AI training-data startup AfterQuery has reportedly closed a new financing round valuing the company at $3.2 billion, making it Y Combinator's fastest-ever launch-to-unicorn, according to YC partner Gustaf Alstromer. The mark-up comes just five months after AfterQuery announced a $30 million Series A at a $300 million valuation in April, and only 18 months after its 22- and 23-year-old founders graduated from YC's Winter 2025 batch.
10x in five months
The new round, first reported by Forbes on September 1, 2026, represents more than a 10x valuation lift in under half a year — and it lands as AfterQuery says it has crossed a $100 million annualised revenue run rate. Named customers include NVIDIA, legal-AI startup Legora and Korean AI lab Motif Technologies, alongside "many of the biggest labs."
Not just answers, but how experts work
AfterQuery sits in the same category as Mercor and Scale AI, employing doctors, lawyers, engineers and other knowledge professionals to produce training data for frontier models. Its differentiation is teaching models and agents how to complete tasks the way experts do — what the company calls "encoding the patterns, decisions and reasoning of the world's best practitioners" — rather than just ensuring the model returns a correct answer.
YC's fastest ever
Alstromer's "fastest-ever unicorn" claim sets a new bar for a batch of AI-native startups from YC's recent cohorts that are racing to $1B and beyond in months rather than years. The trajectory tracks other 2026 rounds like this week's YC-backed European deals and Conveo's $50M Series A, and mirrors the broader boom in expert-labelled training data as frontier labs push into agentic, task-completing systems.
What AfterQuery has not said
The startup declined immediate comment and the exact size of the new round and its lead investor have not been publicly disclosed. Even so, the reported terms slot AfterQuery into a small club of AI companies that have doubled or tripled their valuations in the second half of 2026, alongside Wonderful's $5B round.
Reporting based on coverage from Forbes, TechCrunch, Decrypt and Dealroom.