What are price gaps?

A price gap occurs when a stock's price makes a sharp move up or down with no trading occurring in between. It can happen because of factors like earnings announcements, a change in an analyst's outlook, or a news release. Gaps frequently occur when exchanges open or when news or events outside of trading hours have created an imbalance in supply and demand.

Stop orders and price gaps

Remember that the key difference between a limit order and a stop order is that the limit order will only be filled at the specified limit price or better; whereas, once a stop order triggers at the specified price, it will be filled at the prevailing price in the market—which means it could be executed at a price significantly different than the stop price.

What is a stop limit order?

Another order type combines a stop order and a limit order. The stop limit order specifies the price that the order should be triggered and the price that the trader wants to execute the trade. It gives the trader a traditional stop order, but once triggered, a limit order at their specified price instead of a market order. While the trader might prefer to sell at their limit price, execution isn't guaranteed, and the trader has risk of the stock moving lower after triggering.

The chart below shows a stock that "gapped down" from more than $34 to around $32 between a previous closing price and the next opening price. A stop order to sell at a stop price of $34—which would trigger at the market's open because the stock's price fell below the stop price and, as a market order, executes at $32—could be significantly lower than intended, and worse for the seller. In the case of a stop limit order with the stop set at $34 and the limit at $33, for example, the trader could be watching the stock trade lower and "hoping" or "waiting" for the stock to return to $33 before being executed.

Stop order: Gaps down can result in an unexpected lower price.