Exchanges, Two Designs

Centralized ones run a centralized database with an internal order book, while decentralized ones settle trades on chain after signature from the user. How prices are found in the two systems varies sharply, as do fee structures and the risks that lie in wait. What does all this mean for a newcomer to crypto trading?

Custody and Settlement

On centralized exchanges, you deposit your crypto to exchange-controlled wallets for safekeeping. When you withdraw, the exchange triggers an on-chain transaction to move your crypto to the address of your choice. For structures like this, the clearing happens internally in the exchange database, matching buyer and seller orders off chain. This is part of how centralized exchanges can cost maker and taker fees while keeping the settlement off chain.

Decentralized exchange (DEX) platforms work differently. Instead of holding your crypto in exchange-controlled wallets, you keep it in private custody through a non-custodial wallet. When executing a trade, you sign the transaction from your wallet, and the trade settles against a smart contract on blockchain. Your funds and assets never leave your custody control.

How Prices Are Determined

Centralized exchanges use order books — lists of buy and sell orders at different price points — to match buyers and sellers. They match the top buy order with the top sell order, and price moves upwards or downwards as more orders come in at different levels. This book-building model generates the price you see on centralized exchanges.

DEX platforms clear differently. Most use a system called an automated market maker (AMM). Instead of an order book, an AMM uses a pricing formula to calculate how much of one asset the user gets for every trade — rearranging the amounts of assets in the trading pool to balance buy and sale demand for either. This produces a price that shifts in response to trade demand, not a book of combined offers that trades cut through chronologically. The constant product rule is the pricing formula used by major AMMs.

AMM pricing has two important characteristics for decentralized exchanges. First, the mathematics involved make AMM trading non-linear — the price of a trade is not proportional to the amount of crypto bought or sold, as it would be if you were simply executing a transaction from a bank account. Second, because each trade shifts the balance of assets in the pool, trades can produce noticeable slippage, a term referring to how much the price shifts before the pool finds a new equilibrium. In formal terms, each trader moves the constant product rule to a new tangent. As a result, AMMs produce different market prices in the same way for traders and liquidity providers, adding price predictive risk to the pool. As an informal rule.

What the User Pays

On centralized exchanges, simple maker and taker fees apply to trades, in the range of a few tenths of a percent. Because the settlement happens off-chain in the exchange’s database, no separate on-chain transaction is needed to clear each trade, cutting the costs and delays involved in on-chain settlement.

On decentralized exchanges, each trade is a transaction that gets added to blockchain. As a result, each trade has an on-chain cost associated with it: a small fee to compensate the network for producing the block in which the transaction is verified. That fee adds up across frequent trades, and is an ongoing cost unique to decentralized exchanges. DEX fees also come from liquidity providers, not just from traders. They lend their deposit pools the assets needed to maintain the asset ratios required by the constant product pricing rule. When traders withdraw from the pool and shift the supply-demand equilibrium, the effect is to dilute the value of the remaining assets in the liquidity provider’s pools. This impermanent loss, as it is known, can result in losses for liquidity providers when they withdraw their assets from exchange liquidity pools. Arbitrage from the wider market, not the trade itself, could be the cause of those losses.

The fees on decentralized exchanges have other sources to consider. When a decentralized exchange is built into a blockchain, each trade can carry the risk of an adverse action called maximal extractable value (MEV).

MEV is the value a block producer can extract by including, excluding, or reordering transactions in the block they produce. When a pending order is queued for processing, others in the same block can arbitrage the pending transaction, feeding the gained value back to themselves — at the expense of the trader who started the transaction. A higher transaction fee could decrease the opportunity for separate trading action within the same MEV-affected block.

The Hidden Risks

The fee structures and trading methods picture a different set of considerations for the new user of decentralized versus centralized exchanges. Centralized exchanges are not immune to new forms of market risk, like MEV, but the involvement of a centralized market-maker shorts the main risk channels to the trader.

Decentralized exchanges have no counterparty risk on account of preventing all movements of a user’s assets, since the user determines and executes all actions from a wallet they control. But they face other vulnerabilities, like liquidity providers risking impermanent loss in liquidity pools, and traders bearing slippage in addition to their on-chain transaction costs. On a centralized exchange, the market maker eats these losses instead of traders and liquidity providers, leaving them to argue less about their ETH holdings.

Why This Matters for a Newcomer

Centralized cryptocurrency exchanges run an internal database to settle trades off-chain, while decentralized exchanges let users clear every trade on-chain, signing each one from their own wallet. This means different price formation, fee structures, and trading risks on each type of exchange.

Centralized exchanges are often considered easier to use, with maker and taker fees on trading and no on-chain transactions to track or fees for traders. But decentralized exchanges eliminate counterparty risk, and they offer a risk model closer to trading actual crypto without a central market-maker. Centralized exchanges risk more types of trading hazards for the individual trader, which decentralized exchanges close to trading partners.

The key risk depends from which perspective: decentralized exchanges show shuffle losses from traders and liquidity providers as slippage and impermanent loss, while centralized exchanges absorb the losses to the central market-maker.

Understanding these broad structural differences will help a new trader decide between them. The centralized exchange is likely to meet the newcomer halfway, with clear tools and user support to connect them to the market. The decentralized crypto trading experience will put more knowledge and responsibility on the user, including custody of their own assets on chain, and responsibility in a peer-to-peer network.

Bottom Line

Centralized and decentralized cryptocurrency exchanges have fundamentally different ways of settling trades and grouping transactions. Each handles crypto assets and relies on different models of activity from liquidity provision to asset custody. If a central role is important to you, a centralized exchange will narrow the number of risks to monitor. If you want to skip the counterparty risk and trade directly on chain, the decentralized path has a different set of risks to understand: volatile slippage, persistent transaction fees, and impermanent losses for liquidity providers.

At the end of the day, both can be trustworthy methods of crypto trading, as long as it is reliable and trustworthy for any exchange you select. But interact in ways that influence the prices you trade, and something less tangible: the market information flow captured in each type of exchange. Newcomers will have more depth to find in decentralized exchanges, but also more responsibility, while centralized ones offer the tools and learning frame for someone just starting out.