Fidji Simo, OpenAI’s second-in-command and CEO of Applications, is leaving her full-time role after a difficult medical leave. She’ll transition to a part-time advisory role. Simo joined just last year from Instacart, where she’d been CEO, and previously spent over a decade at Meta. Her departure leaves CEO Sam Altman scrambling for a successor at a critical time — OpenAI is eyeing an IPO and racing to catch up to Anthropic in enterprise coding tools. Simo was tasked with growing ChatGPT’s consumer business, but growth cooled late last year and missed internal revenue targets. Meanwhile, the executive bench looks thin for a company valued at $852 billion. Why it matters: With key leaders gone and a possible IPO looming, Altman faces the challenge of stabilizing management while keeping OpenAI competitive in both consumer and enterprise AI.