Lilian Weng Leaves Thinking Machines Lab Due to Health Issues
Lilian Weng, co-founder of Thinking Machines Lab (Thinky), announced her departure on July 28, stating that the next day would be her last. She attributed the decision to deteriorating health: repeated illness over the past 7 months, with constant stress and startup pace exceeding her physical limits, making it impossible to continue the high-intensity co-founder role. CEO Mira Murati publicly confirmed and thanked her.
Confirmed
- Lilian Weng described it as a difficult and sad decision. She still loves AI and cutting-edge research but needs a more predictable, less intense role than co-founder.
- She felt guilty for not being able to work at full capacity and ended her farewell message emphasizing a human-centric future.
- Mira Murati said building the company with Weng was a precious experience and supported her prioritizing health.
- Multiple media posts noted that Weng worked at OpenAI for nearly 7 years, leading a safety systems team of over 80 people; her departure is seen as a signal of organizational stability in AI startups.
- Chuangyebang reported that four of the six co-founders of Thinking Machines have left.
- Kuaileyu reported the company was founded only 20 months ago.
Unconfirmed
- A single post mentioned changes involving Chenglei Si, but no details were provided; this remains unconfirmed.
Why it matters
- This is a formal departure of a key early member of Thinky, quickly drawing community attention.
- Anshul Kundaje's retweet suggested a broader trend: the AI industry may see companies with high technical ambition but more sustainable work rhythms.
2026-07-28 ~ 2026-07-28 · 16 related posts
Primary sources
- [source] Thinky staffer Lilian says she is leaving after seven hard months — lilianweng · 2026-07-28
- Lilian Weng Departs OpenAI: 'The Future Worth Building is Human' — brhydon · 2026-07-28
- Thinky farewell post signals a personnel change around Lilian Weng and Chenglei Si — YifeiZhou02 · 2026-07-28
- Lilian Weng hints at a hard, sad decision and says the future worth building is human — jachiam0 · 2026-07-28
- [source] Mira Murati says Lilian Weng is leaving Thinky to prioritize her health — miramurati · 2026-07-28
- Ex-OpenAI Research Chief Lilian Weng Departs Thinking Machines Lab — MuCai7 · 2026-07-28
- Lilian Weng Leaves Thinking Machines Citing Health Reasons — APPSO · 2026-07-28
- [source] Thinking Machines Lab cofounder Lilian Weng leaves after seven months of illness — 机器之心 · 2026-07-28
- Lilian Weng leaves Thinking Machines due to illness — 新智元 · 2026-07-28
- Lilian Weng’s Thinky departure sparks a case for slower AI companies — anshulkundaje · 2026-07-28
- Thinking Machines Lab co-founder Lilian Weng exits after 20 months and first model launch — 快鲤鱼 · 2026-07-28
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