






Introduction
When you buy and sell assets on a crypto exchange, the market prices are directly related to supply and demand. Apart from the price, other important factors to consider are trading volume, market liquidity, and order types. Depending on the market conditions and the order types you use, you won’t always get the price you want for a trade.
There is a constant negotiation between buyers and sellers that creates a spread between the two sides (bid-ask spread). Depending on the amount of an asset you want to trade and its volatility, you might also encounter slippage (more on this later). So to avoid any surprises, getting some basic knowledge of an exchange’s order book will go a long way.
What Is Bid-Ask Spread?
The bid-ask spread is the difference between the highest bid price and the lowest ask price of an order book. In traditional markets, the spread is often created by the market makers or broker liquidity providers. In crypto markets, the spread is a result of the difference between limit orders from buyers and sellers.
If you want to make an instant purchase, you need to accept the lowest ask price from a seller. If you’d like to make an instant sale, you’ll take the highest bid price from a buyer.
More liquid assets (like forex) have a narrower bid-ask spread, meaning buyers and sellers can execute their orders without causing significant changes in an asset’s price. This is due to a large volume of orders in the order book. A wider bid-ask spread will have more substantial price fluctuations when closing large volume orders.
Market Makers and Bid-Ask Spread
The concept of liquidity is essential to financial markets. If you try to trade on low-liquidity markets, you might find yourself waiting for a while until another trader matches your order.
Creating liquidity is important, but not all markets have enough liquidity from individual traders alone. In traditional markets, for example, brokers and market makers provide liquidity in return for arbitrage profits.
A market maker can take advantage of a bid-ask spread simply by buying and selling an asset simultaneously. By selling at the higher ask price and buying at the lower bid price over and over, market makers can take the spread as arbitrage profit. Even a small spread can provide significant profits if traded in a large quantity all day. Assets in high demand have smaller spreads as market makers compete and narrow the spread.
For example, a market maker may simultaneously offer to purchase BNB for $800 per coin and sell BNB for $801, creating a $1 spread. Anyone who wants to trade instantly in the market will have to meet their positions. The spread is now arbitrage profit for the market maker who sells what they buy and buys what they sell.
Depth Charts and Bid-Ask Spread
Let’s take a look at some real-world cryptocurrency examples and the relationship between volume, liquidity, and bid-ask spread. In Binance’s exchange UI, you can easily see the bid-ask spread by switching to the [Depth] chart view. This button is in the upper-right corner of the chart