Lilian Weng left Thinking Machines citing health, then rejoined OpenAI

Thinking Machines co-founder Lilian Weng left the company citing health reasons, then joined OpenAI

Lilian Weng stepped down as Thinking Machines co-founder this week, saying startup stress exceeded what her health could sustain. OpenAI confirmed Wednesday she is rejoining—she was previously VP of AI Safety Research—to lead a team focused on accelerating internal research, including recursive self-improvement. Mira Murati publicly supported Weng's health-first decision; the post doesn't say whether Murati knew she'd return to OpenAI.

Why it matters: Lilian Weng's rapid bounce from Thinking Machines back to OpenAI is the most dramatic talent move this week. TechCrunch confirmed her new role leading recursive self-improvement research, which adds strategic weight beyond a simple personnel change. Score held at 82 because it...