What Is Compound Finance? Algorithmic Money Markets Explained

Compound Finance is a decentralized lending protocol that lets users supply crypto assets into shared liquidity pools to earn interest and borrow against collateral, using an algorithmic interest rate model that adjusts automatically based on each pool's utilization — the ratio of borrowed funds to total supplied liquidity — rather than rates set by any centralized party.

Compound was one of the earliest protocols to popularize this pooled, algorithmic lending model, and its core design has directly influenced most of the lending protocols that followed, including Aave — see our DeFi lending explainer for the general mechanics this piece builds on.

How supplying assets works: cTokens

When a user deposits an asset into Compound, they receive a corresponding cToken (for example, cUSDC for supplied USDC) representing their claim on the pool. Unlike a token whose balance grows over time, a cToken's quantity stays fixed relative to what you deposited, but its exchange rate relative to the underlying asset increases steadily as interest accrues — meaning the same number of cTokens becomes redeemable for a growing amount of the underlying asset over time. This is a different accounting approach than Aave's aTokens (which grow in balance directly), but the practical effect — your deposit earning interest automatically — is conceptually similar.

How the interest rate model works

Compound's interest rates for both suppliers and borrowers are set by a formula tied to a pool's utilization rate. As more of a pool's supplied liquidity gets borrowed, utilization rises, and the model responds by raising the borrow rate — this discourages further borrowing (since it's getting more expensive) and, because supplier interest is generally derived from a share of what borrowers pay, also raises the rate suppliers earn, encouraging more supply to meet the demand. As utilization falls, both rates ease back down.

Many of Compound's markets use a "kinked" rate curve — a model where rates rise gradually up to a target utilization point, then rise much more steeply beyond it, creating a strong incentive to keep utilization from climbing too close to 100% (which would otherwise risk leaving some suppliers unable to withdraw their funds on demand, since only unborrowed liquidity in the pool is immediately available for withdrawal).

Feature	Description
Deposit receipt	cToken — fixed quantity, growing exchange rate
Rate driver	Pool utilization (typically a "kinked" curve)
Borrower cost	Rises as utilization approaches target/maximum
Supplier yield	Derived from a share of borrower interest payments

Collateral and liquidation

To borrow on Compound, a user supplies collateral and can borrow up to a percentage of its value, set per asset based on that asset's liquidity and volatility (similar in spirit to Aave's LTV system). If the value of posted collateral falls enough relative to a user's borrowed amount, the position becomes eligible for liquidation, where a third party can repay part of the outstanding debt in exchange for a discounted portion of the collateral — protecting the protocol's overall solvency. See the liquidation glossary entry for how this general mechanism works across lending protocols.

Governance: COMP and the "liquidity mining" legacy

Compound is also historically significant for popularizing "liquidity mining" — distributing its governance token, COMP, to users who supply or borrow on the protocol, as an incentive to bootstrap usage. This 2020 event is widely credited with kicking off the broader "DeFi Summer" period, as other protocols adopted similar token-incentive models to attract liquidity. COMP token holders today vote on protocol parameters, new asset listings, and upgrades through an on-chain governance process.

Risks to understand

The risk categories are similar to any pooled lending protocol: smart contract risk (mitigated by audits and Compound's long operating history, but never eliminated), oracle risk (incorrect or manipulated price feeds can trigger unwarranted liquidations — see our DeFi oracles explainer), and liquidity risk (in periods of very high utilization, suppliers may temporarily be unable to withdraw immediately, since only unborrowed funds are available on demand). Borrowers should also be aware that rate models can shift meaningfully during periods of high demand, changing the cost of an existing variable-rate loan without warning.

How Compound compares to Aave

Both protocols solve a similar problem with broadly similar mechanics, but differ in specific details — interest rate curve shapes, supported assets, risk parameters, and additional features like Aave's isolation mode or safety module. See our direct Aave vs. Compound comparison for a fuller side-by-side breakdown.

Bottom line

Compound pioneered the algorithmic, utilization-driven interest rate model that much of DeFi lending is now built around, letting rates adjust automatically to supply and demand without a centralized rate-setter. As with any lending protocol, your real risk is a function of how close to the maximum borrowable amount you choose to operate — check current yield rates and a specific asset's collateral parameters directly before opening a leveraged position.