A plus tick (uptick) that occurs when the execution price is the same as the previous trade, but higher than the most recent trade at a different price.

For example, if a series of trades takes place at $25.02, $25.05, and $25.05, the last trade (or tick) is the zero plus tick because it executed at a price equal to that of the previous trade, but higher than the preceding tick of $25.02.

The reverse of a zero plus tick (zero uptick) is a zero minus tick (zero downtick).