Circle Launches Arc Mainnet With Over 100 Day-One Builders

Circle Internet (CRCL ) Group announced the public mainnet launch of Arc on September 16, 2026. Arc is an open Layer 1 blockchain the company describes as purpose-built for financial markets, real-time money movement, and agentic economic activity, and it debuts with native integration into Circle’s full-stack platform, including USDC, which Circle states has more than $74 billion in circulation, plus more than 100 applications and more than 100 institutional and ecosystem builders spanning global banks, asset managers, payment networks, exchanges, custodians, DeFi protocols, wallets, and AI platforms live on day one.

Jeremy Allaire, Circle’s co-founder, chairman, and chief executive officer, called Arc “the single most significant launch in Circle’s history since USDC itself” and said the network is built for a world where both people and machines transact. Robbie Mitchnick, global head of digital assets at BlackRock (BLK ), said in the same announcement that purpose-built blockchains can help accelerate adoption of digital asset use cases and that Arc appears well positioned to serve stablecoin and payment use cases at scale.

Circle lists six design choices behind the network: transaction fees paid in USDC with no volatile native token required; sub-second deterministic finality; opt-in privacy for confidential transactions and balances with view keys, currently in development for network-wide release; a native home for USDC, EURC, and tokenized real-world assets with Circle StableFX providing 24/7 cross-currency settlement; an architecture designed from genesis for AI agents as economic actors; and post-quantum signatures supported from launch alongside deterministic consensus.

Circle Payments Network is integrated natively into Arc, moving money across borders for a fraction of a cent and settling in near real time, according to the company. Circle StableFX is live on Arc at launch, offering 24/7 programmable foreign exchange across more than 20 fully reserved stablecoins, with local currency stablecoins active or onboarding including AUDD, BRLA, JPYC, MXNB, TRYB, and ZARU among a wider listed set.

Aero, fomo, and Uniswap (UNI ) anchor the network’s day-one trading infrastructure, while Circle’s USYC tokenized money market fund, the Securitize-tokenized BUIDL treasury fund, private credit funds, and cirBTC, Circle’s institutional-grade programmable bitcoin, supply assets to trade, lend, and post as collateral. Arc’s blog states cirBTC is convertible one-to-one from BTC, cbBTC, or wBTC with no fees, with reserves independently verifiable onchain in real time. Aave and Morpho anchor Arc’s onchain credit markets at launch, with Bitwise, Cumberland, Dialectic, Galaxy, Gauntlet, Keyrock, and Steakhouse Financial supporting through curated vault strategies, risk oversight, and the supply of USDC and EURC for borrowing and lending. Aave Labs founder and chief executive Stani Kulechov said Aave is doubling down on the Circle ecosystem with a new Aave V4 market on Arc.

Founding Validators and the Day-One Ecosystem

Arc is operated by a permissioned validator set, and Circle said the network will see a phased rollout from a founding validator cohort that, alongside Circle, includes BlackRock, The Depository Trust & Clearing Corporation, Galaxy, ICE, Mastercard, MoneyGram, SBI Group, Standard Chartered (STD.DE ), Sumitomo Corporation, Visa, and Worldpay, now Global Payments (GPN ). “Arc’s native capabilities, including predictable fees and instant finality, address real friction points these customers raised,” said Michael Blaugrund, vice president of strategic initiatives at ICE, adding that ICE is applying its experience securing critical market infrastructure in support of the network. SBI Holdings chairman and chief executive Yoshitaka Kitao said the group will contribute to Arc’s operation and governance as a founding validator, and noted that SBI VC Trade became the first and only company in Japan to distribute USDC in March 2025.

Around the validator core, Circle said more than 100 institutional and ecosystem builders were already live on or exploring Arc’s private mainnet ahead of the public launch. Global banks listed include BNY, BTG Pactual, HSBC, Lead Bank, Societe Generale, Standard Chartered, and State Street (STT ). Asset managers and real-world asset issuers include Bitwise, BlackRock, Dinari, Janus Henderson, New York Life Investment Management in partnership with Centrifuge, Maple, Matrixdock, ProShares, and xStocks by Payward. Digital asset exchanges named include Binance, Bitso, Bitvavo, Bybit, Gate, Kraken, KuCoin, MEXC, OKX, OSL, Upbit, and Wenia; Arc’s blog states Coinbase will be live on the network soon. Custody providers include Anchorage, BitGo, Ceffu, Copper, Fireblocks, and Zodia Custody, and digital wallets include Ledger, MetaMask, Phantom, Rainbow, and Trust Wallet.

Circle released two builder tools alongside mainnet, detailed in Arc’s launch-day blog post. Arc Studio is an onchain coding agent that generates applications complete with smart contracts, application logic, and deployment-ready code, while Arc App Kits is a unified software development kit for core onchain fund flows such as payments, swaps, onramps, and yield. The first kits are Onramp Kit, which embeds fiat-to-USDC funding flows with Apple Pay and debit cards with built-in identity verification, and Earn Kit, which offers in-app earn opportunities through lending protocols such as Morpho. Arc Portal gives users a single entry point to fund agent wallets, set spend limits, and delegate onchain tasks, and Circle Agent Stack provides policy-controlled agent wallets, nanopayments powered by Circle Gateway, and an emerging agent marketplace. Circle states USDC accounts for 98.8% of agent-driven transaction volume, citing a Dune query, and that the overwhelming majority of agent-to-agent payments settling over the x402 standard have settled in USDC since Circle Agent Stack launched in May 2026. Circle CCTP and Circle Gateway extend Arc’s reach across more than 20 supported blockchains.

ARC Token Genesis Mint and the Road Ahead

Circle completed the genesis mint of the ARC token in the United States during launch week, creating the full initial supply of 10 billion tokens, a step the company says makes it the first publicly traded company to mint a network token for a new layer-one blockchain. ARC is designed to serve as a digital commodity intended to act as the native coordination mechanism for security, utility, and governance on Arc, with network fees remaining payable in USDC. Circle said the initial mint is not a commitment to publicly launch ARC, describing it instead as a technical milestone as the network explores a transition from proof of authority toward proof of stake in 2027.

The roadmap also sets out Network Sectors, purpose-built environments for different classes of financial activity: a Privacy Sector for opt-in confidential transactions, a Payment Sector targeting low-cost payments at more than 100,000 transactions per second, and an Agent Sector for verifiable agent identity and auditable records. Arc supports post-quantum signatures today, with broader post-quantum protections in development.

Circle said Arc’s testnet processed more than 700 million transactions in under a year, and that its developer community includes more than 75,000 active Arc House members and 10,000 Architect ambassadors who have built more than 1,200 projects. Arc is fully compatible with the Ethereum (ETH ) Virtual Machine, so existing Solidity contracts and developer tools work on day one.

Circle first announced the founding validator cohort on August 5, 2026, when Arc was in private mainnet and targeting the September 16 public launch. That announcement said BlackRock was expected to deploy its BUIDL tokenized fund on Arc and detailed a Circle collaboration with DTCC to enable tokenization of Depository Trust Company-custodied assets on Arc beginning in the second half of 2027, with DTC-tokenized assets intended to carry the same protections, rights, and safeguards investors receive with traditionally held assets.

Arc is launched by Arc Network Services LLC and operated by a permissioned validator set, according to the announcement, which notes the entity provides software services only and that Arc has not been reviewed or approved by the New York State Department of Financial Services or any other regulatory authority.

Circle scheduled an Arc mainnet launch event to stream live at 2 p.m. ET on September 16, 2026.