Chai Discovery raises $400 million, valued at $3.8 billion

Chai Discovery's new $400 million financing lifts the San Francisco biotech AI startup to a $3.8 billion valuation, a sharp jump from the $1.3 billion mark set in its $130 million Series B in December 2025. The company had already raised nearly $230 million before this latest round, after a roughly $30 million seed in 2024 and a $70 million Series A in August 2025. In June, the company was already in talks for a $400 million round at a $3.4 billion valuation, showing how fast investor expectations moved before the latest price was set.

Founded in 2024 by Joshua Meier, Jack Dent, Matthew McPartlon and Jacques Boitreaud, Chai has built its case around Chai-2, a zero-shot antibody design platform. The company says Chai-2 has produced double-digit experimental hit rates, with near-20% hit rates cited in company materials, while earlier computational methods were around 0.1%. Meier previously worked at OpenAI, a background that has helped make Chai one of the more closely watched names in the AI-drug-discovery market.

The company has also turned those technical claims into pharmaceutical relationships. On Jan. 9, 2026, Chai announced a collaboration with Eli Lilly and Company under which Lilly would deploy Chai's frontier AI platform to design novel biologic therapeutics for multiple targets and receive a purpose-built model trained on Lilly data. On July 13, 2026, Chai said Novartis would gain access to its AI design models, including Chai-3, for therapeutic antibody discovery across multiple targets, in an agreement that Chai said built on more than a year of technical engagement.

Chai's backers and supporters listed in company materials include OpenAI, Thrive Capital, Menlo Ventures and Dimension, while Oak HC/FT and General Catalyst have been among the investors drawing attention to the company as it has moved from seed stage to multibillion-dollar pricing in less than three years. The FDA says AI use is increasing across the drug product life cycle, including nonclinical, clinical, postmarketing and manufacturing phases, but the harder question for Chai and its peers is whether faster molecular design can keep translating into approved medicines, not just bigger venture rounds.