Mira Murati became a well-known figure in the tech industry during her time as CTO of OpenAI, where she played a key role in delivering products such as ChatGPT, DALL·E, and other popular AI offerings.
She also played a pivotal role during OpenAI’s 2023–2024 boardroom turmoil. According to court documents, Murati was a core source of key technical evidence that informed the board’s decision to temporarily remove Sam Altman as CEO. During the crisis, she served as interim CEO. Later, when the majority of OpenAI employees publicly rallied behind Altman, Murati also expressed her support for him.
In late 2024, Murati left OpenAI along with several senior executives, including Bob McGrew and Barret Zoph. In February 2025, she founded Thinking Machines Lab with a group of prominent AI researchers, including John Schulman, Barret Zoph, Lilian Weng, Andrew Tulloch, and Luke Metz. Within its first five months, Thinking Machines Lab reportedly raised $2 billion, even before releasing a product.
Last year, Andrew Tulloch, one of the co-founders of Thinking Machines Lab and its Chief Architect, left the startup to join Meta Platforms. Today, Barret Zoph, CTO of Thinking Machines Lab, announced that he is returning to OpenAI. Along with Zoph, Luke Metz and Sam Schoenholz are also leaving the startup to join OpenAI.
Over the past year, OpenAI has primarily seen high-profile departures, making the return of Zoph and others a surprising development. Fidji Simo, OpenAI’s CEO of Applications, confirmed the news on X, stating she is excited to welcome Barret Zoph, Luke Metz, and Sam Schoenholz back to the company. Zoph will report to Simo, while Metz and Schoenholz will report to Zoph. Simo added that more details about their roles will be shared in the coming months.
Thinking Machines Lab CEO Mira Murati also commented on Zoph’s departure in a post on X.
We have parted ways with Barret Zoph.
— Mira Murati (@miramurati) January 14, 2026
Soumith Chintala will be the new CTO of Thinking Machines. He is a brilliant and seasoned leader who has made important contributions to the AI field for over a decade, and he’s been a major contributor to our team. We could not be more…
Among the key founders of Thinking Machines Lab, only Chief Scientist John Schulman remains at the startup. It remains to be seen whether he will continue at the company following the departure of several core team members.