Chai Discovery raised $400 million in Series C financing, pushing the company’s valuation to $3.8 billion and accelerating deployment of its AI platform for de novo molecular design. The San Francisco company says its software generates fully new molecular designs from scratch and is already used by pharma partners including Eli Lilly and Pfizer. Chai’s latest model release, Chai-3, is positioned as an improvement over prior versions, with the company reporting higher experimental performance on binding and target engagement. The firm describes progress particularly around difficult-to-drug and “undruggable” targets. The round underscores continued investor appetite for AI-native discovery companies that can demonstrate integration with large pharma and measurable gains in preclinical hit-finding efficiency. Chai says it has already shifted its models from “promise to deployment” in partner pipelines.