Volume Analysis
Why trading volume matters and how it's used to confirm price trends.
⏱️ ~6 min read
Key Takeaways
- Volume measures the number of shares (or contracts) traded over a given period
- Rising volume alongside a price move is sometimes interpreted as a sign of stronger conviction behind that move
- Price moves on unusually low volume are sometimes viewed with more skepticism by traders
- Volume is often used to assess whether a breakout from a chart pattern or level is more or less likely to be sustained
What volume measures
Volume refers to the number of shares (for stocks) or contracts (for other instruments) traded during a given period — a day, an hour, a minute, depending on the chart's time frame. It's typically displayed as a bar chart below the price chart, with each bar's height corresponding to the volume for that period.
Volume reflects the level of trading activity and participation — higher volume means more shares changed hands during that period, while lower volume means fewer did.
Volume as a 'confirmation' tool
A common way volume is used is as a way to gauge the 'conviction' behind a price move. A significant price increase accompanied by high volume might be interpreted by some traders as reflecting broad participation and stronger conviction behind the move, compared to a similar price increase on unusually low volume, which might be viewed with more caution — as potentially reflecting less broad-based interest.
Example: Comparing two similar price moves
Stock A rises 5% on a day with volume roughly double its recent average.
Stock B also rises 5% on the same day, but on volume well below its recent average.
Some traders might view Stock A's move as reflecting stronger underlying interest (more shares changed hands to produce that move), while Stock B's move — on lighter volume — might be viewed with somewhat more caution, though neither observation guarantees what happens next.
Volume and breakouts
When a stock's price moves beyond a recognized support or resistance level, or out of a chart pattern (covered in its own lesson), the accompanying volume is often examined. A 'breakout' on high volume is sometimes considered more likely to be sustained, while a breakout on low volume is sometimes viewed as more susceptible to quickly reversing (a 'false breakout').
As always, this is a tendency observed by market participants rather than a guarantee — both high-volume and low-volume breakouts can succeed or fail.
Volume around news events
Volume often spikes around scheduled events like earnings releases, or around unscheduled news. Comparing the volume and price reaction around such events to a stock's typical trading activity can provide context — for example, distinguishing a routine day from one where significant new information appears to have changed how a large number of market participants view the stock.
Volume-based indicators
Some indicators incorporate volume directly into their calculations — for example, On-Balance Volume (OBV) adds volume on up days and subtracts volume on down days, attempting to track whether volume is accumulating in the direction of a trend. Volume-Weighted Average Price (VWAP) calculates an average price weighted by volume at each price level, often used as a benchmark, particularly in intraday trading.
Frequently Asked Questions
Is high volume always 'bullish'?+
No — high volume simply indicates significant trading activity, which can accompany both rising and falling prices. High volume on a down day is generally interpreted differently (often more bearishly) than high volume on an up day.
Why does volume tend to be higher at the market open and close?+
Many orders — including those placed overnight, or by investors and funds executing trades around the daily open and close — tend to concentrate at these times, which is a structural pattern observed across many markets rather than something specific to any individual stock.
Can volume data be misleading for some stocks?+
For very thinly traded stocks, even a relatively small number of shares can represent unusually high volume relative to that stock's norm, and a single large trade can disproportionately affect both volume and price — interpreting volume in context of a stock's typical activity level matters.