Lending

Fira's lending infrastructure includes separate markets for fixed-rate (BT-denominated) and variable-rate (USDC-denominated) lending.

Overview

Fira uses two lending market deployments:

FiraLendingMarket (Fixed-Rate)

• Loan token: BT (Bond Token)

• Collateral: Pendle PT tokens (PT-USDe, PT-sUSDe, PT-USDG)

• Interest rate model: None (IRM = address(0)) — the rate is implicit in the BT discount

• Supply: Whitelist-gated to the LiquidityInjector only

• Oracle: FiraSolvencyOracle (3-layer oracle pipeline)

VariableLendingMarket (Variable-Rate)

• Loan token: USDC

• Collateral: wstETH, cbBTC

• Interest rate model: AdaptiveCurveIrm (adjusts based on utilization)

• Supply: Permissionless via SisuVault (ERC-4626)

• Oracle: Morpho wstETH/USDC, ChainlinkOracleV2 for cbBTC/USDC

SisuVault

The SisuVault is an ERC-4626 vault that aggregates USDC deposits and supplies them to variable-rate lending markets. It is managed by a curator and allocator (Markov Labs) who control market allocation.

Vault shares (mkUSDC) represent proportional claims on the underlying USDC plus accrued interest.

Key functions

Function	Description
supplyCollateral(params, amount, user, data)	Deposit collateral
borrow(params, assets, shares, user, receiver)	Borrow loan token
repay(params, assets, shares, onBehalf, data)	Repay debt
withdrawCollateral(params, amount, user, receiver)	Withdraw collateral
liquidate(params, borrower, seizedAssets)	Liquidate undercollateralized position
getUserPosition(params, user)	View full position details
accrueInterest(params)	Update interest state

Related pages

• Fixed-Rate Lending (Feature)

• Variable-Rate Lending (Feature)

• Contract Deployments