AI training data startup AfterQuery has achieved a valuation of $3.2 billion, or approximately 21.5 billion yuan, in just five months after its April Series A round at $300 million post-money, making it the fastest company in Y Combinator history to reach unicorn status. Founded in February 2025 by college students Spencer Mateega and Carlos Georgescu, the pair originally tried to develop AI agents for financial workflows but pivoted after observing that frontier models failed on complex professional tasks due to missing expert reasoning data. AfterQuery now supplies judgment processes, step-by-step solutions, and reinforcement learning environments generated by verified professionals in finance, law, medicine, and engineering. The platform has engaged nearly 100,000 experts, and its data has been incorporated into Nvidia's Nemotron 3 Ultra model, where it raised GDPval scores from 35.3 to 46.7 in ablation tests. The company is already profitable and has secured a lead investor for a new funding round. Annual recurring revenue has grown to several times the $100 million run rate reported in April.