Circle Launches Bitcoin (BTC)-Backed USDC Borrowing With 1:1 cirBTC Collateral

Circle Opens BTC-Backed USDC Borrowing

Circle switched on a new borrowing rail for institutional Bitcoin holders on September 21, 2026, rolling out a service called Digital Asset-Backed Borrowing (DABB) that lets eligible Circle Mint customers borrow USDC against their BTC without selling a single coin. The mechanics, as laid out in Circle's official announcement, follow a wrap-first design: a client deposits Bitcoin (BTC) with Circle, receives Circle Wrapped Bitcoin (cirBTC) minted 1:1 against the deposited coins, and then supplies that cirBTC as collateral — from a wallet the client controls — to supported third-party lending markets on Arc or the Ethereum network. The borrowed USDC lands directly in the customer's Circle Mint balance, and once the loan is repaid the collateralized cirBTC is released back. cirBTC, the token at the center of the flow, is a wrapped Bitcoin asset fully backed 1:1 by real BTC, with reserves that Circle says can be independently verified on-chain. The rollout initially supports Morpho, the lending protocol supplying the credit markets, and Circle has signaled that Aave and other protocols will be added over time. Importantly, DABB is not a fixed-rate loan product: interest rates, collateral requirements and liquidation thresholds are set by whichever third-party lending market the client uses, and those parameters move with market conditions — meaning a drop in collateral value can trigger liquidation even though the underlying BTC was never sold. Positions are overcollateralized, and collateral flows through a customer-controlled wallet into third-party DeFi protocols rather than being lent directly by Circle itself. The service targets institutions that meet Circle Mint eligibility requirements rather than retail traders, and clients based in New York are excluded from the rollout. For treasury desks, the pitch is straightforward: dollar liquidity without parting with the coins, effectively turning idle balance-sheet BTC into working collateral inside established custody arrangements.

Institutional Lending Race Broadens

The launch lands days after Circle activated the Arc mainnet, its layer-1 blockchain built for stablecoin payments and financial markets. Arc uses USDC as its native gas token and already supports tokenized assets including BlackRock's BUIDL and Circle's own USYC, and cirBTC went live on the network on Monday, the same day the borrowing service opened. The wrapped token itself is not new: Circle first issued cirBTC on Ethereum in June 2026, where it is backed 1:1 by Bitcoin held in custody at Circle National Trust. The move also drops Circle into an increasingly crowded arena for institutional crypto-backed lending within the broader Bitcoin ecosystem. In February, Anchorage Digital partnered with Kamino to let institutions borrow against staked Solana held at Anchorage Digital Bank, giving borrowers onchain liquidity without moving collateral out of qualified custody. Bitcoin-backed models followed in March, when Lombard teamed up with Bitwise to develop a system for borrowing against BTC held in custody, with Morpho supplying the lending infrastructure — and unlike Circle's wrap-first approach, Lombard's design keeps the underlying Bitcoin in custody without wrapping or bridging it. BitGo expanded its institutional lending offering the same month, launching a financing platform for borrowing and lending against liquid, staked and locked crypto assets held in custody, with a portfolio-based model that lets multiple assets serve as collateral rather than requiring collateral to be posted for individual loans. The pattern across all three rivals is consistent: keep institutional collateral inside regulated custody while opening a path to onchain credit. Demand on the accumulation side has kept pace, with treasury buyers like Strategy's recent 950 BTC purchase after a two-week pause and Strive's $107.7M Bitcoin addition lifting corporate holdings, and lending rails give those same balance sheets a way to extract liquidity from positions they intend to keep. Readers tracking the market in real time can follow live spot and futures prices on Binance.

From Reserve to Productive Collateral

Read together, the two threads describe one arc: Bitcoin is being repositioned from a dormant reserve asset into productive collateral inside institutional Bitcoin DeFi. Circle's own announcement — the primary document behind this launch — states that cirBTC reserves are independently verifiable on-chain and that all lending parameters are set by third-party markets, not by Circle, a division of labor institutional risk desks will scrutinize closely. For corporates that built strategic Bitcoin reserve positions, DABB offers dollar liquidity without abandoning the HODL discipline; the counter-current is visible in the ECB's Pontes settlement platform, which backs euro central-bank money over public chains. Our read: wrap-first and custody-first designs will compete on who controls liquidation risk, and Circle's market-set parameters push that risk squarely to the borrower.