Lilian Weng, due to health reasons, has resigned from Thinking Machines Lab and returned to OpenAI

July 30th, Thinking Machines Lab co-founder Lilian Weng announced her resignation due to health reasons (having been ill repeatedly over the past seven months and facing excessive entrepreneurial stress), only to rejoin OpenAI a few days later.

She will lead a team focusing on "recursive self-improvement" research. This direction is a topic she has recently delved into on her blog, aiming to leverage AI to develop more powerful systems.

Weng Lillian previously served as Vice President of Security Research at OpenAI and head of the Applied AI Research team, co-founding Thinking Machines Lab in early 2025 with former OpenAI CTO Mira Murati, among others. This rapid return highlights the flow of top AI talent between high-intensity cutting-edge laboratories.