OpenAI has lost a string of senior leaders in 2026, extending a period of management turnover at the ChatGPT maker. Departures named in the source include former operating chief Brad Lightcap, applications CEO Fidji Simo, chief revenue officer Denise Dresser, and executives responsible for marketing, enterprise products, science, safety, and ethics. Some left to start new ventures, while others stepped back for health reasons. The exits come after another round of turnover in 2025, when OpenAI lost its chief people and communications officers, a top researcher who later launched an AI-science startup, and at least seven researchers who were recruited by Meta.