- Circle’s Agent Stack lets AI agents hold USDC, follow spending rules, discover services and make autonomous payments without manual approval.
- USDC settles about 99% of x402 transaction volume, giving Circle a strong position as AI agents increasingly use programmable payment systems.
- Circle faces competition from Coinbase, Stripe and Tether as autonomous payment networks expand across stablecoins and other digital assets.
Circle is expanding USDC as AI agents begin initiating transactions, according to Shoal Research. The report examines Circle’s Agent Stack, including wallets, Nanopayments, service discovery, and developer tools. It details how agents can hold funds, follow spending rules, find services, and pay programmatically.
USDC Gains Ground In Agent Payment Activity
It says software can trigger many agent payments without manual approval. Consequently, transaction count and payment volume may better reflect agent activity.
USDT has about $185 billion in circulation, compared with $73 billion for USDC. However, USDC has taken most combined USDC and USDT transfer volume. Its monthly transaction count has increased roughly fivefold in two years.
It cites x402, which lets agents pay for web resources through HTTP requests. USDC was its initial payment rail and still settles 99% of x402 transaction volume. Artemis data cited by Shoal Research supports the figure.
Circle Adds Tools For Autonomous Payments
In May 2026, Circle launched the Circle Agent Stack with five components. They include Nanopayments, Agent Wallets, the Circle CLI, Agent Marketplace, and Circle Skills.
Nanopayments support transfers as small as $0.000001. They use Circle Gateway to batch authorizations and reduce settlement costs. Agent Wallets let agents manage funds under preset spending policies.
Operators can set spending limits, allowlists, blocklists, and permitted transaction types. The Circle CLI gives developers an interface for wallets, CCTP, Gateway, and policy management. Agent Marketplace helps agents discover x402-compatible services, while Circle Skills provides information for AI coding tools.
Circle Faces Competition Across Payment Rails
Circle’s Agent Stack builds on USDC, while other companies are developing competing payment systems. Coinbase created x402 and operates its default facilitator. It also offers AgentKit, CDP wallets, and Base.
Stripe has developed Tempo and the Machine Payments Protocol, which supports stablecoins, cards, and Bitcoin. Meanwhile, Tether has pursued AI payments through its QVAC SDK and Wallet Development Kit.
It notes an issue for Circle’s business model. Agents may increase transaction activity while using funded wallets more frequently, increasing velocity without matching growth in stablecoin balances. Circle scheduled Arc’s mainnet launch for September 2026, using USDC as its native gas token.
