How Token Swaps Work: AMMs, Liquidity Pools & Slippage

How Token Swaps Work: AMMs, Liquidity Pools, and Slippage Explained

Decentralized Finance (DeFi) has transformed how digital assets are traded globally. On traditional centralized exchanges, buying or selling crypto relies on order books matching buyers and sellers. However, on decentralized exchanges (DEXs), trading happens entirely on-chain without an intermediary, order book, or centralized custodian.

When you execute an instant trade inside a self-custody wallet like Axxion Wallet, you interact with smart contracts that automate pricing and trade settlement instantly. Understanding what happens under the hood—from Automated Market Makers (AMMs) to price slippage—helps you trade smarter, lower your costs, and protect your assets in DeFi.

To better understand the broader security advantages of non-custodial trading, read our guide on what a self-custody crypto wallet is and why it matters.

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The Evolution from Order Books to Automated Market Makers

Centralized crypto exchanges use an order book model. Buyers submit bid prices, sellers submit ask prices, and a matching engine fills orders when buy and sell prices align. While efficient for high-frequency trading, order books are difficult to maintain on public blockchains due to network latency and high gas costs for every order placement, cancellation, or modification.

Decentralized exchanges solved this bottleneck by introducing the Automated Market Maker (AMM) model. Instead of trading against another human trader, you trade against a smart contract loaded with reserves of two or more tokens.

The Constant Product Formula

Most classic AMM protocol algorithms (such as Uniswap v2 or SushiSwap) use a mathematical model called the Constant Product Market Maker formula:

$$x \times y = k$$

Where:

• x represents the quantity of Token A in the pool.
• y represents the quantity of Token B in the pool.
• k is a fixed constant that must remain unchanged during a swap (excluding pool trading fees).

When you deposit Token A into the liquidity pool to receive Token B, the supply of Token A ($x$) increases, while the supply of Token B ($y$) decreases. To keep the product $k$ constant, the price of Token B relative to Token A increases dynamically based on the ratio of remaining tokens.

Key Takeaway: AMMs do not rely on external price feeds or order books. Instead, asset prices on a DEX are calculated algorithmically based on the proportional balance of tokens remaining inside the liquidity pool.

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Deep Dive into Liquidity Pools and Liquidity Providers

Without liquidity, an AMM cannot function. A liquidity pool is a smart contract containing locked crypto tokens provided by users known as Liquidity Providers (LPs).

When LPs fund a liquidity pool, they deposit equal monetary values of two paired tokens (for example, $1,000 worth of ETH and $1,000 worth of USDC). In exchange, they receive LP tokens, which represent their proportional share of the liquidity pool's reserves.

```

+-------------------------------------------------------------+

| LIQUIDITY POOL |

| |

| Token A (e.g., 100 ETH) x Token B (e.g., 300,000 USDC) |

| = k |

+-------------------------------------------------------------+

^ |

User Swaps ETH | | User Receives USDC

| v

+----------------+

| TRADER |

+----------------+

```

How Liquidity Providers Earn Fees

Every time a trader executes a swap through a pool, a small protocol swap fee (typically 0.05% to 0.30%) is charged. This fee is automatically distributed to all LP token holders proportional to their share of the pool.

When LPs decide to withdraw their funds, they burn their LP tokens to reclaim their original underlying tokens plus their accumulated portion of swap fees.

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Understanding Price Impact vs. Slippage Tolerance

Two critical factors dictate the final amount of tokens you receive during a swap: Price Impact and Slippage Tolerance.

1. Price Impact

Price impact is the direct price movement caused by your own trade relative to the size of the liquidity pool.

If a pool holds 10 ETH and 30,000 USDC, purchasing 5 ETH removes half the pool's ETH reserves. To satisfy $x \times y = k$, the required USDC price per ETH spikes drastically. Large orders relative to pool size suffer severe negative price impact.

2. Slippage Tolerance

Slippage represents the difference between the expected price when you submit a trade transaction and the actual executed price when the transaction is confirmed on-chain.

Because blockchain networks require time to process and validate transactions, market volatility or competing transactions can alter pool reserves while your trade is pending in the mempool.

• Low Slippage Tolerance (e.g., 0.1% - 0.5%): Protects you from unexpected price shifts, but risks transaction failure if network volatility causes prices to move beyond your limit.
• High Slippage Tolerance (e.g., 2.0% - 5.0%): Ensures trade completion during extreme volatility, but leaves you vulnerable to worse execution prices or front-running attacks.

To prevent transaction failures caused by inadequate gas settings during volatile market swaps, read our breakdown on understanding gas fees on Ethereum, BNB Chain, and Solana.

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MEV, Front-Running, and Sandwich Attacks

Because public blockchain transactions enter an open staging area called the mempool before confirmation, opportunistic actors known as Maximal Extractable Value (MEV) bots continuously scan for pending swap transactions.

If you set your slippage tolerance too high on a large swap, an MEV bot can execute a sandwich attack:

1. Front-Run: The bot submits a swap transaction ahead of yours with a higher gas fee, driving up the token price.
2. Victim Trade: Your transaction executes at the top edge of your allowed high-slippage limit.
3. Back-Run: The bot immediately sells its tokens at the newly inflated price, capturing a risk-free profit at your expense.

To guard against malicious dApps or suspicious contract approvals that target active DeFi traders, review our guide on how to spot and avoid crypto wallet drainer scams.

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Impermanent Loss: The Primary Risk for Liquidity Providers

While liquidity providers earn active swap fees, they face a specific structural risk known as Impermanent Loss (IL).

Impermanent loss occurs when the market price of the deposited assets diverges in either direction compared to when they were deposited into the pool. Because the AMM rebalances token ratios automatically as traders arbitrage the pool against global spot prices, LPs effectively hold more of the depreciating asset and less of the appreciating asset.

If the LP withdraws their funds while asset prices are diverged, that "impermanent" loss becomes permanent. LPs must evaluate whether generated swap fees exceed potential impermanent loss over time.

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How Smart DEX Aggregators Optimize Token Swaps

Trading directly against a single liquidity pool is not always capital efficient. Modern self-custody wallets utilize DEX aggregators to optimize trade execution.

Instead of routing a $50,000 swap through a single liquidity pool with high price impact, a DEX aggregator splits the transaction across multiple DEX protocols (such as Uniswap, Curve, and Balancer) and multi-hop paths (e.g., Token A → USDC → Token B).

```

/---> Pool 1 (30% Route) ---

/ \

[ Trader ] ---> Aggregator ----> Pool 2 (50% Route) ----> [ Received Tokens ]

\ /

\---> Pool 3 (20% Route) ---/

```

This intelligent routing minimizes overall price impact, reduces slippage, and guarantees the best final rate for the user.

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How to Execute Safe and Efficient Swaps in Axxion Wallet

Axxion Wallet brings intuitive, multi-chain token swaps directly into your hands without sacrificing privacy or custody control.

Because Axxion Wallet is strictly self-custodial, your recovery phrase and private keys never leave your personal device. Read more on how local keys are protected in our article on biometrics, device passcodes, and local wallet encryption.

Best Practices for Swapping Tokens inside Axxion Wallet:

• Check Token Liquidity: Avoid swapping high volumes into newly created or low-liquidity pools.
• Customize Slippage Wisely: Use auto-slippage settings or set manual boundaries (0.5% - 1.0%) for major pairs like ETH/USDT.
• Verify Gas Limits: Ensure you hold enough native network gas tokens (such as ETH, BNB, or SOL) to complete pool interactions.
• Review Smart Contract Approvals: Revoke outdated token spend allowances periodically to maintain strict wallet hygiene.

For more technical walkthroughs and troubleshooting guides, explore the official Axxion Wallet Help Centre or browse our latest tutorials on the Axxion Crypto Blog.

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Risk Disclaimer

Cryptocurrency trading, token swaps, and interacting with decentralized finance (DeFi) liquidity pools carry inherent risks, including smart contract vulnerability, high price volatility, impermanent loss, and execution slippage. This article is provided strictly for educational and informational purposes and does not constitute financial, investment, or legal advice. Always conduct independent research before interacting with DeFi protocols.

Review our complete terms of service and usage conditions at the Axxion Terms and Privacy Policy pages.

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Frequently asked questions

Why did my token swap fail while still charging a gas fee?

When a DEX token swap fails due to slippage exceeding your tolerance or insufficient liquidity, the blockchain transaction reverts to protect your funds. However, validators or miners still performed computational work to process the transaction up to the failure point, which requires network gas fees.

What is the recommended slippage tolerance setting for standard token swaps?

For high-liquidity token pairs (such as ETH/USDC or WBTC/USDT), a slippage tolerance between 0.1% and 0.5% is generally recommended. For volatile or low-liquidity tokens, higher slippage (1.0% to 3.0%) may be required, but beware of MEV sandwich attacks.

Does Axxion Wallet hold my funds or private keys during a swap?

No. Axxion Wallet is entirely self-custodial. Your private keys stay locally encrypted on your mobile device or desktop. All token swap interactions occur directly between your self-custody wallet address and the decentralized smart contract protocols on-chain.