Lilian Weng said she didn't feel able to continue working at the "pace a startup requires."
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A cofounder of Thinking Machines Lab said she's stepping down because of stress and illness.Lilian 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.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. She did not disclose a specific diagnosis."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.She said the "amount of consistent stress and workload have pushed me beyond what my health can sustain physically."It 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. pic.twitter.com/VGb5fM5chX— Lilian Weng (@lilianweng) July 27, 2026
