AfterQuery becomes Y Combinator’s fastest-ever unicorn at $3.2B valuation

AfterQuery, an AI data company that barely existed 20 months ago, just hit a $3.2 billion valuation. That makes it the fastest company in Y Combinator’s nearly two-decade history to reach unicorn status, a milestone that typically takes startups years to achieve, not months. The company closed a $30 million Series A in April 2026 at a $300 million valuation. By September 2026, it had multiplied that figure by more than ten. What AfterQuery actually does The company’s core business is deceptively simple: it provides human-curated training datasets and reinforcement learning environments to AI labs. Large language models are only as good as the data they learn from, and most of the internet’s publicly available text has already been scraped dry. AfterQuery’s edge is its network of roughly 100,000 verified professionals across finance, medicine, law, and software engineering. These aren’t random crowdsourced workers labeling images. They’re domain experts generating the kind of nuanced, high-quality data that separates a mediocre AI model from one that can actually reason about complex problems. The client list reads like a who’s who of frontier AI development. OpenAI, Google DeepMind...