Volume is the number of shares (or contracts, in futures markets) exchanged during a given time period and is one of the most reliable confirmation tools in technical analysis. The principle is straightforward: price moves on heavy volume reflect genuine conviction from a large number of participants, while the same price move on light volume may lack broad participation and is more likely to reverse. Volume often precedes price — unusually high volume accumulation during flat price action can signal that informed buyers are building positions before a breakout. On breakouts, volume expansion in the direction of the break is strong confirmation; a breakout on thin volume is suspicious. During pullbacks within an uptrend, declining volume is healthy because it suggests sellers are losing commitment, while a pullback on rising volume can indicate distribution by larger holders.
