Thinking Machines Lab Loses Two Co-Founders to OpenAI Return

Two co-founders of Thinking Machines Lab, the AI startup led by former OpenAI executive Mira Murati, have left to return to OpenAI. The moves happened this week and involve Barret Zoph, the company's chief technology officer, and Luke Metz, another key early team member. A third person, Sam Schoenholz, is also heading back to OpenAI from the startup. These changes took place in San Francisco, where both companies operate, and follow several weeks of planning, according to people familiar with the matter.

Background

Mira Murati spent years at OpenAI, rising to chief technology officer. She stepped in as interim CEO in late 2023 after the board removed Sam Altman from that role. Altman returned soon after, but Murati left OpenAI in September 2024 to start her own company. She gathered a team of researchers and engineers from OpenAI, Google, Meta, and other places to form Thinking Machines Lab in February 2025.

The startup started small with about 30 people but grew fast. It raised $2 billion in seed funding within five months, putting its value at $12 billion. Investors included Andreessen Horowitz, Accel, Nvidia, AMD, and Jane Street. That made it one of the biggest seed rounds ever in Silicon Valley. Murati set up the company as a public benefit corporation, similar to OpenAI and Anthropic. She holds more voting power than the rest of the board, which gives her strong say over decisions.

Thinking Machines Lab focuses on making AI systems that work well with people in different jobs. The team wants to build models that teams can adjust for their own needs. They study ways to improve AI without needing huge amounts of computer power. For example, they look at techniques like Low-Rank Adaptation, or LoRA, which lets people tweak models cheaply by changing only small parts instead of everything.

In October 2025, the company put out its first product called Tinker. This tool helps developers customize open-source AI models from companies like Meta, Alibaba, and others. Tinker handles the hard parts of fine-tuning, like managing costs and computer setups. The startup has shared some of its research papers on topics like better GPU use and model training methods. They plan to release their own AI models in 2026 and add features to Tinker, such as handling images and video alongside text.

People in the AI world watched Thinking Machines Lab closely last year. It stayed quiet at first, building a team of top experts. John Schulman, who co-founded OpenAI and later worked at Anthropic, joined as chief scientist. Other early members included researchers like Andrew Tulloch and Lilian Weng from OpenAI days. The company talked about sharing knowledge to help more people use AI safely and effectively.

Key Details

The departures came to light on Wednesday through posts on X, the social media site. Murati posted first about Zoph leaving. Zoph had been CTO at Thinking Machines Lab. Before that, he was vice president of research at OpenAI and spent six years at Google as a research scientist.

“We have parted ways with Barret,” Murati wrote. “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 excited to have him take on this new responsibility.” – Mira Murati, CEO of Thinking Machines Lab

Chintala comes from Meta, where he helped build early deep learning tools. He joined Thinking Machines Lab and now steps into the top tech role.

Just over an hour later, Fidji Simo, OpenAI's CEO of applications, posted about the hires. She named Zoph, Metz, and Schoenholz as the new team members. Metz co-founded Thinking Machines Lab and worked on technical staff at OpenAI for years. Schoenholz also has an OpenAI background, and his profile still showed him at the startup until recently.

These are not the first losses for Thinking Machines Lab. Andrew Tulloch, another co-founder, left in October to join Meta. Such moves happen often in AI, where experts jump between labs. OpenAI has seen its own founders leave to start rivals or join them, like Schulman who went to Anthropic before landing at Thinking Machines.

Timeline of Key Events

• February 2025: Thinking Machines Lab launches with Murati, Zoph, Metz, and others.
• July 2025: Raises $2 billion seed round.
• October 2025: Releases Tinker product; Tulloch leaves for Meta.
• November 2025: Seeks $5 billion more funding at $50 billion value.
• January 2026: Zoph, Metz, and Schoenholz depart for OpenAI.

The startup keeps growing its research. It plans multimodal tools in Tinker and easier ways for non-experts to customize AI. As of late last year, the team aimed to broaden access beyond just top labs.

What This Means

Losing co-founders so soon after starting raises questions about team stability at Thinking Machines Lab. Zoph's role as CTO meant he shaped tech direction, and Metz brought deep OpenAI know-how. Their return to OpenAI strengthens the bigger company, which already leads in AI products like ChatGPT. OpenAI gains back familiar faces who know its systems well.

For Thinking Machines Lab, Chintala's appointment brings fresh experience from Meta's AI work. The company still has Murati at the helm, Schulman as chief scientist, and a roster of experts. Its funding and first product give it a base to build on. But holding onto talent will matter in a field where people move fast.

The AI sector sees these shifts all the time. Labs compete for the best minds to push models forward. Thinking Machines Lab carved a spot with efficient training methods, different from rivals chasing ever-bigger systems. Tinker targets developers needing custom AI without big budgets. Plans for 2026 models could help it stand out.

OpenAI's hires fit its pattern of pulling in experts. Simo called the moves exciting, noting they planned for weeks. This back-and-forth shows how connected the industry is. Startups like Thinking Machines draw from giants, then sometimes send people back.

Broader effects touch funding and competition. Thinking Machines seeks more money soon. Investors watch leadership changes closely. If the company delivers on Tinker updates and new models, it could keep momentum. Meanwhile, OpenAI bolsters its team amid its own growth.

Talent flow shapes AI progress. When experts like Zoph and Metz move, they carry ideas across companies. This can speed up innovation but also spark worries about concentrated power. Thinking Machines Lab stressed open research to counter that. Its next steps, like product upgrades and hires, will show how it handles this shake-up.