Circle International Bermuda Limited launched cirBTC, a Bitcoin-backed token, on Arc on September 21, 2026, five days after Arc’s mainnet launch. Each cirBTC is backed 1:1 by Bitcoin held in reserve, with operations regulated by the Bermuda Monetary Authority and reserves verified on-chain through Chainlink. Users can convert BTC, cbBTC or wBTC into cirBTC through selected fee-free flows, Arc’s portal and Circle Mint, while qualifying institutions can access Circle Mint’s new Digital Asset-Backed Borrowing option. Morpho reported more than $150 million in deposits in its USDC and EURC vaults on the first day, with cirBTC used as collateral, while Aave V4 opened cirBTC, USDC and EURC markets on Arc. Around September 19 to 20, cirBTC supply stood at roughly 949 tokens, valued at about $77 million, against reserves of approximately 951 BTC; about 379 to 397 tokens were on Arc and the remainder on Ethereum. Arc uses USDC as both its gas token and primary settlement asset. Circle said the segregated custody, Bermuda regulatory structure and Chainlink verification are designed for institutions seeking compliant, auditable Bitcoin exposure in DeFi without first converting BTC into a dollar-denominated asset.