Thinking Machines Lab cofounder Lillian Weng leaves to rejoin OpenAI

Lilian Weng, cofounder of Thinking Machines Lab and a former OpenAI safety leader, has left the startup for health reasons.

OpenAI says Weng is returning to the company to lead a team supporting research on recursive self-improvement.

The move highlights ongoing talent churn among top AI labs and OpenAI’s renewed emphasis on safety-adjacent research.