AI data and expert network company Mercor has closed a $750 million Series D funding round, reaching a valuation of $20 billion. This marks a doubling of its valuation from $10 billion in October 2025. The round attracted major investors including Benchmark, Felicis, Fundomo, Apollo, G Squared, General Catalyst, GladeBrook Capital, Nvidia, Salesforce, Sapphire Ventures, StepStone VC, XTX Ventures, and Zoom. Founded in San Francisco in 2023, Mercor initially operated as an AI recruitment platform before pivoting to supply high-quality human experts for frontier AI labs such as OpenAI. These professionals—including doctors, lawyers, and engineers—are engaged on an hourly basis to support model post-training, evaluation, and reinforcement learning from human feedback (RLHF).