Stablecoins are the money layer of agentic commerce — the digital currencies that AI agents actually transact in. USDC by Circle is the primary stablecoin for x402 payments, with Circle building dedicated micropayment infrastructure (transfers as small as $0.

000001 with zero gas fees). USDT by Tether is positioning for massive scale, with CEO predictions of 1 trillion AI agents using USDT. CASH by Phantom, launched through Stripe's Open Issuance platform, represents a new breed of application-specific stablecoins designed for seamless cross-rail commerce.

Stablecoins solve the fundamental problem of AI agent payments: they provide price stability (unlike volatile crypto), programmability (unlike fiat), and instant settlement (unlike bank transfers).