How DeFi Lending Protocols Work: Pools, Utilization and Liquidations
DeFi lending protocols let anyone lend or borrow crypto through smart contracts. Behind the simple deposit button is a system of pools, interest rate models, price oracles and automated liquidations.
The basic model
- Lenders deposit an asset into a pool and receive a token or record representing their share.
- Borrowers lock collateral worth more than they borrow.
- Borrowers pay interest, which is shared among lenders after any protocol fee.
- If a borrower’s collateral falls too far, anyone can liquidate the position for a reward.
Utilization and interest rates
Utilization is the share of a pool that is borrowed. Most protocols raise rates gradually as utilization rises and then steeply above a target level, to attract more deposits and discourage borrowing. That is why rates can jump within hours when demand spikes.
Oracles
Protocols need prices to know when a loan is under-collateralized. They get them from oracles, which aggregate market prices. A wrong or manipulated price can cause unfair liquidations or leave the protocol with bad debt.
Pooled vs isolated markets
| Pooled | Isolated | |
|---|---|---|
| Structure | Many assets share one pool of risk | Each market has its own collateral and loan asset |
| Advantage | Deep liquidity | A problem in one market does not spread |
| Trade-off | One bad asset can affect everyone | Liquidity is spread thinner |
Governance and admin controls
Parameters such as collateral factors and rate curves are often changed by governance votes or admin keys. Check who can change them and how quickly, because those changes affect your risk.
Ready to try? Read how to lend crypto step by step, or back to the crypto lending hub.
Liquidations in practice
When a position crosses the liquidation threshold, independent liquidators repay part of the borrower’s debt and receive collateral at a discount. This keeps the pool solvent but costs the borrower the liquidation bonus. In fast crashes, liquidations can cascade as falling prices trigger more selling.
Interest-bearing tokens and positions
Many protocols give lenders a token that represents their deposit and grows in value or quantity as interest accrues. These tokens can sometimes be used elsewhere in DeFi, which adds convenience but also stacks risks from several protocols.
What to check before using a protocol
- Audits, bug bounty and incident history.
- Which assets are accepted as collateral and their parameters.
- Oracle sources for each market.
- Who controls upgrades and parameter changes.
Frequently asked questions
Mostly traders and investors borrowing against their crypto, often for leverage or liquidity.
When utilization is very high, lenders may have to wait to withdraw until loans are repaid or new deposits arrive.
Debt that is no longer covered by collateral because liquidation came too late. Lenders may share the loss.
This page is for educational purposes only and is not financial, investment or tax advice. Crypto assets are volatile; you can lose all of your money.