Chai Discovery raises $400M Series C for AI molecule models used by Lilly, Novartis and Pfizer

Chai Discovery, a San Francisco-based AI drug discovery company, has raised a $400 million Series C round led by Index Ventures, alongside Kleiner Perkins, Sequoia Capital, and Dimension, valuing the startup at approximately $3.8 billion.

Chai’s AI models are designed to generate new molecular designs from scratch and help pharmaceutical partners like Eli Lilly, Pfizer, and Novartis pursue previously “undruggable” or hard-to-target disease pathways.

The company operates as a software and R&D partner for pharma, providing its AI platform to accelerate preclinical drug discovery without developing its own medicines.

Chai has signed multiple partnerships, including a collaboration with Novartis for AI-driven antibody discovery, a license agreement with Pfizer to speed up drug discovery, and a collaboration with Lilly’s TuneLab platform to offer its AI models to select biotechs.

Founded in 2024 by Joshua Meier, Jack Dent, Matthew McPartlon, and Jacques Boitreaud, Chai has now raised over $600 million in total funding and is positioned as one of the leading AI-driven molecular design platforms in biopharma.