Here's something that sounds almost too good to be true: a biotech startup claiming it can collapse five-year drug discovery problems into a few weeks using AI. But OpenAI-backed Chai Discovery just raised $130 million at a $1.3 billion valuation, so investors are clearly believers.

The Funding Round

General Catalyst and Oak HC/FT led Monday's Series B round, joined by Menlo Ventures, OpenAI, Dimension, Thrive Capital, Neo, Yosemite Venture Fund, Lachy Groom, SV Angel, and newcomers Glade Brook and Emerson Collective. That brings Chai's total funding to over $225 million since its founding in 2024.

Annie Lamont from Oak HC/FT and Hemant Taneja from General Catalyst are joining the board. Menlo Ventures previously led a $70 million Series A earlier this year.

What Chai Actually Does

Think of Chai as computer-aided design software, but for molecules instead of buildings. The company's AI models, including its latest Chai 2 platform, predict how molecules will interact and design custom antibodies completely from scratch—what scientists call de novo antibody design.

CEO Josh Meier, who previously engineered at OpenAI and Facebook, put it bluntly: "We're in awe of the rate of progress on the models – what looked like five-year problems just months ago are now getting solved in weeks."

The goal is to help scientists engineer molecules with the right properties for drugs and tackle diseases that were previously considered untreatable. Chai plans to use the fresh capital to accelerate research, product development, and commercialization efforts.