Circle Internet Group switched on the public mainnet of Arc on September 16, marking the USDC issuer’s most significant expansion beyond stablecoins as it positions the open Layer 1 blockchain as an economic operating system for payments, tokenized markets and AI agents. The launch, announced by Circle , goes live with a permissioned validator set drawn from the institutions that run global finance rather than a fully decentralized network, a design choice Circle argues gives banks and asset managers the trust they need to move treasury, trading and payments onchain.
A Validator Set From Global Finance
The network’s phased rollout is secured by 11 founding validators: BlackRock, the Depository Trust & Clearing Corporation (DTCC), Galaxy, ICE, Mastercard, MoneyGram, SBI Group, Standard Chartered, Sumitomo Corporation, Visa and Worldpay (now Global Payments). Circle said more than 100 applications and more than 100 institutional and ecosystem builders are already live on or exploring Arc. BlackRock’s global head of digital assets, Robbie Mitchnick, said purpose-built blockchains can help accelerate adoption of digital asset use cases, with Arc well positioned to serve stablecoin and payment use cases at scale.
USDC-Native Finance and the Agent Economy
Arc integrates natively with Circle’s platform, anchored by USDC, which has more than $74 billion in circulation. Circle’s StableFX service enables 24/7 programmable foreign-exchange trading with near-instant settlement, while day-one trading infrastructure includes Uniswap, Aero and fomo, with tokenized assets such as Circle’s USYC money market fund, BlackRock’s BUIDL and wrapped bitcoin (cirBTC) available to trade and post as collateral. Circle also positioned Arc as the first blockchain designed from genesis for AI agents , noting USDC accounts for 98.8% of agent-driven transaction volume.
From Testnet to Mainnet
Arc’s public testnet , which Circle first unveiled in October 2025, processed more than 700 million transactions in under a year, with a community of more than 75,000 Arc House members and 1,200-plus projects built for the network. The chain is fully EVM-compatible, so existing Solidity contracts and developer tools work from day one. Chief executive Jeremy Allaire called the launch the single most significant launch in Circle’s history since USDC itself, with mainnet the start of a roadmap centered on proof of stake, privacy and scalability.