What is Compound Finance?
Compound Finance is one of the foundational money-market protocols in DeFi. Robert Leshner and Geoffrey Hayes deployed the first version on Ethereum in September 2018, and the pooled-liquidity model they introduced — where suppliers earn interest from a shared pool rather than being matched peer-to-peer — became the architecture every subsequent lending protocol copied.
COMP, the governance token, launched in June 2020 alongside the liquidity-mining program that ignited "DeFi Summer." Suppliers and borrowers received COMP proportional to interest accrued, creating the first large-scale token distribution that rewarded protocol usage. The program attracted billions in TVL in weeks and established yield farming as a standard mechanism.
Compound v3, branded Comet, launched on Ethereum mainnet in August 2022 and has since deployed on Arbitrum, Base, Optimism, and Polygon. Comet's single-collateral design — each market has one base borrowing asset — dramatically reduces the systemic risk of v2, where a bad collateral could drain multiple asset pools simultaneously.
How Compound Lending and Borrowing Works
The Comet model is deliberately straightforward. Each market has one base asset (typically USDC or ETH) that users borrow. Borrowers post collateral from an approved list of assets — currently ETH, wBTC, stETH, cbETH, and a small number of other tokens — and draw against it at a variable rate determined by utilization.
- Supply the base asset (USDC, ETH) to earn the supply APY. Interest accrues per Ethereum block.
- Or supply approved collateral assets to unlock borrowing power. Collateral earns no interest in Comet — only the base asset does.
- Borrow the base asset up to your collateral factor limit. The borrow rate rises automatically as utilization increases.
- A liquidation bot steps in when your position's health factor falls below the threshold, repaying part of the debt and claiming collateral at a discount.
- COMP governance votes control every parameter: collateral factors, liquidation penalties, interest rate curves, and new market listings.
The single-collateral design means a bad listing can only affect one Comet market, not the whole protocol. That is the core trade-off: less flexibility than Aave v3 eMode or Morpho vaults, but also less systemic contagion risk.
Security and Audit Record
Compound has operated since 2018 without a core protocol exploit — one of the longest clean records in DeFi. Audits have been conducted by OpenZeppelin, Trail of Bits, ChainSecurity, and ABDK. The Comet codebase received additional reviews before each new chain deployment.
The main historical incident was a governance bug in the reward accrual contract in September 2021, which over-distributed approximately $90 million in COMP before governance could pause it. The bug was in the rewards contract, not the lending engine itself, and no user funds were lost. The 2021 incident is informative because it shows how governance-controlled upgrades introduce their own risk vectors even in an otherwise battle-tested system.
- Oracle: Chainlink price feeds with backup staleness checks on each Comet deployment.
- Governance: 48-hour time-lock on all protocol upgrades, giving the community a window to detect and react to malicious proposals.
- Bug bounty: Active program with payouts up to $150,000 on Immunefi.
- Pausing: Guardian multisig can pause individual markets without a governance vote in emergencies.
Yields and Competitive Rates
Compound's base-asset supply rates are competitive with Aave on the same assets. USDC supply APY on the Ethereum Comet typically runs between 4% and 8% depending on utilization, with spikes during periods of high stablecoin demand. On Base and Arbitrum, rates can differ by 1-3 percentage points due to local demand conditions.
Additional COMP rewards are distributed to both suppliers and borrowers in active markets. The size of the reward boost has shrunk as the liquidity-mining program from 2020 has wound down, but the DAO continues to adjust incentives per market through governance votes.
- USDC Comet (Ethereum): base supply APY 4-8%, plus variable COMP rewards
- ETH Comet (Ethereum): base supply APY 2-5%, tracking ETH borrow demand
- Base and Arbitrum markets: often 0.5-2% higher than Ethereum mainnet due to fewer competing lenders
- Collateral assets earn 0% in Comet — only the base asset accrues interest for suppliers
Users who want to maximize yield on collateral assets typically use a separate yield layer (e.g., supply wstETH to earn staking yield, then use it as collateral in Compound) rather than expecting Compound itself to pay on collateral.
Compound vs Aave vs Morpho: Choosing the Right Protocol
The three major DeFi lending protocols serve overlapping but distinct use cases. Compound's Comet design sits between Aave v3's breadth and Morpho Blue's permissionless composability.
- Compound Comet: conservative single-collateral markets, strong institutional adoption for USDC borrowing, lower complexity and lower systemic risk than Aave v2-era designs.
- Aave v3: wider asset and chain coverage, eMode for correlated-asset efficiency, native GHO stablecoin, and higher TVL for large positions. Default choice when you need maximum liquidity or unusual assets.
- Morpho Blue: permissionless vault creation lets curators assemble custom risk parameters. Highest flexibility and often the best rates, but also more due diligence required on which vault you are depositing into.
- Maple Finance: institutional credit lines with off-chain underwriting. Not a pooled-liquidity market — more like a regulated fixed-income product sitting on a blockchain.
For a retail user who wants to borrow USDC against ETH with minimal complexity, Compound Comet on Base or Ethereum remains a solid default. For advanced DeFi users who want yield optimization, Morpho vaults built on top of Compound or Aave typically outperform the base protocols.
This review is for informational purposes only and does not constitute financial advice. DeFi lending carries smart-contract risk, liquidation risk, and market risk. Never supply more than you can afford to lose.