What Is a Fill? Definition in Investing, How It Works, and Types

When an order is executed at the current market price of the security, it is called ‘market fill’. The market fills are designed to be quickly executed and apply only to market orders. The price at which the market order is executed varies due to the fast-moving markets.

To buy or sell securities at a specific price or a more favourable price, a limit order is used. When this limit order is executed, it is called a ‘limit fill’. Since there is a limit to the price, there is no guarantee of the order being executed, as the market needs to reach that specific price.

A stop fill protects traders from losses and helps book profits at predetermined price levels. When the price of securities you hold hits a specific price, the order placed automatically turns into a market order and executes a stop fill.

If you place an order and, due to market liquidity issues or price fluctuations your whole order cannot be fulfilled, then you will receive a partial fill for the quantity that was available at the desired price. The remaining portion of your order will be open to be executed in the future.

In an immediate or cancel order, your order will be immediately executed or cancelled. If a portion of your order is fulfilled, the remaining will be automatically cancelled.

In a fill or kill order, either the entire order is executed or it will be entirely cancelled. There is no partial fulfillment of the order.

In an all or none fill, the entire order needs to be executed at once or not at all.