Chai Discovery raised $400 million in Series C financing, pushing the AI drug-discovery firm’s valuation to $3.8 billion and signaling continued investor confidence in end-to-end model-driven molecule design. The company’s software generates de novo molecular designs and is already used by large pharma partners including Eli Lilly and Pfizer. Chai said its latest model, Chai-3, delivers improvements in target success rates and binding affinity, including tighter antibody binding relative to earlier systems. The funding arrives as biopharma leans into AI to compress early discovery timelines while managing the persistent risk that candidates fail in later clinical stages.