USDC Powers 99.3% Of X402 AI Agent Payments

Circle CEO Jeremy Allaire identified payments between artificial intelligence agents as a major emerging opportunity for USDC during an Aug. 19 earnings webcast.

Allaire said software agents need a reliable unit of account that supports fast, inexpensive and predictable settlement. Circle’s second-quarter figures showed that 99.3% of payment volume using the x402 agent-payment protocol settled in USDC.

USDC dominates x402 rather than every AI payment protocol

The 99.3% figure applies specifically to x402 activity measured by Circle. It should not be interpreted as USDC processing 99.3% of every payment made by AI agents across all networks and protocols.

“Over 99%” refers to x402 agent-payment volume settling in USDC, according to Circle’s published results. The company has not provided comparable data covering the entire AI-payment market.

The x402 protocol uses the internet’s HTTP 402 “Payment Required” status code. It allows an autonomous agent to receive a price, authorize a payment and access a digital service without opening a traditional account or waiting for a human to approve each transaction.

Possible applications include payments for data, computing resources, application programming interfaces and digital content. USDC gives agents a dollar-denominated settlement asset whose value is designed to remain stable.

Circle sees USDC connecting agents with paid services

Circle launched Agent Stack in May 2026. The platform supported more than 900 paid services by the end of the second quarter, according to the company’s results.

The company plans to expand its agent products during the second half of 2026. Circle said the roadmap would move beyond enabling agents to make payments by introducing tools that let them earn income.

Blockchain adoption for autonomous payments is developing across several networks. In related coverage, AI agents completed more than 1.4 million XRP Ledger transactions, while Base and Solana recorded larger volumes associated with x402 services. USDC was the main settlement asset across much of that activity.

These transaction counts demonstrate technical usage, but they do not establish the size or profitability of the broader agent economy. Many machine payments remain small, reflecting early-stage testing and low-value service purchases.

Cross-border settlement remains a larger established market

Allaire also identified cross-border transfers, capital markets and retail commerce as major USDC growth areas. Unlike autonomous-agent payments, these uses already operate within large existing markets dominated by banks, card networks and money-transfer companies.

Circle Payments Network connects regulated financial institutions using USDC for international settlement. Its partnership with Nium gives participating institutions access to local-currency payouts across more than 190 countries and 100 currencies.

Circle is also testing retail and corporate payments with established financial companies. JCB and Circle recently began testing USDC for treasury transfers and merchant payments in Japan. The proposed retail phase would examine payments at physical stores, including transactions involving international visitors.

Allaire said offline commerce is moving toward instant digital methods such as QR-code payments. However, availability will depend on merchant integration, local rules and consumer access to compliant wallets.

Circle’s September launch will test its payment strategy

Circle ended the second quarter with $73.3 billion of USDC in circulation, up 19% year over year. Quarterly onchain transaction volume rose 151% to $14.8 trillion.

Those figures include trading, transfers and other blockchain transactions rather than payments alone. Circle reported seven million meaningful wallets, defined as wallets holding more than $10 in USDC.

The next infrastructure milestone is Arc’s public mainnet launch on Sept. 16. Circle said the network will include privacy capabilities, tokenized-asset support and tools for programmable agent finance.

Arc’s launch could provide Circle with more control over the infrastructure supporting USDC payments. Adoption will depend on whether developers, financial institutions and merchants deploy live services rather than limited pilots.