AMM (Automated Market Maker) is the core engine of decentralized exchanges (DEXs). It replaces traditional order books and market makers by using mathematical formulas and liquidity pools to automatically match trades. Well-known DEXs like Uniswap, PancakeSwap, and Curve are all built on AMM mechanisms. If you want to try DEX trading, you'll first need cryptocurrency, which you can buy on the Binance official website.
Why Do We Need AMMs?
In traditional finance and centralized exchanges, trades are executed through an order book: buyers place buy orders, sellers place sell orders, and the exchange matches them. This approach requires sufficient participants on both sides to ensure liquidity.
On blockchains, slow transaction speeds and high gas fees make the traditional order book model inefficient. AMMs solve this problem through smart contracts and liquidity pools — users trade against the pool rather than directly with other traders.
How Does an AMM Work?
The core of an AMM is a mathematical formula. The most classic one is the constant product formula used by Uniswap V2:
x × y = k
Where:
- x = the quantity of Token A in the pool
- y = the quantity of Token B in the pool
- k = a constant (unchanged when no liquidity is added or removed)
When a user swaps Token A for Token B, the amount of Token A in the pool increases while Token B decreases, but their product remains constant. The ratio of change determines the trade price.
Example: Suppose a pool holds 100 ETH and 300,000 USDT, so k = 30,000,000.
A user wants to buy ETH with 3,000 USDT:
- New USDT amount = 303,000
- New ETH amount = 30,000,000 / 303,000 ≈ 99.01
- The user receives approximately 0.99 ETH
The effective price is about 3,030 USDT/ETH, slightly higher than the pool's initial price of 3,000 USDT/ETH. This difference is the "Price Impact" caused by the trade.
Major AMM Models
Constant Product Market Maker (CPMM)
The Uniswap V2 model, using x × y = k. Suitable for general trading pairs but produces high slippage on large trades.
Constant Sum Market Maker (CSMM)
Uses x + y = k. Theoretically zero slippage, but impractical because one token could be completely drained.
Hybrid Market Maker
Curve's StableSwap model combines the constant product and constant sum formulas. It behaves like a constant sum (low slippage) when prices are near 1:1 and like a constant product when prices diverge. It is especially well-suited for stablecoin swaps.
Concentrated Liquidity
An innovation introduced by Uniswap V3, allowing liquidity providers to supply liquidity within specific price ranges. Capital efficiency can increase by hundreds of times within the active price range.
Weighted Pools
Balancer's model supports multi-token pools with unequal weights, where the weighted product of all token quantities equals a constant.
Advantages of AMMs
- Permissionless Trading: Any token can create a liquidity pool without listing approval
- Always Available: Operates 24/7 with no trading-hour restrictions
- Decentralized: No intermediaries, reducing counterparty risk
- Anyone Can Be a Market Maker: Ordinary users can become liquidity providers and earn trading fees
Disadvantages of AMMs
- Slippage: Large trades cause significant slippage, especially in low-liquidity pools
- Impermanent Loss: Liquidity providers face impermanent loss risk
- MEV Attacks: Trades may be front-run by miners or bots
- Limited Capital Efficiency: Most liquidity in traditional AMMs sits idle
- No Limit Orders: Traditional AMMs only support market swaps
Security Tips
When trading on AMM-based DEXs, keep these safety measures in mind:
- Set Slippage Carefully: Set a reasonable slippage tolerance based on the token's liquidity to avoid sandwich attacks
- Check Price Impact: If the Price Impact exceeds 5%, it means liquidity is insufficient or the trade size is too large — consider splitting into smaller trades
- Verify Pool Authenticity: Confirm that the token contract address is correct; scam tokens may create fake pools with the same name
- Beware of Low-Liquidity Pools: Newly created pools with low liquidity are extremely risky and may be scams
- Use MEV Protection: Enable Uniswap's MEV protection or use tools like Flashbots to prevent front-running
- Test with Small Amounts: Use a small amount for your first trade with a new token. You can download the official Binance app (iPhone users, see the iOS installation guide) to check whether the token is also listed on a centralized exchange
What Is the Difference Between AMMs and Order Books?
AMMs price assets automatically using mathematical formulas without requiring direct buyer-seller matching, while order books need both sides to place orders matched by an engine. AMMs are more suited for on-chain trading; order books are better for high-frequency trading and precise pricing.
Why Do AMMs Have Slippage?
Because AMMs dynamically price assets based on supply and demand. The more of a token you buy, the fewer remain in the pool, and the higher the price goes. This price change is slippage. The larger the pool, the smaller the slippage for the same trade size.
What Is a Sandwich Attack?
A sandwich attack occurs when an MEV bot inserts a transaction before and after yours: it buys first to push the price up, waits for you to buy at the higher price, then sells for a profit. Setting reasonable slippage and using MEV protection can help prevent this.
What Are LP Tokens in an AMM?
LP tokens (Liquidity Provider Tokens) are receipts you receive after depositing assets into a liquidity pool, representing your share of the pool. When you redeem them, you exchange your LP tokens for your assets plus any accumulated fees.
What Is the Difference Between Uniswap V3 and V2 AMMs?
V2 uses full-range liquidity, distributing funds across the entire price range from 0 to infinity. V3 introduces concentrated liquidity, allowing LPs to provide liquidity within specific price ranges, dramatically improving capital efficiency but adding management complexity.