Average Volume

Average volume is the baseline. "Above average" only means something once you say which average. A 20-day average includes a recent event. A 50-day average dilutes it. Neither is the "true" liquidity of the stock. They are two windows. Reported average volume on a stat page is often a daily share count, which is the wrong baseline for a volume bar at 10:15.

Divide today's volume by the average to see the multiple. Two times average is active. Five times average is an event, a rebalance, or a bad print. Check the corporate calendar before you build a story. Average volume also sets a liquidity floor: a name that averages a few hundred shares a day cannot absorb a market order the way its chart pattern suggests.

Use the average as the denominator for relative volume and as a screen for tradable names. Use a rising average, not one spike, to see whether the market is genuinely more active in this name. When you size a position, the average daily volume is a crude capacity check. A position that is a large fraction of a day's volume will be the volume when you exit.

Using a 5-day average that is dominated by one earnings bar and then calling a normal day "light." Also treating average volume as a forecast of today's volume. It is a mean of the past, and volume distributions are skewed by those event bars.

The average hides the shape of the day. A stock can print its whole average in the first fifteen minutes and then die. And after a split the unadjusted history will show a fake collapse in volume unless the series is adjusted.