A joint report by Keyrock, Coinbase, and Tempo reveals that AI agent payments have evolved from a concept to a mature ecosystem over the past 12 months. From May 2025 to April 2026, settlement amounts reached $73 million across 176 million transactions, with an average transaction size of $0.31. Over 104,000 AI agents are now registered across more than 15 directories and registries. The report highlights that traditional payment networks struggle with fixed fees for microtransactions under $1, making stablecoins the default settlement layer for machine commerce. Notably, over 98% of AI agent settlements utilize Circle's USDC. However, this reliance poses risks related to reserve management, regulatory status, and technical infrastructure.