AfterQuery, an AI training-data startup, has reportedly closed a new funding round that values the company at EUR 3 billion. The milestone arrives just five months after the San Francisco company announced its EUR 26 million Series A at a EUR 259 million valuation in April.
That marks more than a 10x jump in less than half a year. According to Y Combinator partner Gustaf Alströmer, it represents the fastest any startup has moved from launch to unicorn status in the accelerator’s history.
From Y Combinator to unicorn in record time
AfterQuery’s founders, currently 22 and 23 years old, took part in Y Combinator’s Winter 2025 cohort roughly 18 months ago. The rapid ascent underscores how quickly AI infrastructure companies are attracting capital in the current market.
Back in April, the startup reported an annualized revenue run rate of EUR 86 million and said it was working with many of the largest AI labs. Named customers include Nvidia, Legora, and the Korean AI lab Motif Technologies.
How AfterQuery trains AI models
AfterQuery belongs to a new wave of startups following the path set by Mercor and Scale. These companies employ knowledge professionals such as doctors, lawyers, and other specialists to handle model training work.
The difference lies in the approach. Rather than focusing on whether models answer questions accurately, AfterQuery trains models and agents to work the way professionals would when completing real tasks. The company describes this as “encoding the patterns, decisions, and reasoning of the world’s best practitioners.”
This method aims to teach AI systems the actual workflows and decision-making processes used by experts, rather than simply optimizing for correct responses. As enterprises seek AI agents capable of executing complex professional tasks, demand for this kind of specialized training data has grown sharply.
A fast-moving AI funding landscape
The new valuation places AfterQuery among the most rapidly scaling AI startups of 2026. The company’s climb from a EUR 259 million valuation to EUR 3 billion in five months reflects the intense investor appetite for firms building the data pipelines behind advanced AI models and agents.
Forbes first reported details of the round. AfterQuery could not be immediately reached for comment.
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