Spencer Mateega

Spencer Mateega is the 23-year-old Co-Founder and CEO of AfterQuery, a San Francisco-based applied research lab that captures expert professional knowledge and converts it into high-quality training data for AI foundation models. Founded in January 2025 and backed by Y Combinator's Winter 2025 cohort, AfterQuery raised a $30 million Series A at a $300 million valuation in April 2026, with revenues exceeding $100 million annualized. Mateega's philosophy — 'We teach machines how experts think' — drives a platform connecting roughly 100,000 domain professionals in finance, legal, and software to frontier AI labs hungry for reasoning-rich data.