Why Volume is Important
Volume is an important aspect of technical analysis because it is used to confirm trends and chart patterns. Any price movement up or down with relatively high volume is seen as a stronger, more relevant move than a similar move with weak volume. Therefore, if you are looking at a large price movement, you should also examine the volume to see whether it tells the same story.
Say, for example, that a stock jumps 5% in one trading day after being in a long downtrend. Is this a sign of a trend reversal? This is where volume helps traders. If volume is high during the day relative to the average daily volume, it is a sign that the reversal is probably for real. On the other hand, if the volume is below average, there may not be enough conviction to support a true trend reversal.
Volume should move with the trend. If prices are moving in an upward trend, volume should increase (and vice versa). If the previous relationship between volume and price movements starts to deteriorate, it is usually a sign of weakness in the trend. For example, if the stock is in an uptrend but the up trading days are marked with lower volume, it is a sign that the trend is starting to lose its legs and may soon end.
When volume tells a different story, it is a case of divergence, which refers to a contradiction between two different indicators. The simplest example of divergence is a clear upward trend on declining volume.
Volume and Chart Patterns
The other use of volume is to confirm chart patterns. Patterns such as head and shoulders, triangles,flags and other price patterns can be confirmed with volume, a process which we'll describe in more detail later in this tutorial. In most chart patterns, there are several pivotal points that are vital to what the chart is able to convey to chartists. Basically, if the volume is not there to confirm the pivotal moments of a chart pattern, the quality of the signal formed by the pattern is weakened.
Volume Precedes Price
Another important idea in technical analysis is that price is preceded by volume. Volume is closely monitored by technicians and chartists to form ideas on upcoming trend reversals. If volume is starting to decrease in an uptrend, it is usually a sign that the upward run is about to end.
Now that we have a better understanding of some of the important factors of technical analysis, we can move on to charts, which help to identify trading opportunities in prices movements