Chai Discovery has raised USD 70 million in Series A financing to accelerate its use of generative artificial intelligence for drug discovery. The round was led by Menlo Ventures through its Anthology Fund, a joint vehicle with Anthropic, and values the San Francisco-based start-up at roughly USD 550 million, according to people familiar with the terms. New investors Yosemite, DST Global Partners, SV Angel, Avenir and DCVC joined the raise alongside existing backers OpenAI, Thrive Capital and Dimension. The capital will be used to scale the company’s Chai-2 platform, which designs antibodies de novo with a hit rate approaching 20 percent—about 100 times higher than earlier computational methods that typically succeed 0.1 percent of the time. Menlo partner Greg Yap and Mikael Dolsten, former chief scientific officer at Pfizer, will take seats on Chai’s board. Management said the additional expertise and funds will allow Chai to pursue traditionally “undruggable” targets and move its first internally developed antibodies toward pre-clinical studies. The financing underscores surging venture appetite for AI-enabled drug discovery, coming the same day Hong Kong-listed XtalPi announced a potential USD 6 billion collaboration with DoveTree. Investors say recent performance gains from models such as Chai-2 are shortening development timelines and could reshape how biologic therapeutics are invented.