A trading order that entails an automatic adjustment to the stop buy limit when prices are moving down. It is a conditional order that is based on a trailing amount, rather than a specific stop price, to decide the time to submit a market order. It allows traders to track the price of a security before triggering a market order if the security begins to trade at the trailing stop price.

More specifically, with this buy order, the trade trails the falling price at a fixed distance (the limit). If the limit is reached or exceeded, the buy order will be filled and executed. However, if the price falls, the limit remains unchanged and is not adjusted. This mechanism allows traders to automatically adjust the limit rather than having to constantly track the trade and to adjust the stop buy order based on the price movement and overall performance.