Former OpenAI CTO Mira Murati built Thinking Machines into a $12 billion symbol of the AI boom, but a sudden wave of departures has turned her showcase lab into a case study in how fragile that success can be. Co-founders, senior scientists, and rising stars are streaming out to rivals just as the company chases ever higher valuations, exposing how brutal the competition for elite researchers has become. The stakes are not just Murati’s reputation or one startup’s future, but who controls the next generation of general purpose AI.
From breakout challenger to $12 billion lightning rod
When Former CTO Mira Murati left OpenAI to start Thinking Machines Lab, she did not tiptoe into the market, she escalated the fight for scarce researchers by recruiting top talent from incumbents and pitching a new kind of general purpose AI lab. Early reporting described how Thinking Machines Lab set out to reshape the landscape by pulling experienced engineers away from rivals that had spent years training them. That aggressive hiring spree quickly turned the company into a magnet for ambitious researchers who wanted to work with a Former OpenAI CTO on cutting edge models.
The momentum translated into eye watering numbers. Investors valued Mira Murati’s Thinking Machines at roughly $12 billion and, by late 2025, the company was in talks to push that even higher, with one report saying Mira Murati’s Thinking Machines sought a $50 billion valuation in funding talks. Another discussion of those negotiations framed the question bluntly, asking whether there was fundamental growth to justify a 50 billion price tag or whether investors were simply betting on Murati’s track record at the previous lab. That kind of scrutiny is the backdrop for what happened next.
The dam breaks: co-founders, researchers and a scandal
The first visible crack in Thinking Machines’ leadership came when Andrew Tulloch, described as another co-founder, chose to leave for Meta in late 2025 instead of staying to ride the valuation wave. One account framed Meta’s move as a Talent Play, highlighting a $1.5 billion figure to show how Hiring This Engineer Signals How Hot AI Has Become and What Pitfalls And Expectations Come With Such a Hire. Another analysis called Tulloch’s exit “the first crack” and noted that Andrew Tulloch leaving for Meta signaled that the very people who were supposed to be disrupting the incumbents were now being absorbed by them.
Then the departures accelerated. Earlier this week, reports surfaced that Thinking Machines co-founders were heading back to OpenAI, with one newsletter describing how OpenAI Lures Back 3 Top Researchers and how that reversal pulled Thinking Machines into a broader AI Talent Wars narrative. Another account emphasized that the news that Thinking Machines co-founders Barre and others were returning to their former employer should worry prospective investors who had just been asked to underwrite sky high valuations. At the same time, a separate report detailed how Thinking Machines Cofounder Office Relationship Preceded His Termination, with Thinking Machines Cofounder at the center of a workplace investigation that cited an office relationship and referenced 40 as part of the timeline in Maxwell Zeff’s Business coverage. That mix of voluntary exits and internal turmoil turned a leadership reshuffle into a full blown exodus.
Wave of defections and the pull of Big Tech gravity
By mid January, what had started as a few high profile moves had become a wave. One detailed account described a Wave of defections from former CTO Mira Murati’s $12 billion startup Thinking Machines, noting that the bombshell news underscored how hard it is for new labs dedicated to state of the art general purpose systems to hold on to their best people. That same report highlighted how, on Thursday, at least two additional Thinking Machines researchers, Lia Guy and Ian O’Connell, were reported to be leaving to join Meta’s AI efforts, showing that the talent drain was not limited to OpenAI. Another section of the coverage stressed that the bombshell news underscored the difficulties facing a new wave of AI labs that want to build general purpose systems while competing with giants for the same people, and it explicitly tied that challenge to the departures of Lia Guy and O’Connell.
Separate reporting drilled into the leadership structure that had made Thinking Machines so attractive in the first place. One piece described a Wave of defections from former CTO Mira Murati’s $12 billion startup Thinking Machines and explained how senior figures like Zoph, Metz and Schoenholz had been central to the lab’s research agenda. It noted that these leaders, including those who had been reporting to Zoph, were now part of the same story of departures that was reshaping the company. Another section of that coverage reiterated that the Wave of defections from former CTO Mira Murati’s $12 billion startup Thinking Machines was a vivid example of the cutthroat struggle for AI talent, and it detailed how the reporting line from Metz and Schoenholz to Zoph had been part of the lab’s pitch to investors. The fact that such a carefully assembled hierarchy could unravel so quickly illustrates just how strong the gravitational pull of incumbents like OpenAI and Meta has become.
Inside the $12 billion talent war
To understand why so many people are leaving, it helps to look at the broader market dynamics. One investor focused newsletter framed the current environment as AI Talent Wars a Wildcard for Founders & Investors as valuations soar, pointing to how Cursor Enters Talent Sweepstakes and how OpenAI Lures Back 3 Top Researchers from Thinking Machines co-founders such as Barre. That framing makes clear that Thinking Machines is not an isolated case but part of a pattern in which well funded incumbents and new entrants bid against each other for a small pool of people who can actually ship frontier models. Another analysis of the same trend argued that this kind of reversal, where co-founders return to their old employer, has got to worry prospective investors who are being asked to support valuations that assume stable leadership and a deep bench of researchers.
There is also a cultural and strategic dimension. One newsletter that tracks the sector noted that OpenAI, for its part, appears to be reeling from its own high profile departures, with internal concerns about the organisation’s culture and long term vision. That same digest suggested that the turbulence at OpenAI had created an opening for challengers like Thinking Machines, only for the momentum to swing back as OpenAI stabilized and began to reassert its pull. The report on those internal concerns at OpenAI underscores that even the giants are not immune to churn, but they have the brand, capital and infrastructure to keep drawing people back. In that context, a $12 billion startup that is still building its own culture has far less margin for error.
What the exodus means for founders, investors and the next wave of labs
For founders, the lesson is brutal. One LinkedIn analysis by Rubén Domínguez Ibar argued that Mira Murati’s Thinking Machines is losing its core team to OpenAI, listing how 3+ co-founders have rejoined OpenAI and how More early employees are following, and concluding that gravity is clearly concentrated around a few dominant labs. That same post warned that this validates the idea that overreliance on a single star founder can backfire, and it pointed to Murati’s own public comments, including a tweet about OpenAI, as a sign of how personal these battles have become. The observation that Mira Murati‘s Thinking Machines is losing its core team to OpenAI is not just gossip, it is a warning about how quickly momentum can shift when a company’s identity is tightly bound to one person.
More From The Daily Overview
Grant Mercer covers market dynamics, business trends, and the economic forces driving growth across industries. His analysis connects macro movements with real-world implications for investors, entrepreneurs, and professionals. Through his work at The Daily Overview, Grant helps readers understand how markets function and where opportunities may emerge.
