Circle Launches Wrapped Bitcoin (cirBTC) With Chainlink Proof of Reserve

Circle has launched Circle Wrapped Bitcoin (cirBTC), a 1:1 $BTC-backed token that brings native Bitcoin onto programmable networks with segregated custody and verifiable onchain reserve data. Announced on 4 September 2026, cirBTC is live on Ethereum today, with native support planned for Circle’s Arc layer-1 blockchain once its mainnet launches.

How cirBTC’s Backing Is Structured

Every cirBTC token is backed one-to-one by native Bitcoin and redeemable one-to-one for it, a wrapped token rather than a staked or derivative product. The underlying $BTC is held through a Circle affiliate and custodied by Circle National Trust, a federally chartered national trust bank supervised by the Office of the Comptroller of the Currency. Reserves sit in accounts segregated from Circle’s corporate assets and held for the exclusive benefit of cirBTC holders, keeping the collateral legally and operationally separate from the issuer’s balance sheet. The token is issued by Circle International Bermuda Limited, a Class F Digital Asset Business licensed by the Bermuda Monetary Authority.

Chainlink Proof of Reserve for Verifiable Backing

Circle pairs segregated custody with observable backing by connecting three data points: native $BTC held in disclosed reserve addresses, the onchain reserve value published through Chainlink Proof of Reserve, and the circulating cirBTC supply across supported chains. When cirBTC is redeemed, the corresponding tokens are removed from circulation and native $BTC is released, so tokens in circulation should not exceed the $BTC held in reserve. Circle is careful to note that proof of reserve does not replace custody, redemption, or smart-contract diligence, but it lets lending protocols, market makers, and asset managers inspect the collateral without relying solely on an issuer’s statement.