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... when a new high for a stock is accompanied by heavy volume of trading, the market is considered to be bullish. On the other hand, when a new high is associated with light volume, analysts assume that, because there is not much fueling the rally, the increase in price may be a temporary move.

When a new low occurs with light volume, the light volume indicates low investor participation in the stock price drop. This type of drop is not viewed as significant. However, when a new low occurs with heavy volume, many investors are trading at this lower price. The increased volume is seen as fuel for a downward trend in the market and extremely bearish.