Lilian Weng Resigns From Thinking Machines Lab To Rejoin OpenAI For AI Research

Thinking Machines Lab co-founder Lilian Weng steps down citing health reasons and returns to OpenAI. She will lead a team focused on recursive self-improvement research, marking a rapid shift in top AI talent.

Woofun AI reports that Thinking Machines Lab co-founder Lilian Weng has resigned from the organization due to health reasons, citing repeated illness over the past seven months and excessive entrepreneurial stress. She subsequently rejoined OpenAI to lead a team dedicated to "recursive self-improvement" research, a topic she has recently explored on her blog with the aim of leveraging AI to develop more powerful systems. Weng previously served as Vice President of Security Research at OpenAI and head of the Applied AI Research team before co-founding Thinking Machines Lab in early 2025 alongside former OpenAI CTO Mira Murati.