Usual Zero Rate (Fira)
Usual Stability Loans (USL) & Usual Zero Rate (UZR) are a DAO-operated, fixed-rate lending facility built on Euler & Fira. It allows users to borrow USD0 against bUSD0 collateral.
Market Parameters
Collateral asset
bUSD0 (Bonded USD0)
Loan asset
USD0
Base borrowing rate
0%
Protocol fee
0.10% APR (10 bps)
LTV
88%
LLTV (Liquidation threshold)
99.99%
Oracle
Fixed-price 1:1 (bUSD0/USD0)
Maturity
June 11, 2028, 11:30 UTC
Chain
Ethereum Mainnet
Interest rate contract
Immutable — cannot be changed post-deployment
How It Works
Deposit bUSD0 as collateral into the UZR market.
Borrow up to 88% of the collateral value in USD0.
Accrue a 0.10% APR fee continuously on outstanding debt.
Repay debt at any time before maturity to recover collateral.
The borrowing cost is set at deployment and cannot change. The interest rate strategy contract is immutable once the market is created.
Oracle Design
UZR uses a fixed-price oracle that values bUSD0 at a constant 1:1 ratio with USD0 for all LTV calculations. This is a deliberate design choice:
Benefit: Consistent borrowing capacity regardless of secondary market price fluctuations. Higher effective leverage compared to mark-to-market oracles.
Assumption: If bUSD0 trades below 1 USD0 on secondary markets, the protocol still values it at 1. This trust assumption is accepted given bUSD0's redemption guarantee at maturity.
Fee Structure
The 0.10% APR fee accrues continuously on outstanding debt — not per borrow event. All fees route directly to the Usual Treasury.
Borrow rate
~1.5–2%
0% + 0.10% fee
Max leverage
~8.1x
~12.3x
Fee destination
Euler + external
Usual Treasury
Oracle
Mark-to-market
Fixed 1:1
Lending Side
The Usual DAO is the sole lender on UZR. The DAO sets lending caps and supplies USD0 directly. Individual users cannot lend on this market.
This design gives the DAO full control over exposure while routing all protocol revenue to the Usual Treasury.
Migration from Euler
Migration from USL (Euler) to UZR (Fira) is executed through a dedicated migrator contract in a single atomic transaction:
DAO enables migration capacity (makes USD0 borrowable against U0R).
bUSD0 collateral is withdrawn from Euler.
bUSD0 is posted as collateral on UZR.
USD0 is borrowed on UZR at the same effective LTV (88% ceiling).
Borrowed USD0 repays the Euler debt.
The Euler loan token is burned as the position closes.
Migration is opt-in. Euler remains available; positions are not forced to migrate. No additional protocol fees are charged beyond gas costs.
Available Features
UZR supports all Fira protocol-level features:
Borrow & Repay — Deposit bUSD0, borrow USD0, repay before maturity
Leverage Loop — Recursive borrowing to amplify exposure to the bUSD0 discount-to-par convergence (up to ~12.3x)
Multiply — One-click leverage loop via a slider interface
Technical Reference
Market ID
0xA597B5A36F6CC0EDE718BA58B2E23F5C747DA810BF8E299022D88123AB03340E
IRM contract
0xdfCF197B0B65066183b04B88d50ACDC0C4b01385
Oracle contract
0x30Da78355FcEA04D1fa34AF3c318BE203C6F2145
Lending market
0xa428723eE8ffD87088C36121d72100B43F11fb6A
USD0 (loan token)
0x73A15FeD60Bf67631dC6cd7Bc5B6e8da8190aCF5
bUSD0 (collateral)
0x35D8949372D46B7a3D5A56006AE77B215fc69bC0
Risks
Multiply amplifies both upside and downside. Higher leverage means higher exposure to the following risks:
No Liquidation Before Maturity
UZR uses a fixed 1:1 oracle (bUSD0/USD0) and sets the liquidation threshold (LLTV) at 99.99%, far above the 88% maximum borrow LTV. Since the oracle price never moves, only interest accrual (0.10% APR) changes the LTV. From 88%, reaching 99.99% would take over a century. Positions cannot be liquidated before maturity.
At maturity, the Usual DAO can trigger forced liquidation to close remaining positions and enable collateral redemption. This is an intentional design for a maturity-based system, not a penalty — borrowers should repay or close positions before the maturity date.
Slippage Risk
Each loop iteration involves a USD0 → bUSD0 swap on secondary markets. At high leverage levels, the cumulative swap volume increases. Large swaps may incur price impact, especially in low-liquidity conditions.
Interest Accumulation
The 0.10% APR fee accrues on the total debt, not just the initial borrow. A 5x leveraged position accrues fees on 5x the initial collateral value in debt. Over long durations, this compounds.
Simulator
Stress-test UZR parameters, sprice, LTV, maturity, in the live simulator: simulator.fira.money
Related
Markets Overview — How Fira markets work
Liquidations — Position health and liquidation mechanics
UIP-18: UZR Launch — Governance proposal that authorized UZR deployment
Whitepaper: UZR Bootstrapping — Formal specification (Section 6)
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