AfterQuery, the San Francisco-based AI training-data startup, has reportedly raised a new funding round at a $3.2 billion valuation—more than 10x its $300 million valuation from its $30 million Series A just five months earlier in April, making it the fastest startup to reach unicorn status in Y Combinator's history according to partner Gustaf Alströmer. Founded by 22- and 23-year-old founders from YC's Winter 2025 cohort, the company had reached a $100 million annualized revenue run rate as of April, with named customers including Nvidia, Legora, and Korea's Motif Technologies. The startup employs knowledge professionals—doctors, lawyers, and other specialists—to train AI models and agents on professional task completion patterns rather than just factual accuracy. The round was first reported by Forbes; specific investors and the funding amount were not disclosed.