Circle has launched Circle Wrapped Bitcoin (cirBTC), a token backed one-to-one by native Bitcoin and now live on Ethereum following a September 4, 2026, announcement. The reserves are held through a Circle affiliate in segregated accounts at Circle National Trust, a federally chartered national trust bank supervised by the Office of the Comptroller of the Currency, for the exclusive benefit of cirBTC holders. Circle International Bermuda Limited issues the token under a Class F Digital Asset Business license from the Bermuda Monetary Authority. Chainlink Proof of Reserve publishes data from Circle's disclosed Bitcoin addresses so users and smart contracts can compare reserves with circulating supply. Circle's September 5 dashboard showed 40.03 cirBTC in circulation against 42.51 BTC in reserves, implying a calculated surplus of 2.49 BTC and coverage of about 106.21%. The figures are not described as a permanent buffer and can change as tokens are minted, redeemed or as Bitcoin moves between disclosed addresses. Proof of Reserve provides reserve visibility but is not a financial audit and does not itself guarantee custody, redemption, liquidity or smart-contract performance. Qualified businesses can mint and redeem cirBTC through Circle Mint, while other users must rely on exchanges, decentralized liquidity pools or eligible intermediaries. Circle has not said the token contract automatically blocks minting if reserve coverage falls below a threshold. Native cirBTC support is planned for Circle's Arc layer-1 blockchain when its mainnet launches, subject to regulatory approval, with additional integrations expected over time.