Chai Discovery Announces $400M Series C to Advance AI-Driven Molecular Design

Chai Discovery, the company engineering AI models to discover new molecules led by Joshua Meier and Matthew McPartlon, has announced a $400M Series C fundraise to further accelerate progress. The round, which values the company at $3.8B, was led by Index Ventures alongside Kleiner Perkins, Sequoia Capital, and Dimension. These firms were joined by new investors Bain Capital Ventures, Battery Ventures, Baillie Gifford, BDT & MSD, Sapphire Ventures, Avra Capital, and other notable investors. Existing investors Thrive Capital, OpenAI, Oak HC/FT, Menlo Ventures, General Catalyst, Glade Brook, Avenir, Lachy Groom, and Yosemite also joined the round.

Chai Discovery develops AI models that accelerate pre-clinical drug discovery by predicting and reprogramming molecular interactions. Its platform enables pharmaceutical and life sciences companies, including Eli Lilly and Pfizer, to design better therapeutics faster, bringing greater precision and predictability to drug development, particularly for hard-to-drug and previously undruggable targets.

“AI drug discovery has moved from promise to deployment,” said Joshua Meier, Co-founder and CEO of Chai Discovery. “Chai’s models are already helping partners design better molecules, accelerate work on difficult targets, and tackle challenges that have long limited traditional drug discovery.”

Chai Discovery's latest model, Chai-3, improves target success rates and binding affinity, producing antibodies that bind more effectively to intended targets. It builds on Chai-2, introduced in 2025 as the first zero-shot generative platform for fully de novo antibody design to achieve double-digit experimental success rates, marking a significant advance over previous computational approaches.

“Chai Discovery has combined cutting-edge AI research with strong commercial execution,” said Nina Achadjian, Partner at Index Ventures. “The team is already working with some of the world's largest pharmaceutical companies, demonstrating the real-world impact of its technology. The company is well positioned to help define the next generation of AI-driven drug discovery.”

“Chai Discovery is advancing AI-driven drug discovery with both technical innovation and commercial momentum,” said Ilya Fushman, Partner at Kleiner Perkins. “With leading pharmaceutical companies already using its models, the team is well positioned to help shape the future of AI-powered therapeutics.”

“Chai Discovery is translating advances in AI into real-world drug discovery,” said Pat Grady, Partner at Sequoia Capital. “With leading pharmaceutical companies already using its platform, the team is demonstrating how AI can accelerate the development of new therapeutics and tackle some of medicine’s most complex challenges.”

“Chai Discovery represents one of the most compelling opportunities at the intersection of AI, science, and computing,” said Zavain Dar, Founder at Dimension. “The team’s rapid pace of innovation and ability to translate advanced research into real-world impact have strengthened our conviction since our initial investment. We are excited to support Chai as it enters its next phase of growth.”