Two narratives are already forming about what led to the departures. The news was first reported on X by technology reporter Kylie Robison, who wrote that Zoff was fired for “unethical conduct.”
A source close to Thinking Machines alleged that Zoff had shared confidential company information with competitors. WIRED was unable to verify this information with Zoff, who did not immediately respond to WIRED’s request for comment.
According to Simo’s memo, Zoff told Thinking Machines CEO Mira Muratti on Monday that he was considering leaving. After this, he was removed from the job on Wednesday. Simo further wrote that OpenAI does not share Murati’s concerns about Zoff.
The personnel change is a major win for OpenAI, which recently lost its vice president of research, Jerry Tworek. A third Thinking Machines employee, Sam Schonholz, is also rejoining OpenAI, according to the company’s announcement.
The departures are a blow to Thinking Machines, which also lost another co-founder, Andrew Tulloch, in November when he took a new job at Meta. In a post on X, Murati confirmed Zoff’s departure and said that Soumith Chintala will replace him as the startup’s Chief Technology Officer.
Zoff and Metz left OpenAI in late 2024 to start Thinking Machines with Murati, the former chief technology officer of the ChatGPIT maker. Zoff was previously OpenAI’s Vice President of Post-Training, where he led teams that made final improvements to AI models before they were deployed in products like ChatGPT and OpenAI’s API. Metz worked at OpenAI for two years during his first stint at the company, contributing to projects such as ChatGPT and the O1 AI reasoning model.
Simo told staff in his memo that Zoff would report directly to him, and Metz and Schoenholz would work under him. The appointment announcement timeline has been accelerated, he said, so they still have to work out some details about their roles.
Thinking Machines Lab is one of several well-funded AI startups led by former top OpenAI researchers, reflecting the incredible appetite among investors to capitalize on the AI race. Last year, Murati’s startup was valued at $12 billion, and was recently in talks to raise more than $4 billion at a valuation of $50 billion. The startup’s main product today is called Tkinter, which allows developers to customize AI models on their datasets.
<a href