OpenAI's chief executive for AGI development, Fidji Simo, is leaving the company for health reasons after less than a year in the role, the latest setback for a company navigating financial strain, IPO delays, and mounting signs that it is losing ground to rival Anthropic.

In a LinkedIn post announcing her departure, Simo — who had been on medical leave since April — said she had been living with a chronic illness diagnosed seven years ago. CNBC reported she has Postural Orthostatic Tachycardia Syndrome (POTS), a nervous system disorder that causes an abnormally rapid heart rate and dizziness upon standing. Before joining OpenAI, Simo had served as CEO of Instacart.

"It has been a jarring experience to spend my days helping build the future while simultaneously navigating a disabling disease that has no cure," she wrote. Simo said she would continue her health advocacy work with ChronicleBio and Complex Disorders Alliance and transition to a part-time advisory role at OpenAI.

Her departure extends a difficult stretch of executive attrition. In recent months, OpenAI has also lost Chief Futurist Joshua Achiam, Chief Product Officer Kevin Weil, Vice President of Engineering Srinivas Narayanan, and Bill Peebles, the senior researcher who led the development of Sora.

OpenAI's Challenges Mount

The leadership instability comes as OpenAI faces pressure on multiple fronts.

On the competitive front, Anthropic has pulled ahead, based on the most recently disclosed metrics. In April, Anthropic reported it had tripled its annualized revenue run rate to $30 billion, surpassing OpenAI's roughly $24 billion. is now valued at $1.08 trillion, above 's private market valuation of $864.6 billion, according to Nasdaq Private Market data.

Both companies confidentially filed for IPOs last month without disclosing offering sizes. Reports have since emerged that OpenAI is likely to delay its listing until next year, pushing past earlier expectations that both companies would debut in the fourth quarter of 2026.

OpenAI's financials are drawing intense scrutiny. The Financial Times reported last month that the company's net loss ballooned from $5 billion in 2024 to $39 billion last year, as it continued to spend heavily on model development and compute capacity.

Meanwhile, one of OpenAI's biggest backers, SoftBank, is reportedly struggling to raise a $6 billion margin loan after lenders gave a lukewarm response to the proposed collateral — its stake in OpenAI.

On the product side, OpenAI is shutting down Altas, an AI web browser announced in October, as part of an effort to reduce what it internally calls "side quests" and refocus on catching up with Anthropic on productivity features, The Verge reported Thursday.

On Stocktwits, retail sentiment was 'bearish' for both OpenAI and Anthropic.