AfterQuery Emerges as Y Combinator’s Quickest Unicorn with a $3.2 Billion Valuation

AfterQuery, an AI training-data startup, has allegedly secured funding that elevates its valuation to $3.2 billion, merely five months after announcing a $30 million Series A funding round which valued the company at $300 million in April.

This represents an impressive growth of over 10 times in less than half a year and, according to Y Combinator partner Gustaf Alströmer, marks the fastest ascent to unicorn status for any startup in the accelerator’s history. The founders of AfterQuery, aged 22 and 23, participated in Y Combinator’s Winter 2025 cohort just 18 months prior.

In April, the San Francisco-based firm disclosed an annualized revenue run rate of $100 million and noted its collaborations with several prestigious laboratories. Among its clients are prominent companies like Nvidia, Legora, and Korea’s AI lab Motif Technologies.

AfterQuery is part of a fresh wave of startups, taking inspiration from Mercor and Scale, that partner with professionals, such as doctors and lawyers, for model training. Instead of just ensuring accurate answers, AfterQuery focuses on preparing models and agents to operate like seasoned professionals to accomplish tasks—what the company refers to as “encoding the patterns, decisions, and reasoning of the world’s most skilled practitioners.”

Forbes was the first to report this funding round, and AfterQuery has yet to respond to requests for immediate comment.