What is a tick chart? To understand them, consider the conventional chart that draws a new bar after a period of time. It may do this after every five minutes, for example. With a tick chart, on the other hand, it draws a line after a set number of trades instead, such as after every 1000 trades. This is not the NYSE Tick Index, which is a measure of the number of stock issues trading on an uptick versus a downtick. There are many reasons why these charts are best to follow.