Tick Index

The tick index (symbol: $TICK ) compares the number of stocks that are rising to the number of stocks that are falling on the New York Stock Exchange (NYSE). The index measures stocks making an uptick and subtracts stocks making a downtick. For example, there are roughly 2,800 stocks listed on the NYSE. If 1,800 stocks have made an uptick and 1,000 stocks have made a downtick, the tick index would equal +800 (1,800 – 1,000).  Typically, readings of +1,000 and -1,000 are considered extremes; traders should be mindful of overbought and oversold conditions at these levels. A tick index is a short-term indicator, often only relevant for a few minutes.
(source: Investopedia)