Chai Discovery raised $400 million in Series C financing, pushing the company to a $3.8 billion valuation as pharma continues adopting AI-native chemistry platforms. The company says its models can generate de novo molecular designs for hard-to-drug targets, with its software already used by large partners including Eli Lilly and Pfizer. Chai positioned its latest release, Chai-3, as producing antibodies with improved binding affinity versus the prior platform and described progress from earlier generations such as Chai-2, including first zero-shot de novo antibody design claims tied to experimental success. The round reflects ongoing investor confidence that AI models can move from computational discovery into measurable biophysical outcomes, potentially compressing timelines in upstream drug development.