Lilian Weng, co-founder of Thinking Machines, announced this week she is stepping down from the startup, citing health concerns tied to the pace and stress of startup work. She said she had concluded over several months that the sustained workload had exceeded what her health could support.
OpenAI confirmed Wednesday that Weng, who previously served as the company’s VP of AI Safety Research, will be rejoining the organization. According to a company spokesperson, she will lead a top-level team focused on accelerating OpenAI’s internal research, supporting cross-research efforts on recursive self-improvement, a process aimed at allowing AI systems to iterate on themselves to become more capable.
The move stands in some tension with Weng’s stated reasons for leaving Thinking Machines, though her role at OpenAI, where she is not a co-founder, may carry less direct pressure than a startup leadership position. Her departure comes amid intense competition for AI talent across major labs.
Mira Murati, Thinking Machines co-founder and former OpenAI CTO, responded to Weng’s announcement by expressing support for her decision to prioritize her health, thanking her for her contributions to the company without indicating whether she was aware Weng would return to OpenAI.
