AI agents, software that performs multi-step tasks autonomously, are emerging as a new class of crypto and payments users by purchasing data, computing power, API access and other online services. Coinbase’s x402 protocol, designed to let agents pay for services without repeated human confirmation, processed more than 160 million cumulative transactions by June 2026 and between 14 million and 17.8 million transactions in a 30-day period around August. More than 90% of cumulative activity occurred on Base, while average Base transactions were about $0.13. USDC represented more than 99.99% of x402 agentic transfer volume over the latest 90 days, underscoring its early dominance in this market. Earlier figures cited more than 165 million x402 payments this year, over $50 million in cumulative volume, more than 480,000 agents in the ecosystem as of April and an estimated 99% USDC share, indicating differences in timing or measurement. Circle has reinforced its position through the Agent Stack, including gas-free nanopayments as small as $0.000001, while reporting $14.8 trillion in USDC on-chain transaction volume for the second quarter of 2026. Stablecoins are best suited to frequent machine payments, while cards and bank accounts retain advantages for larger purchases, refunds, credit and dispute resolution. Coinbase, Circle, Cloudflare, MoonPay, Mastercard, Visa, banks and wallet providers are developing a multi-rail system with spending limits, approved sellers, scoped permissions, escrow and other safeguards, but adoption, funding and protection against mistaken or malicious agent actions remain unresolved.