Andrej Karpathy announced on May 19 that he has joined Anthropic, where he is reporting to pre-training team lead Nick Joseph. Karpathy was a founding member of OpenAI in 2015, ran Tesla's autonomy work for five years, returned to OpenAI for a year, and then left in 2024 to start Eureka Labs, an education-focused AI venture. According to multiple reports, he will spin up a sub-team focused on using Claude to accelerate pre-training research itself.
Pre-training is the most expensive and least public part of building a frontier model — the long compute runs that determine what a model knows before any fine-tuning or alignment work begins. Putting a researcher of Karpathy's profile inside that work, rather than on post-training or product, signals that Anthropic is investing in the foundational stack rather than only the safety and deployment layers it is best known for.
The move continues a pattern of senior researchers leaving OpenAI for rivals — Anthropic in particular — over the last two years, often citing differences over safety practices, commercialization speed, or research culture. Anthropic has used that talent inflow alongside its recent capital raises and compute deals to position itself as a credible peer to OpenAI on capabilities rather than a smaller safety-first alternative.
For learners watching the field: where senior researchers go is a more honest signal than benchmark numbers. Benchmarks can be gamed and marketing decks oversell, but a researcher with Karpathy's track record choosing a specific team to join is a vote about where the interesting unsolved problems are. Right now, that vote points at pre-training — not agents, not products.