• Joshua Gross, a top engineer at Thinking Machines Lab, has rejoined Meta.
• It's the latest in a string of departures from the $12 billion startup's founding team.
• Thinking Machines continues to attract star AI talent and has more than quadrupled its size.

Thinking Machines Lab, the startup founded by ex-OpenAI CTO Mira Murati, has lost another founding member to Meta.

A veteran software engineer, Joshua Gross, built and shipped Thinking Machines Lab's flagship product, Tinker, from "zero-to-one," according to his LinkedIn profile.

He joined Meta Superintelligence Labs last month and now leads engineering teams, according to his LinkedIn profile. Gross had previously worked at OpenAI and Meta (formerly Facebook).

Thinking Machines Lab, which raised a huge $2 billion funding round at a $12 billion valuation last year, has become an AI talent hub. It has faced a wave of poaching from larger tech companies as Silicon Valley's AI talent wars grow hotter than ever.

Meta has now hired five of its founding members, including cofounder Andrew Tulloch. Meanwhile, OpenAI hired the startup's ex-CTO, Barret Zoph, and a top cybersecurity employee, Jolene Parish.

Thinking Machines Lab has had notable wins of its own. It replaced its CTO with Meta's Soumith Chintala, the creator of the open-source AI project PyTorch, and it quietly hired Neal Wu, a coder who won three gold medals in an Olympiad for programming, Business Insider previously reported.

The startup, which is based in San Francisco, has more than quadrupled in size to about 130 staffers since its founding last year, according to a person familiar with the matter.

Meta and Thinking Machines Lab declined to comment.

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