Liquidity Pools — How AMMs Work, How You Earn, and What Impermanent Loss Really Means

The Problem Liquidity Pools Solve

Traditional exchanges use order books — buyers and sellers post bids and asks, and trades execute when prices match. This requires active market makers constantly quoting prices on both sides of the book. In early DeFi, liquidity was too thin and on-chain transaction costs too high for order books to function reliably. Every price update would require a transaction. Every market maker cancellation would cost gas. The model simply did not work.

Automated Market Makers (AMMs) solved this by replacing order books with algorithmic pricing curves and pooled liquidity. Instead of matching a buyer with a seller, AMMs let traders swap against a shared pool of tokens held in a smart contract. Price discovery is handled by a mathematical formula, not by individual market participants. The result: any token pair with sufficient liquidity can be traded on-chain, 24/7, without a counterparty ever needing to be present.

How AMMs and Constant Product Pools Work

The most common AMM mechanism — and the one that established the standard — is Uniswap's constant product formula. It is elegant in its simplicity:

When a trader buys token Y with token X, they add X to the pool and remove Y from it. Because k must remain constant, reducing Y forces X to increase proportionally — which means the price of Y (in terms of X) rises. The formula, not a market maker, sets the new price. This is why large trades in small pools cause significant "price impact" — you are moving along the curve.

A concrete example: a USDC/ETH pool holds 1,000,000 USDC and 500 ETH. k = 500,000,000. A trader buys 1 ETH. They send USDC in and receive ETH out. After the swap, there is slightly less ETH in the pool, so the ratio has shifted — ETH is now priced slightly higher in USDC terms than before the trade. Arbitrageurs watch this pool against other markets and keep the price aligned with external exchanges, which is the mechanism that drives impermanent loss (more on that below).

LP Tokens — What They Are and What They Represent

When you deposit tokens into a liquidity pool, the protocol mints LP (Liquidity Provider) tokens and sends them to your wallet. These tokens are a claim on your proportional share of the pool. If the pool holds $1,000,000 in total assets and you deposit $10,000, you receive tokens representing 1% of the pool.

LP tokens are not static receipts — they accrue value over time as trading fees accumulate. Every time a trader executes a swap, a fee (typically 0.3% on Uniswap v2, ranging from 0.05% to 1% on v3) is added to the pool's reserves. This increases the value of every LP token proportionally. When you burn your LP tokens to withdraw, you receive your share of the total pool — original principal, plus accumulated fees, minus any impermanent loss.

LP tokens are also composable. Many DeFi protocols accept LP tokens as collateral, or allow you to stake them to earn additional token emissions. This stacking of yield is the basis of yield farming — taking your LP tokens and depositing them into a second protocol on top of the base fee income.

Impermanent Loss — The Mechanism Explained

Impermanent loss (IL) is the most important concept for any LP to internalize before committing capital. It is also one of the most misunderstood. IL does not mean you lose money in absolute terms — it means you would have had more money if you had simply held the tokens instead of providing liquidity.

Here is the mechanism: AMMs automatically rebalance the token ratio in the pool as prices move. When ETH's price rises relative to USDC, arbitrageurs buy ETH out of the pool at the lower on-chain price until the pool price matches external markets. After this, your position holds less ETH (the appreciating token) and more USDC (the stable token). You participated in the upside only partially — compared to just holding ETH outright.

The approximate impermanent loss by price change ratio for a standard 50/50 pool:

The loss is called "impermanent" because if the price ratio returns to exactly where it was when you deposited, the divergence loss disappears entirely. It only crystallizes into a real loss when you withdraw at a different price ratio than you entered. This is why the key question every LP must answer before entering is: will the trading fees I earn exceed the impermanent loss I incur over my intended holding period? For stable pairs (USDC/USDT), IL is near zero because prices rarely diverge. For volatile pairs (ETH/SHIB), IL can easily exceed fee income during a strong trend.

Concentrated Liquidity — Uniswap v3

Uniswap v2 spreads your liquidity across the entire price range from zero to infinity. This means that at any given moment, the vast majority of your capital is sitting idle at price levels where no trading is happening. Capital efficiency is poor.

Uniswap v3 introduced concentrated liquidity — LPs specify a price range within which their capital is active. If you provide liquidity to ETH/USDC between $2,500 and $3,500, all of your capital is deployed only when ETH trades in that range. When the price is within range, you earn fees at a dramatically higher rate on your deployed capital compared to v2. When the price moves outside your range, you stop earning entirely and your position converts to 100% of one token.

Concentrated liquidity is a double-edged mechanism. Narrow ranges can generate 10–50× more fee income per dollar than v2 — but require active management. When prices trend strongly, positions go out of range and need to be repositioned. Wide ranges behave more like v2 with moderate capital efficiency gains. Very tight ranges around the current price earn the most fees but carry the highest out-of-range risk and amplified impermanent loss. For passive LPs, wide ranges or v2-style pools are generally more appropriate than very tight concentrations.

What Makes a Good Liquidity Pool to Enter

Before depositing capital into any liquidity pool, evaluate these factors carefully:

• Volume / TVL Ratio

  The higher this ratio, the more fees the pool generates per dollar of liquidity locked. A pool with $1M TVL and $500K daily volume (0.5×) will typically generate far better returns than a $10M pool doing the same $500K volume (0.05×). Sort pools by this metric before entering.
• Fee Tier

  Uniswap v3 offers 0.01%, 0.05%, 0.3%, and 1% tiers. Stablecoin pairs (USDC/USDT) concentrate in the 0.01–0.05% tier. Blue-chip pairs (ETH/USDC) use 0.05–0.3%. Exotic or volatile pairs use 0.3–1%. Higher fees mean more income per trade — but if the fee is too high, volume moves to a cheaper pool.
• Token Volatility and Correlation

  Higher volatility and lower correlation between the two tokens means higher impermanent loss risk. Stablecoin pairs have near-zero IL. ETH/BTC has moderate IL because both assets trend together. ETH paired with a low-cap altcoin can have devastating IL if the altcoin trends strongly in either direction relative to ETH.
• Protocol Age and Audit Status

  Never provide liquidity on unaudited protocols or pools that launched within the last few weeks. Smart contract risk is existential — a single exploit can drain every LP position. Uniswap, Aerodrome, Velodrome, and Raydium have extensive audit histories and proven track records. Newer forks or anonymous teams require extreme caution.
• Incentive Emissions

  Many pools supplement trading fee income with additional token emissions (liquidity mining rewards). This can significantly boost effective APR — but recognize that emission rewards are denominated in the protocol's governance token, which may depreciate over time. Model the fee income alone as the baseline, and treat emissions as a bonus.