Fees

Borrow APY

Solend charges an interest rate for borrowing assets. The borrow APY is set algorithmically, a function of utilization of the pool.
The following piecewise function is used:
Which then produces the following graph:

Protocol Fees

Interest Rate Spread

Interest rate spread is a percentage of the borrow interest rate that Solend receives as protocol revenue. The fee percentage varies depending on the asset.
Pool
Asset
Spread
Main
SLND
20%
Main
SOL
10%
Main
USDT
10%
Main
USDC
10%
Main
BTC
10%
Main
ETH
10%
Main
mSOL
10%
Main
stSOL
10%
Main
ORCA
20%
Main
FTT
15%
Main
RAY
15%
Main
SRM
15%
Main
soETH
20%
TURBO SOL
SOL
10%
TURBO SOL
USDC
10%
STEPN
GMT
20%
STEPN
GST
20%
STEPN
USDC
20%
Basis
rBASIS
20%
Basis
BASIS
20%

Origination Fee

Origination fee is a fee charged upon creation of a loan.
Solend's origination fees are broken down into a program fee and host fee. The program fee contributes to Solend's insurance fund. The host fee can be collected by any interface that refers loans to the protocol.
The fees for most vaults are set to 10 bips (0.1%). There's an 80/20 split between protocol and host fee. Check in app or on the Main Pool page for specific asset rates.

Liquidation Insurance Fee

Liquidation insurance fee is a percentage of the liquidation penalty that Solend receives. These funds go to the DAO treasury. The liquidation insurance fee is currently 30% of the liquidation penalty.
Liquidation bonuses exist in order to incentivize liquidators to help keep Solend solvent, providing a buffer to absorb loss from slippage. Liquidators have been well-compensated for this service, racking up an estimated $3M in profit in the first year of Solend being live on mainnet. Solend takes on the risk that liquidations are unprofitable, creating bad debt. In the event of bad debt, Solend's insurance fund is tapped to make users whole. Close to $1M has been paid out from Solend's insurance fund for such issues in the past. Taking a fee allows Solend to build up its treasury so it can continue providing users with insurance.

Solana Network Fees

There are two types of fees you pay on the Solana blockchain when transacting: transaction fees and rent fees.

Transaction fees

These fees compensate the validator network for the CPU/GPU and network resources necessary to process the state transaction. Transaction fees are extremely cheap (currently 0.000005 SOL).

Rent fees

These fees compensate the validator network for the memory resources that are required to store state in an account. Accounts which maintain a minimum balance equivalent to 2 years of rent payments are exempt from paying rent. When solend.fi is used, accounts are allocated on behalf of the user and funded with enough SOL to be rent-exempt. This amount can be recuperated later when the account is closed (though this isn't yet implemented on solend.fi). Rent fees can be expensive compared to transaction fees (~0.01 SOL), but are only paid the first time a user is interacting with Solend.