Chai Discovery raises $400M Series C
AI drug-design startup Chai Discovery raised $400M led by Index Ventures at a $3.8B valuation. Chai-3 is already used by Lilly, Novartis, and Pfizer.
Chai Discovery, the AI drug-design startup, raised a $400 million Series C on July 13 at a $3.8 billion valuation, nearly tripling the $1.3 billion mark it set seven months earlier in a December round. Index Ventures led the round, joined by Kleiner Perkins, Sequoia Capital, and Dimension, with returning backers Thrive Capital and OpenAI. The raise brings the two-year-old company’s total funding to roughly $630 million.
Chai Discovery builds generative AI models for molecular design, aimed at engineering antibodies and other “hard to drug” targets rather than screening for them by trial and error. Its latest model, Chai-3, is already in commercial use: Eli Lilly, Novartis, and Pfizer each have agreements to run parts of their drug-discovery work through it, according to the company.
Tomorrow’s medicines should be designed with the precision, speed and scale of modern engineering, and this support helps us move faster towards that future.
That’s co-founder and CEO Joshua Meier, in the funding announcement.
What it means for you
The valuation jump is less interesting than what is behind it. Eli Lilly, Novartis, and Pfizer are large, risk-averse companies, and their willingness to route real drug programs through Chai-3 is a stronger signal than the funding round itself. The number to watch is not the next valuation mark but whether any of these collaborations produces a named clinical candidate, the point where “AI-designed” stops being a pitch line and starts being a track record.
It also sharpens the choice pharma companies and AI labs are each making: license a model like Chai-3, or build the capability in-house the way Anthropic did with its own drug discovery program. Both bets assume AI-assisted molecular design works at scale, which is still being proven one clinical candidate at a time.