AfterQuery reportedly becomes Y Combinator’s fastest-ever unicorn, now valued at $3.2B

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AI training-data startup AfterQuery has reportedly raised a round that valued it at $3.2 billion. This 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 that any startup has gone from launch to unicorn status in the accelerator’s history. AfterQuery’s founders, today 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 labs. It has named companies including Nvidia, Legora and the Korean AI lab Motif Technologies, as customers.

AfterQuery is among the new crop of startups following in the footsteps of Mercor and Scale that employ knowledge professionals like doctors, lawyers, and other specialists, to do model training. However, rather than ensuring that models answer questions accurately, 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.