Thinking Machines Lab is losing senior staff.
OpenAI has brought back Brett Zoph, who until recently was the startup’s chief technology officer. Two researchers, Luke Metz and Sam Schoenholz, are also returning to the company. All three had worked at OpenAI earlier in their careers.
The hires were acknowledged on January 14 by Fidji Simo, who oversees applications at OpenAI. Zoph is expected to report to her. Metz and Schoenholz will work under Zoph.
Around the same time, other departures were reported at Thinking Machines Lab. Lia Guy is expected to join OpenAI. Ian O’Connell is also leaving the startup, though details about his next role remain unclear.
Before the hires were made public, Mira Murati told staff that Zoph’s employment had been terminated. The message referenced concerns around conduct. OpenAI disputes that account.
In a separate internal message, Simo told employees that discussions with Zoph and the other researchers had been underway for weeks. She said OpenAI did not share the concerns raised by Thinking Machines Lab and had reviewed the matter internally before moving forward. According to the message, Zoph had already indicated he was considering leaving before his role ended.
The episode reflects how competitive the market for experienced AI researchers has become. New labs have raised large sums and announced ambitious goals, but retention remains fragile.
Large technology companies continue to offer compensation that startups struggle to match. In some recent cases, senior researchers have been offered packages worth more than $100 million, much of it paid in cash rather than equity.
About Thinking Machines Lab
Murati was a senior leader at OpenAI and played a role in the development of ChatGPT before leaving in 2024. She later launched Thinking Machines Lab with a focus on open research.
The startup released its first product in October 2025. The tool, called Tinker, allows developers to fine-tune language models using Python workflows that run on the company’s GPU infrastructure. The platform manages scheduling and system failures internally.
Thinking Machines Lab raised $2 billion in seed funding in 2025, valuing the company at $12 billion. Talks around a larger funding round were held later, though no announcement followed.
Staff movement has continued. One of the company’s cofounders left last year to join Meta.
For newer AI labs, the challenge is becoming clear. Funding helps. Vision helps. But when larger players decide to move, holding on to people is harder.
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