Chai Discovery

Chai Discovery is an AI structural-biology company building foundation models for molecular design. It positions itself as infrastructure for antibody and protein discovery rather than as a drug developer with its own pipeline: its product is the models, which drugmakers license and build on. It launched publicly in September 2024 with backing from OpenAI and Thrive Capital, and raised a 400 million dollar Series C in July 2026.

Its models have moved quickly. Chai-1, released in September 2024, predicts the three-dimensional structures of biomolecules, in the lineage of AlphaFold. Chai-2, in June 2025, took on fully de-novo antibody design, generating new antibodies against a target from scratch, and Chai describes it as the first zero-shot antibody design platform to reach double-digit experimental hit rates. Chai-3, disclosed in June 2026 as part of a Pfizer license, is its most advanced model; Chai says it doubles Chai-2's success rate and produces antibodies that meet required therapeutic standards, including multi-specific antibodies and molecules against hard-to-drug targets.

In 2026 its customer list filled with large drugmakers. Eli Lilly signed a biologics discovery collaboration in January and expanded it in June to run through Lilly's TuneLab platform. Pfizer licensed the platform in June, gaining early access to Chai-3 and a custom model trained on Pfizer's own data. Novartis and argenx followed in July, and Bristol Myers Squibb began an antibody discovery collaboration in August. Financial terms were not disclosed for the Pfizer or Bristol Myers Squibb deals.

As with all generative design in biology, a designed antibody is a starting point that still has to be made, tested and carried through trials. The hit rates are Chai's own measurements on targets it chose, so the real test is whether its partners take Chai-designed molecules into the clinic.