What Is Compound Finance and How It Works
Learn how Compound Finance works on Ethereum. Supply assets to earn interest, borrow crypto with collateral, and understand cTokens, liquidation, and COMP.
What Is Compound Finance and How It Works
Compound Finance is a decentralized lending and borrowing protocol built on the Ethereum blockchain. It lets anyone supply cryptocurrency to earn interest or borrow assets by depositing collateral. All lending and borrowing is managed by smart contracts, removing the need for banks or intermediaries.
How Compound Finance Works: Supply, Borrow, and Interest Rates
Compound Finance creates separate liquidity pools for each supported asset, such as DAI, USDC, ETH, or WBTC. Users interact directly with these pools instead of matching individual lenders and borrowers.
- Supplying: When you deposit an asset into Compound, you start earning interest immediately. The interest rate is not fixed — it changes based on the utilisation rate of the pool, which is the ratio of borrowed funds to total deposits. Higher demand to borrow drives the supply rate up; lower demand drives it down.
- Borrowing: To borrow from Compound, you first must supply a different asset as collateral. The protocol calculates how much you can borrow based on a collateral factor (a percentage of the collateral’s value). You pay interest on the borrowed amount, and that interest rate also floats with the utilisation rate.
The core mechanism is entirely algorithmic. No bank officer approves loans — the smart contract enforces the rules automatically.
The Role of cTokens in Compound Finance
When you supply an asset to Compound, you do not simply hold your original token in the pool. Instead, you receive a cToken (e.g., cDAI, cETH) that represents your deposit plus the accrued interest. These cTokens are ERC-20 tokens that you can hold, transfer, or use in other DeFi applications.
The exchange rate between the cToken and the underlying asset increases over time. For example, if you deposit 10 DAI, you receive a certain amount of cDAI. As interest accumulates, each cDAI becomes redeemable for more than one DAI. This mechanism allows interest to compound automatically without any manual action from the user.
| Token Type | Examples | Purpose |
|---|---|---|
| Underlying Asset (supplied) | DAI, ETH, USDC | The token you deposit or borrow |
| cToken (received when supplying) | cDAI, cETH, cUSDC | Represents your deposit + interest; value grows over time |
cTokens are the backbone of Compound’s accounting. They make it possible to earn interest while retaining liquidity — you can always swap cTokens back for the underlying asset on the protocol.
Risk Management in Compound Finance: Liquidation and Collateral
Borrowing in Compound requires over-collateralisation – you must deposit more value in collateral than you borrow. This protects lenders from defaults. If the value of your collateral falls too close to the value of your loan, your position becomes eligible for liquidation.
- Every asset has a liquidation threshold (expressed as a percentage of collateral value). Once your borrow amount exceeds this threshold, anyone can repay part of your loan on your behalf and seize your collateral at a discount.
- For instance, if you supply ETH worth a certain amount and borrow USDC, and the ETH price drops sharply, your collateral may no longer cover the loan. A liquidator repays a portion of your debt and receives ETH from you at a discounted price, plus a liquidation penalty.
Liquidations are automatic and happen in seconds. Beginners often misunderstand how quickly a cascade can occur during volatile markets.
⚠️ Warning: Never borrow the maximum amount allowed by the collateral factor. A small price dip can trigger liquidation, resulting in a penalty on top of losing part of your collateral. Always maintain a comfortable buffer.
Governance and the COMP Token in Compound Finance
Compound is governed by holders of its native COMP token. COMP gives its holders the right to propose and vote on changes to the protocol. Topics include adjusting collateral factors, adding new assets, or changing interest rate models.
- Proposals must collect a minimum number of votes to pass.
- Voting power is proportional to the amount of COMP a user holds (or delegates).
- The system is designed to evolve without relying on a central team, though the community often follows the lead of active contributors.
You can obtain COMP by using the protocol — a portion of newly minted COMP is distributed to suppliers and borrowers as a reward. This incentivises participation and decentralises governance further. For full details, visit the official Compound governance documentation.
💡 Pro Tip: Before supplying or borrowing, check the current parameters (collateral factors, liquidation thresholds, and reserve factors) for each asset. These values can change after a governance vote, so staying updated helps you manage risk.
Practical Example of Using Compound Finance
Imagine Alice wants to earn passive income from her ETH, while Bob needs short‑term liquidity without selling his ETH.
- Alice supplies ETH to Compound. She deposits ETH and receives cETH in return. Over the following weeks, the exchange rate of cETH to ETH increases as other users pay borrow interest. Alice can redeem her cETH for more ETH than she originally deposited.
- Bob supplies ETH as collateral and borrows USDC against that collateral. He can take up to the collateral factor (e.g., 75% of the ETH value) in borrowed USDC. He pays a variable borrow rate that changes with market demand.
- One week later, the ETH price drops. Bob’s borrowed amount now represents a much higher percentage of his collateral’s value. If it crosses the liquidation threshold, a liquidator will repay part of Bob’s debt and seize some of his ETH as a penalty.
By understanding cTokens, utilisation rates, and liquidation mechanics, both Alice and Bob can use Compound effectively — Alice to earn, and Bob to access cash without selling his crypto.
Conclusion
Compound Finance is a foundational protocol in decentralized finance that introduced automated money markets with algorithmic interest rates. Its cToken model allows interest to compound seamlessly, while COMP token governance lets the community steer the protocol’s future. Whether you want to earn yield on idle assets or borrow against your holdings, Compound offers a transparent, permissionless way to participate in crypto lending and borrowing.
