Downtick

A downtick is a transaction that occurs at a lower price than the previous trade for a given security. A downtick is sometimes called a minus tick. The opposite of a downtick is an uptick. A zero downtick is not actually a downtick, but is a trade that occurs at the same price as the prior transaction in the case where that prior trade was a downtick. The zero downtick is sometimes called a zero-minus tick. The opposite of the zero downtick is the zero uptick. One context when the downtick is important is when trading curbs are in effect. For example, the NYSE prohibits program trade sell orders on a downtick if the market is down by a certain amount for the day.