Why did my order not execute or was only partially filled?

Most likely, you created a limit order instead of a market order and your order is just waiting in the order book. To understand what’s happening exactly, let’s see how limit orders and market orders work.

How do Limit Orders Work?

Limit orders are orders for which you select a price at which they will be executed, and an amount you want to exchange. When you place a limit order, it is added to the order-book with the orders from other users. It will wait there until someone wants to buy/sell at the price you selected. If there are other orders at a more attractive price than yours, those will be executed first.

For example, consider the following order-book:

The highest bid order (buy) has a price of 1859 Satoshi whereas the lowest ask order (sell) has a price of 1994 Satoshi. If you place a sell order at 1859 Satoshi, it will be executed immediately, provided the amount you selected is smaller than the available bid at that price (281 coins). If you select a higher amount, it will be executed for the maximum available amount of 281 coins, while the rest of the volume creates a new sell order that will be placed in the order book at the price you selected.

As an example, if the order you placed was for 500 coins, 219 coins (500 – 281) will remain in the order book after executing the order for the available 281 coins. Then, when later on someone wants to buy at 1859 Satoshi they will buy the coins from you and you will receive the remaining 219.

If the order to sell you placed has a higher price than 1859 Satoshi, it will be added to the order-book and will have to wait for someone else to want to transact at that price. The same thing would happen if you create an order to buy at any price lower than 1994 Satoshi. This can be useful if you don’t mind waiting and just want to make sure to exchange coins at a specific price.

What are Market Orders?

Market orders make it possible for you to specify the amount you want to buy and buy that amount immediately from the market. This will save you some waiting time, but the prices at which your order is executed will be the ones available in the order book at the time of placing the order. Using the example from before, if you place a market order to buy 1000 coins you will end up buying 6.484 at 1994 Satoshi, 4.495 at 1995 Satoshi, 6.056 at 1997 Satoshi, etc.

Beware of Slippage!

Be very careful when placing market orders. If the amount you select is very large compared to what’s available you might end up overpaying a lot for your coins. For example, consider the following order book:

If you were to place a market sell order for 15000 coins, you would be selling 155.038 coins at a price of 129 Satoshi, 468.740 coins at a price of 128 Satoshi, and so on. Because 15000 coins is too many to sell at once to this market, you would end up selling many of your coins at 76, 73 and 71 Satoshi. That is almost a 50% value loss!

In order to avoid significant value loss when placing a market order, make sure that the volume you want to transact is available in the order book at reasonable prices.