Lilian Weng leaves Thinking Machines after seven months of illness

量子位 · wechat · 2026-07-28

Lilian Weng leaves Thinking Machines after seven months of illness

Lilian Weng, former OpenAI safety VP and cofounder of Thinking Machines, says tomorrow will be her last day at the company. In her note, she says she has been dealing with severe illness for the past seven months and that the pace and intensity of the work made it impossible to keep going at full capacity.

She says she briefly considered taking a narrower role, but did not want to work at less than 100% on the responsibilities she owned. She also says she still loves AI, still wants to read papers and follow the frontier, but wants a more predictable role with clearer boundaries.

The post also places her exit in the context of Thinking Machines’ volatile year: Mira Murati founded the company in early 2025 with a mostly ex-OpenAI team, the company raised a $2 billion seed round at a $12 billion valuation, launched its first open model Inkling, and then saw multiple cofounders and key people leave over time. In that timeline, Weng’s departure is another sign of how much strain the company has been under.

Related event: Lilian Weng Leaves Thinking Machines Lab Due to Health Issues(16 posts)→

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