Lilian Weng Quits Thinking Machines for Health, Returns to OpenAI

Lilian Weng, co-founder of Thinking Machines (often called Thinky), announced her departure from the startup this week, citing health concerns. In an internal Slack message shared publicly, she wrote, "I don't feel I’m able to continue at the pace a startup requires" and noted that "the amount of consistent stress and workload have pushed me beyond what my health can sustain physically." The move signals the immense pressure faced by leaders in high-growth AI startups.

On Wednesday, OpenAI confirmed Weng will rejoin the company, where she previously served as VP of AI Safety Research. She will lead a top-level team accelerating internal research on recursive self-improvement—a process enabling AI systems to iterate on themselves to become more powerful. Mira Murati, former OpenAI CTO and a fellow Thinking Machines co-founder, replied to Weng's post with support: "We’ll miss you... I’m glad that you’re putting your health first." The turnaround underscores fierce talent competition in AI labs, though Weng's expanded role at OpenAI may involve less direct pressure than co-founding a startup.