A 9-day dotted exponential moving average of the MACD (the "signal line") is also plotted on the top of the MACD (Note: the time period can be adjusted in the box on the top right hand side of the Java Charting System).

When the MACD is above zero, it means the 12-day moving average is higher than the 26-day moving average. This is a bullish signal because it indicates that current expectations are more bullish than previous expectations. When the MACD falls below zero, it means that the 12-day moving average is less than the 26-day moving average, implying that a bearish force makes a shift in the supply/demand lines. The Chart shown as above is a typical example of divergence that appeared when the price was falling but the value of MACD was increasing continuously at the same time. That implied the falling trend should be reversed.