May 2025, a newly created role consolidating business and product operations, with COO Brad Lightcap, CFO Sarah Friar and CPO Kevin Weil all reporting to her. She arrived from Instacart, where she had been chief executive since 2021, and previously spent over a decade at Meta running the Facebook app. Her exit is one of several recent senior departures — Weil has left, Lightcap moved to "special projects", and CMO Kate Rouch departed for cancer recovery — thinning the executive bench at a company recently valued at $852 billion. The news landed on a busy day, coinciding with the launch of OpenAI's GPT-5.6 model family (Sol, Terra and Luna) and a new ChatGPT Work agent, both framed as targeting rival Anthropic.