{"slug": "lilian-weng-flips-from-thinking-machines-to-openai-after-saying-the-startup-s", "title": "Lilian Weng flips from Thinking Machines to OpenAI after saying the startup's pace hurt her health", "summary": "Lilian Weng, a cofounder of Thinking Machines Lab who stepped down this week citing health concerns from the startup's pace, is rejoining OpenAI to lead a team focused on accelerating internal research for recursive self-improvement. The researcher, who previously worked at OpenAI from 2018 to 2024 and helped develop GPT-4, will return to the ChatGPT maker as part of its bid to develop AI that can improve itself, a company spokesperson told Business Insider.", "body_md": "[Lilian Weng](https://www.businessinsider.com/thinking-machines-lab-cofounder-lilian-weng-steps-down-stress-illness-2026-7), a cofounder of the AI startup Thinking Machines Lab who stepped down this week, is rejoining OpenAI.\n\nThe researcher will lead a team focused on accelerating internal research at the ChatGPT maker, as part of OpenAI's bid to develop AI that can improve itself, a company spokesperson told Business Insider.\n\nWeng had shared on Monday that she would be [leaving Thinking Machines](https://www.businessinsider.com/lilian-weng-thinking-machines-lab-exit-burnout-smart-people-reactions-2026-7) after a grueling stretch at the startup, writing, \"I don't feel I'm able to continue at the pace a startup requires.\"\n\n\"It has been an extremely hard decision, as I hate myself to let down people at Thinky but at the same time I'm constantly worried about my health,\" she added, referring to the startup's nickname.\n\nWeng wrote that she still enjoys working in the field and reading papers about frontier AI progress, saying that a \"scoped role in a more predictable place, and not as a cofounder\" would [suit her better](https://www.businessinsider.com/ai-tech-executive-health-stress-burnout-illness-lilian-weng-2026-7).\n\nThat role will now be at [OpenAI, the company](https://www.businessinsider.com/ai-singularity-experts-disagree-sam-altman-2026-7) where Weng worked from 2018 until late 2024, after stints at Facebook, Dropbox, and Affirm. During her first tenure at OpenAI, she helped build the Applied AI Research team and later led its Safety Systems work.\n\nWeng and Thinking Machines Lab didn't immediately respond to requests for comment.\n\nPreviously, Weng helped develop OpenAI's GPT-4 model, working on pretraining data, model safety, evaluations, and deployment.\n\nUpon her return, Weng will lead a team supporting [OpenAI's high-stakes effort](https://www.businessinsider.com/openai-sam-altman-ai-authoritarianism-open-source-export-controls-anthropic-2026-7) to achieve \"[recursive self-improvement](https://www.businessinsider.com/openai-safety-team-ai-self-improvement-challenge-job-2026-5),\" in which AI models can train and improve their successors.\n\nThe OpenAI spokesperson praised Weng's combination of research experience, technical know-how, and skill in building teams.\n\nFor [Thinking Machines Lab](https://www.businessinsider.com/thinking-machines-lab-key-talent-meta-openai-xai-2026-5), Weng's departure is the latest of many. Business Insider, in May, reported that nearly a third of the company's original founding members had left the startup since it launched.\n\nOf the startup's six cofounders, only two remain: Mira Murati, the CEO, and chief scientist John Schulman. Barret Zoph and Luke Metz left for OpenAI, while Andrew Tulloch left for Meta. Zoph left OpenAI in June, The Verge [reported](https://www.theverge.com/ai-artificial-intelligence/952837/barret-zoph-openai-thinking-machines-lab).\n\n[Mira Murati](https://www.businessinsider.com/mira-murati-openai-startup-2025-4), the former OpenAI CTO who leads the startup, thanked Weng for her service on X after she announced her departure on Monday.\n\n\"We'll miss you, it's been wonderful building Thinky together,\" Murati wrote. \"I'm glad that you're putting your health first. Thank you for everything.\"\n\n*Have a tip? Contact this reporter via email at *__scouncil@businessinsider.com__*, or over text, Signal, Telegram, or WhatsApp at 415-757-8198. Use a personal email address, a nonwork WiFi network, and a nonwork device; **here's our guide** to sharing information securely.*", "url": "https://wpnews.pro/news/lilian-weng-flips-from-thinking-machines-to-openai-after-saying-the-startup-s", "canonical_source": "https://www.businessinsider.com/lilian-weng-returns-to-openai-after-leaving-thinking-machines-lab-2026-7", "published_at": "2026-07-29 18:57:58+00:00", "updated_at": "2026-07-29 19:29:47.157364+00:00", "lang": "en", "topics": ["artificial-intelligence", "ai-research", "ai-startups", "ai-safety"], "entities": ["Lilian Weng", "Thinking Machines Lab", "OpenAI", "Mira Murati", "John Schulman", "Barret Zoph", "Luke Metz", "Andrew Tulloch"], "alternates": {"html": "https://wpnews.pro/news/lilian-weng-flips-from-thinking-machines-to-openai-after-saying-the-startup-s", "markdown": "https://wpnews.pro/news/lilian-weng-flips-from-thinking-machines-to-openai-after-saying-the-startup-s.md", "text": "https://wpnews.pro/news/lilian-weng-flips-from-thinking-machines-to-openai-after-saying-the-startup-s.txt", "jsonld": "https://wpnews.pro/news/lilian-weng-flips-from-thinking-machines-to-openai-after-saying-the-startup-s.jsonld"}}