AfterQuery Hits $3.2B Valuation in New Series B
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AfterQuery has reportedly raised a Series B at a $3.2 billion valuation, which Y Combinator partner Gustaf Alstromer described as the fastest run from launch to unicorn status in the accelerator’s history. The news was reported on September 1, 2026.
The company works out of San Francisco, and it supplies training data to frontier AI labs.
More precisely, AfterQuery delivers datasets and reinforcement learning environments that carry specialised sector expertise. Those are the inputs labs need to push models toward professional-grade capability in specific fields, and they are hard to produce at scale because they require actual practitioners.
The jump in valuation is the striking part. In April 2026 the company announced a $30 million Series A at a $300 million valuation, led by Altos Ventures with The Raine Group participating alongside existing investors Y Combinator and BoxGroup. Five months later the number is more than ten times that.
Revenue has moved too. AfterQuery has passed $100 million in annual revenue run rate.
Demand for expert AI training data has become one of the tighter bottlenecks in model development, which is what a valuation like this is really pricing.
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