After less than a year at Meta, the prominent AI researcher Andrew Tulloch is leaving for Anthropic.
He'll start next week, an Anthropic spokesperson told Business Insider, and work on the startup's inference and performance team, where he'll aim to optimize the training of Anthropic's AI models and how they respond to users.
As AI's talent wars steam on, Tulloch has become one of the most sought-after researchers. He had worked at Meta for 11 years prior to this latest stint, leaving for OpenAI in 2023. At OpenAI, he helped train its GPT-4o, GPT-4.5, and o3 models. He then cofounded Thinking Machines Lab in 2025.
Last year, while he was working at the AI startup, he turned down a pay offer from Meta CEO Mark Zuckerberg that could have totalled $1.5 billion, The Wall Street Journal reported. He ended up decamping for Meta in October.
Now, Tulloch will bring that extensive experience to Anthropic.
Tulloch and Meta did not immediately respond to requests for comment. He's leaving the social media giant shortly after it launched Muse, an AI agent meant to autonomously complete tasks for users.
Anthropic, Meta, OpenAI, Google, and other tech companies have been in a pitched battle for AI researchers since the release of ChatGPT, giving experienced workers like Tulloch a great deal of leverage — and earning power.
Semafor first reported that Tulloch was leaving Meta.
For Anthropic, the hire may offer some calm in an intense moment. The company is preparing for its initial public offering, dueling with rivals for business, and reckoning with mounting concerns about the adverse effects of AI. The researcher Jacob Coxon sparked a wave of concern this week when he announced that he'd resigned from Anthropic and wrote that the "people building AI earnestly believe that it could kill us all by the end of the decade."
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