What is Live Pulse, and how do I read it?

The number

• 60 bpm is a usual minute.
• Under 50 is quiet, 78 and up is busy, 110 and up is racing.
• The bottom row is the whole market (SPY), so you can tell whether it is your stock or everything.

What makes it beat faster

• Bigger candles and more volume than usual over the last eight minutes (the newest count most).
• The busiest times of day: the first hour and the last.
• Price closing in on a level traders watch: VWAP, the day's high or low, today's open, yesterday's high, low or close, an open gap, the 52-week high or low. The dots under the number say which.

With an open trade

Live Pulse is not a buy or sell signal on its own: it tells you how much is happening. Racing into a level, a big move can come fast either way, so have your target and stop ready. Rising from quiet often comes before the move. Quiet for a long stretch, an option you hold loses value to time.

When it updates

Every minute from 9:35 AM to 4:05 PM ET. It climbs or eases a little at a time, so one wild minute does not throw it. The line is the last half hour.