Definition
Liquidity is how easily an asset can be bought or sold quickly without moving its price much. A liquid market has many buyers and sellers, a narrow bid-ask spread and plenty of orders near the current price.
How it works
On an exchange, buyers post bids and sellers post asks at different prices, and together these form the order book. Liquidity shows up in two ways. The spread, the gap between the best bid and the best ask, is narrow. The order book is deep, meaning large amounts are waiting at prices close to the current one. When both are true, a large order can be filled without pushing the price far. In a thin market, the same order uses up the best offers and continues into worse prices, which is called slippage.
Trading volume is related but is not the same thing. Volume counts what has already traded over a period, while liquidity describes what could be traded right now at a reasonable cost. A market can show high volume and still have a thin order book, especially if part of the volume comes from wash trading, where the same party trades with itself.
Liquidity also changes over time. It is usually lower in small coins and stocks, outside main trading hours and during sharp moves, when market makers, traders who keep buy and sell orders posted, may pull their orders. It tends to shrink exactly when many traders want to exit at once, so a market that feels liquid on a calm day may not be liquid in a crash.
Example (hypothetical numbers)
Suppose you want to buy 2,000 units of Coin X and of Coin Y, and both have a midpoint price of $10.00.
Coin X has 5,000 units offered at $10.01, so the whole order fills there: 2,000 × $10.01 = $20,020, which is $20 (0.1%) above 2,000 × $10.00 = $20,000.
Coin Y has only 500 units offered at $10.05, 500 at $10.20 and 1,000 at $10.50: $5,025 + $5,100 + $10,500 = $20,625, an average of about $10.31, roughly 3.1% above the midpoint.
The same order costs $605 more in the thinner market, even though both coins show the same price.
Common mistakes
- Treating high trading volume as proof that a market is liquid.
- Judging liquidity on a calm day and assuming it will still be there during a sharp sell-off.
- Placing a large market order in a thin market without checking the depth of the order book.
Related calculators
This glossary is for education only and is not investment advice. Examples use hypothetical numbers.