Compound is an autonomous Ethereum lending market governed by COMP

Compound is an algorithmic DeFi interest rate protocol where crypto suppliers earn from borrower demand and borrowers draw a base asset against on-chain collateral. It runs through smart contracts, uses utilization-based rates, and places major parameter changes under COMP governance. The protocol is best known for Ethereum money markets, the newer Comet architecture, and transparent rules for collateral, liquidation, rewards, and reserves.

How the Comet market model works

The current design is Compound III, also called Comet, and it organizes each market around a single borrowable base asset. In the original Ethereum deployment, that base asset was USDC. A user supplies the base asset to earn interest, or supplies approved collateral assets such as WETH or WBTC to support a borrow of the base asset. This design gives every market a clear debt unit instead of letting every listed asset become a borrow asset inside the same pool.

Collateral assets support borrowing capacity, but they do not accrue interest inside a Comet market. The base asset carries the interest model. That separation matters because a wallet can hold a positive balance in the base asset, a negative balance in the base asset, and separate collateral balances at the same time. The account state is visible on-chain, so applications can read balances, health, and market parameters directly from contracts.

Base assets, collateral, and signed balances

Each market tracks base balances as signed values. A positive base balance means the account has supplied the base asset and earns the supply rate. A negative base balance means the account has borrowed the base asset and pays the borrow rate. The protocol stores principal values internally, then applies supply and borrow indices that rise over time as interest accrues.

Borrow capacity comes from governance-set collateral factors. If an asset receives an 85% borrow collateral factor, an account using that asset as collateral has borrowing capacity equal to 85% of its quoted value in the base asset. Liquidation factors are separate and higher, creating a buffer between opening a borrow and becoming liquidatable. Supply caps limit how much of a collateral asset a market accepts, which reduces concentration in assets with thinner liquidity or higher volatility.

Interest rates move with utilization

Rates come from separate supply and borrow curves selected through governance. Utilization equals total borrows divided by total supply of the base asset, and the curve includes a kink where rates rise faster after demand crosses a set point. Interest accrues every second using the block timestamp, so balances update continuously as time passes and as the market becomes more or less utilized.

This mechanism makes the price of borrowing react to liquidity. When most supplied base assets sit idle, rates remain lower. When borrowers use a larger share of the pool, the borrow rate rises and the supply rate follows. The spread between what borrowers pay and what suppliers earn contributes to protocol reserves, which sit inside the market as a buffer for the system.

COMP governance controls market parameters

COMP holders and delegates govern Compound through proposals, voting, and execution through administrative smart contract functions. Governance changes include adding collateral assets, changing supply caps, updating price feeds, setting rate curve slopes, adjusting collateral factors, configuring rewards speeds, and designating emergency pause powers. Approved proposals pass through the Timelock before execution, giving the market a visible path from vote to contract change.

In Compound III, deployments beyond Ethereum use the same Mainnet governance authority with bridge receivers and local timelocks on the destination chain. That structure keeps sanctioned markets tied to COMP governance while still allowing EVM-compatible deployments. The Governor, Timelock, Configurator, Comet factory, and proxy contracts form the administrative layer behind upgrades.

Using Compound from a wallet

A typical wallet flow starts with choosing a supported market and checking the base asset, collateral options, current rates, and account liquidity. Supplying an ERC-20 token requires an approval transaction before the market contract moves the token. Borrowing uses the withdraw function for the base asset once the account has enough collateral value.

• Connect a wallet on a supported EVM network.
• Select a market and review the listed base asset.
• Approve the token before the first supply transaction.
• Supply the base asset to earn interest or collateral to open borrow capacity.
• Borrow the base asset while keeping a healthy buffer above liquidation levels.

The Bulker contract improves common interface workflows by grouping actions into one transaction. It supports sequences such as wrapping Ether into WETH, supplying collateral, borrowing USDC, transferring collateral inside the protocol, and claiming rewards. Developers use these helper flows to make wallet interactions shorter without changing the core accounting rules.

Where the older v2 design still matters

Compound v2 introduced pooled lending markets represented by cTokens. Supplying an asset minted a corresponding cToken, and the exchange rate between the cToken and the underlying asset increased as interest accrued. Assets such as DAI, USDC, ETH, and WBTC became familiar to DeFi users through this model, and many analytics dashboards, integrations, and legacy positions still reference it.

The major distinction is architectural. v2 treats each listed asset as its own money market, while Comet narrows a market around one base asset and a defined collateral set. That change makes risk controls, liquidation behavior, and gas usage more predictable for the newer design. A user comparing old and new markets should understand which version a wallet or integration is actually using.

Rewards, reserves, and liquidations are part of the engine

Importantly, Compound III reward accounting tracks accrual for suppliers and borrowers of the base asset when a rewards program is configured. Rewards use an ERC-20 token selected for that market and are claimed through the external rewards contract. The core market records the accounting, while the rewards contract handles the claim path for account owners, managers, or another caller claiming on behalf of an account.

Liquidation uses an absorb process. When an account crosses its liquidation threshold, the protocol takes the collateral, clears the debt, and leaves the user with the remaining value in the base asset after the liquidation penalty. Reserves fund the absorption, and liquidators later buy seized collateral from the protocol at a governance-configured discount when reserves need replenishment. Liquidation risk is real when collateral prices fall or borrow rates rise.

Aave, Morpho, and MakerDAO as alternatives

Aave offers broader multi-asset borrowing across many networks, with isolation modes and efficiency modes for specific collateral sets. Morpho focuses on lending optimization and peer-to-peer matching layered around underlying markets. MakerDAO centers on minting DAI against approved collateral through vaults. Compared with those systems, Compound emphasizes autonomous rate markets, visible governance control, and Comet's single-base-asset design for clearer accounting.

What makes it useful for developers and users

Developers get public contracts, readable market state, EVM compatibility, and documented helper functions for balances, rates, collateralization, rewards, and liquidation. Users get transparent rules for supplying a base asset, borrowing against collateral, and tracking account health without relying on a private ledger. The enduring appeal of Compound is its simple money-market core: liquidity enters, utilization sets rates, collateral backs debt, and COMP governance changes the rules through on-chain votes.