These alerts appear when a stock prints the tape more quickly than it normally does at this time of day.  They only look at the number of prints, not the size of the prints.  They are focused on timeframes of 3 minutes or less.  This includes all prints, regardless of the exchange or execution venue.

A stock must print at a rate of at least 5 times as fast as normal to generate this alert.  Roughly speaking, if a stock prints as many times in a 3 minute period as it usually does in 15 minutes, then we report an alert.  We can also display additional alerts if the rate continues to rise.

We always compare the current rate of prints to a historical baseline for this stock.  Some stocks typically print more often than others.  And we expect more prints during certain times of day than others.  This historical data is more consistent during regular market hours than in the pre- and post-market.  It is possible to see these alerts in the pre- and post-market, but they are far less common.

These alerts are aimed at finding stocks which are just starting to print quickly; we report these alerts as soon as possible.  However, once we report an alert, we are less likely to report a second alert for the same stock.  If the rate drops, then rises again later in the day, we will display another alert.  And if the rate increases, we will report more alerts. But if the rate remains constant, regardless of how unusual the rate is, you will only see these alerts when this trend starts.  If you wish to see stocks which have been printing more than normal all day long, look at the Strong volume alert or the Min Current Volume filter.

You can filter these alerts based on how much faster the prints are coming in than normal, as described below.