Chai Discovery has raised $400M in a Series C round that values the AI biotech startup at $3.8B, tripling its valuation from seven months ago. The round was led by Index Ventures, Kleiner Perkins, Sequoia Capital and Dimension, bringing Chai’s total funding to over $600M.
From seed to $600M in two years
Founded in 2024, Chai develops AI models that predict and reprogram molecular interactions for drug discovery. The company launched its first model, Chai-1, within its first year, followed by a $30M seed round, later raising $70M (Series A), $130M (Series B), and now $400M (Series C) in rapid succession. Its latest model, Chai-3, powers deals with Eli Lilly, Pfizer and Novartis.
Real antibodies from pure AI design
In preprint studies, Chai-2 achieved a 16% hit rate in fully de novo antibody design — roughly 100-fold better than earlier computational methods. The company argues this is high enough to skip traditional high-throughput screening entirely. A subsequent preprint showed the antibodies carry drug-like properties and can hit historically difficult targets.
AI drug discovery enters deployment phase
CEO Joshua Meier said the industry has moved from promise to deployment, with partners using Chai’s models to design better molecules against difficult targets. The raise signals growing conviction among top-tier VCs and pharma that AI-native drug design is graduating from experimental to operational.
