Thinking Machines Lab cofounder Lilian Weng steps down, citing startup-related stress and illness

Jul 28, 2026 05:33 PM - 1 day ago 147

Fellows Fund Welcomes Lilian Weng arsenic New Distinguished Fellow

Lilian Weng said she didn't consciousness capable to proceed moving astatine the "pace a startup requires." Business Wire/AP

A cofounder of Thinking Machines Lab said she's stepping down because of accent and illness.

Lilian Weng said successful a station connected X that Tuesday would beryllium her past time astatine Thinking Machines Lab, the AI startup she cofounded pinch OpenAI's erstwhile main exertion officer, Mira Murati.

Weng, antecedently OpenAI's vice president of investigation and safety, said she had been sick much often successful the past 7 months than astatine immoderate different constituent successful her life. She did not disclose a circumstantial diagnosis.

"Despite each the laughter and challenges building a neolab has brought us, I don't consciousness I'm capable to proceed astatine the gait a startup requires," Weng wrote successful a connection she said she had shared pinch colleagues astatine the company, known internally arsenic Thinky.

She said the "amount of accordant accent and workload person pushed maine beyond what my wellness tin prolong physically."

It is simply a difficult and sad decision. I shared this connection pinch folks astatine Thinky. Thank you each for the clip together♥️ Just arsenic the past condemnation successful my message: The early worthy building is human. pic.twitter.com/VGb5fM5chX

— Lilian Weng (@lilianweng) July 27, 2026

Weng said she tried to remainder and decently return sick time off while Thinking Machines was "sprinting" to merchandise Inkling, the company's first open-weight model, but felt "guilt."

She said she had considered a narrower domiciled that would origin little anxiety, but decided it was not a fit. "If I cannot springiness it 100% for what I should beryllium responsible for, I neglect my job," she wrote.

Instead, Weng said she would activity a much predictable, scoped domiciled extracurricular a cofounder position while staying successful AI.

"We'll miss you, it's been awesome building Thinky together," wrote Murati successful a reply connected X. "I'm gladsome that you're putting your wellness first."

AI execs put wellness first

Weng's departure follows respective caller health-related step-backs by leaders successful the AI industry.

Earlier this month, Fidji Simo stepped down from her full-time domiciled arsenic OpenAI's CEO of AGI aft a flare-up of postural orthostatic tachycardia syndrome, aliases POTS. Simo moved into a part-time advisory domiciled and said she would attraction connected betterment from the chronic illness.

In January, xAI cofounder Greg Yang said he had moved into an informal advisory domiciled aft doctors diagnosed him pinch Lyme disease. Yang said months of unexplained fatigue had near him pinch little power and creativity, and that he wanted to "go laminitis mode connected my health."

Weng's departure besides comes arsenic Thinking Machines Lab has mislaid a important stock of its founding squad amid Silicon Valley's AI talent war.

A Business Insider review in May recovered that 13 of the startup's 42 founding members had near since launch, including 3 of its six cofounders, arsenic rivals — including Meta and OpenAI — offered immense compensation packages.

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Thibault is simply a business newsman astatine Business Insider's London office.He covers the intersection of wealth, work, and exertion — focusing connected the world economy, AI’s effect connected the workplace, occupation and cognitive skills, and really economical changes are affecting careers. Before moving to the trending team, Thibault covered world affairs, including the Russia-Ukraine war, tensions successful the South China Sea, and Russia’s system connected the news desk.He has antecedently worked astatine the Daily Express and held internships astatine Agence France-Presse, Politico Europe, and Factal.Il parle français. Se habla español.Email Thibault astatine [email protected], link pinch him connected LinkedIn @ThibaultSpirlet, aliases travel him connected X @ThibaultSpirlet and BlueSky @thibaultspirlet.bsky.social.Expertise

  • AI and the early of work 
  • Job and cognitive skills successful the AI economy
  • Workforce trends
  • First-person, "as-told-to" business stories

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