Traditional exchanges match buyers directly with sellers through an order book. Decentralized exchanges (DEXs) use a different model. They rely on pools of capital deposited by users to facilitate trades. When you provide liquidity to one of these pools, you earn a share of the trading fees generated by every swap that uses your capital.

How liquidity pools work

A liquidity pool is a smart contract holding reserves of two (or more) tokens. A USDC/ETH pool, for example, holds a balance of both USDC and ETH. When a trader wants to swap USDC for ETH, they trade against the pool. The pool sends them ETH and receives their USDC. The price is determined by a mathematical formula that adjusts based on the ratio of the two tokens in the pool.

This system is called an automated market maker (AMM). The most widely used formula is the constant product formula (x * y = k), where x and y represent the quantities of each token and k is a constant. As one token's supply in the pool decreases (because traders are buying it), its price increases relative to the other token.

What you earn as a liquidity provider

Every trade that passes through the pool generates a fee, typically 0.05% to 1% of the trade value depending on the pool and platform. That fee gets distributed to liquidity providers proportional to their share of the total pool.

If you've deposited 5% of a pool's total liquidity, you earn 5% of all trading fees generated by that pool. During high-volume trading periods, these fees can accumulate quickly. During quiet periods, returns slow down accordingly.

Some pools also distribute additional incentive rewards in the platform's governance token. These incentives can significantly boost your total return but come with the caveat that the reward token's value can fluctuate.

How to provide liquidity

The process is straightforward. You deposit an equal value of both tokens into the pool. If you're adding liquidity to a USDC/ETH pool and ETH is priced at $3,000, depositing 1 ETH requires depositing $3,000 in USDC alongside it. The pool issues you LP (liquidity provider) tokens that represent your share of the total pool.

When you want to withdraw, you return your LP tokens and receive your proportional share of both tokens in the pool. The amounts you receive back may differ from what you deposited, depending on how the price ratio between the two tokens changed while your liquidity was in the pool. This difference is called impermanent loss, which is covered in detail in a later article.

Concentrated liquidity

Newer AMM designs, like Uniswap v3, let you concentrate your liquidity within a specific price range. If ETH is trading at $3,000, you might provide liquidity only in the $2,500 to $3,500 range. Your capital is more efficient within that range because it captures a higher share of trades. But if the price moves outside your range, your liquidity becomes inactive and stops earning fees.

Concentrated liquidity earns higher returns within the selected range at the cost of requiring more active management. You need to adjust your range as the market moves, which turns passive liquidity provision into a more active strategy.

Risks of providing liquidity

Impermanent loss is the primary risk. When the price ratio between the two tokens in your pool changes significantly, you end up with more of the token that dropped in value and less of the one that appreciated. The net result is that your position is worth less than if you had simply held both tokens separately. Impermanent loss is explored in depth later in this category.

Smart contract risk exists because your funds are held in a smart contract. If the contract has a vulnerability, funds can potentially be drained. Using well-audited protocols with long track records reduces this risk but doesn't eliminate it.

Low liquidity risk affects smaller or newer pools. If you're a large portion of a small pool, exiting your position can move prices significantly, reducing the value you receive on withdrawal.

When providing liquidity makes sense

Liquidity provision works best when you're already holding both tokens in a pair and expect them to trade within a relatively stable range. Stablecoin pairs (USDC/USDT) carry minimal impermanent loss risk because both tokens target the same value. Volatile pairs (like ETH/MEME) carry significant impermanent loss risk and require higher fee income to compensate.

Evaluate the total return (fees plus any incentive rewards) against the risk of impermanent loss and the opportunity cost of simply holding the tokens. If the math works in your favor and you're comfortable with the smart contract risk, liquidity provision can be a productive use of capital that would otherwise sit idle.