{"slug": "thinking-machines-lab-cofounder-lilian-weng-steps-down-citing-startup-related", "title": "Thinking Machines Lab cofounder Lilian Weng steps down, citing startup-related stress and illness", "summary": "Lilian Weng, cofounder of Thinking Machines Lab, announced her departure from the AI startup on Tuesday, citing stress and illness that left her unable to sustain the pace required by a startup. Weng, previously OpenAI's vice president of research and safety, said she had been ill more often in the past seven months than at any other point in her life and will seek a more predictable role outside a cofounder position while staying in AI.", "body_md": "A cofounder of [Thinking Machines Lab](https://www.businessinsider.com/mira-murati-new-ai-startup-thinking-machines-funding-2025-4) said she's stepping down because of stress and illness.\n\nLilian Weng said in a post on X that Tuesday would be her last day at Thinking Machines Lab, the AI startup she cofounded with OpenAI's former chief technology officer, [Mira Murati](https://www.businessinsider.com/thinking-machines-lab-key-talent-meta-openai-xai-2026-5).\n\nWeng, previously OpenAI's vice president of research and safety, said she had been ill more often in the past seven months than at any other point in her life. She did not disclose a specific diagnosis.\n\n\"Despite all the laughter and challenges building a neolab has brought us, I don't feel I'm able to continue at the pace a startup requires,\" Weng wrote in a message she said she had shared with colleagues at the company, known internally as Thinky.\n\nShe said the \"amount of consistent stress and workload have pushed me beyond what my health can sustain physically.\"\n\nIt is a hard and sad decision. I shared this message with folks at Thinky. Thank you all for the time together♥️ Just as the last sentence in my message: The future worth building is human.\n\n— Lilian Weng (@lilianweng)[pic.twitter.com/VGb5fM5chX][July 27, 2026]\n\nWeng said she tried to rest and properly take sick leave while Thinking Machines was \"sprinting\" to release Inkling, the company's first [open-weight model](https://www.businessinsider.com/anthropic-open-source-ai-model-weights-criticism-2026-7), but felt \"guilt.\"\n\nShe said she had considered a narrower role that would cause less anxiety, but decided it was not a fit. \"If I cannot give it 100% for what I should be responsible for, I fail my job,\" she wrote.\n\nInstead, Weng said she would seek a more predictable, scoped role outside a cofounder position while staying in AI.\n\n\"We'll miss you, it's been wonderful building Thinky together,\" wrote Murati in a reply on X. \"I'm glad that you're putting your health first.\"\n\n## AI execs put health first\n\nWeng's departure follows several recent health-related step-backs by leaders in the AI industry.\n\nEarlier this month, [Fidji Simo](https://www.businessinsider.com/fidji-simo-pots-symptoms-openai-medical-leave-zuckerberg-health-advice-2026-7) stepped down from her full-time role as OpenAI's CEO of AGI after a flare-up of postural orthostatic tachycardia syndrome, or POTS. Simo moved into a part-time advisory role and said she would focus on recovery from the chronic illness.\n\nIn January, [xAI cofounder Greg Yang](https://www.businessinsider.com/xai-cofounder-lyme-disease-advisory-founder-mode-greg-yang-2026-1) said he had moved into an informal advisory role after doctors diagnosed him with Lyme disease. Yang said months of unexplained fatigue had left him with less energy and creativity, and that he wanted to \"go founder mode on my health.\"\n\nWeng's departure also comes as Thinking Machines Lab has lost a significant share of its founding team amid Silicon Valley's AI talent war.\n\nA [Business Insider review](https://www.businessinsider.com/thinking-machines-lab-key-talent-meta-openai-xai-2026-5) in May found that 13 of the startup's 42 founding members had left since launch, including three of its six cofounders, as rivals — including Meta and OpenAI — offered huge compensation packages.", "url": "https://wpnews.pro/news/thinking-machines-lab-cofounder-lilian-weng-steps-down-citing-startup-related", "canonical_source": "https://www.businessinsider.com/thinking-machines-lab-cofounder-lilian-weng-steps-down-stress-illness-2026-7", "published_at": "2026-07-28 10:33:36+00:00", "updated_at": "2026-07-28 10:57:50.294560+00:00", "lang": "en", "topics": ["artificial-intelligence", "ai-startups", "ai-safety"], "entities": ["Lilian Weng", "Thinking Machines Lab", "Mira Murati", "OpenAI", "Inkling", "Fidji Simo", "Greg Yang", "xAI"], "alternates": {"html": "https://wpnews.pro/news/thinking-machines-lab-cofounder-lilian-weng-steps-down-citing-startup-related", "markdown": "https://wpnews.pro/news/thinking-machines-lab-cofounder-lilian-weng-steps-down-citing-startup-related.md", "text": "https://wpnews.pro/news/thinking-machines-lab-cofounder-lilian-weng-steps-down-citing-startup-related.txt", "jsonld": "https://wpnews.pro/news/thinking-machines-lab-cofounder-lilian-weng-steps-down-citing-startup-related.jsonld"}}