AfterQuery reportedly becomes Y Combinator's fastest-ever unicorn

AI training-data startup AfterQuery has reportedly raised a round that valued it at $3.2 billion, just five months after announcing its $30 million Series A at a $300 million valuation in April. That’s more than a 10x increase in less than half a year and, according to Y Combinator partner Gustaf Alströmer, the fastest any startup has gone from launch to unicorn status in the accelerator’s history. AfterQuery’s founders, now 22 and 23 years old, attended Y Combinator’s Winter 2025 cohort just 18 months ago.

In April, the San Francisco startup said it had reached an annualized revenue run rate of $100 million and that it was working with many of the biggest AI labs, naming customers including Nvidia, Legora, and the South Korean AI lab Motif Technologies.

AfterQuery is among a new crop of startups following in the footsteps of Mercor and Scale that employ knowledge professionals such as doctors, lawyers, and other specialists to do model training. Rather than ensuring models answer questions accurately, though, AfterQuery trains models and agents on how to work like professionals would to complete tasks — what the company describes as “encoding the patterns, decisions, and reasoning of the world’s best practitioners.”

Forbes first reported on the round. AfterQuery could not be immediately reached for comment.

Why it matters

A jump from a $300 million to a reported $3.2 billion valuation in five months underscores how aggressively investors are pricing AI training-data startups right now, even against a report that hasn’t been independently confirmed by the company itself.