Chai Discovery lands $400M Series C at $3.8B valuation

Chai Discovery, a structural biology and AI-driven drug design startup, has closed a $400 million Series C funding round at a $3.8 billion valuation. The round was led by Index Ventures, with major participation from Kleiner Perkins, Sequoia Capital, and Dimension, and brings the company’s total capital raised to more than $600 million in just over eleven months. Existing backers including OpenAI, Thrive Capital, Menlo Ventures, General Catalyst, Glade Brook Capital, Avenir, Lachy Groom, and Yosemite joined the round, alongside new investors such as Bain Capital Ventures, Battery Ventures, Baillie Gifford, BDT & MSD Partners, Sapphire Ventures, and Avra.

The fresh capital will be used to accelerate Chai Discovery’s AI-driven molecular and antibody design platform, which underpins collaborations with major pharmaceutical companies including Pfizer, Eli Lilly, and Novartis. Founded in 2024, Chai Discovery previously raised a $30 million seed round, a $70 million Series A, and a $130 million Series B at a $1.3 billion valuation in December 2025, reflecting rapid investor confidence in its approach to AI-native drug discovery. The oversubscribed Series C round further cements Chai Discovery as one of the fastest-scaling AI drug design companies, positioning its Chai models as core infrastructure for biopharma partners seeking to speed up discovery pipelines.