Fidji Simo is stepping down after taking medical leave because of a worsening chronic illness. The big picture: Simo's departure removes one of OpenAI's highest-profile executives. Driving the news: Simo said Thursday she is stepping down as OpenAI's head of product and business after a "severe exacerbation" of Postural Orthostatic Tachycardia Syndrome (POTS), a chronic condition she was diagnosed with in 2019. She went on medical leave in April, and OpenAI President Greg Brockman assumed resp