MACD histogram
An MACD-histogram indicates the distance between MACD and its signal line (the   9-period EMA in the MACD). Being an oscillator the   MACD-histogram fluctuates around the zero line.
            
            Traders use the   MACD-histogram to be alerted of imminent signal line crossovers in the MACD. The MACD is   based on moving averages and moving averages lag price. The MACD-histogram does   not have this slight lag. Hence a cross of the zero line by the MACD-histogram   precedes an imminent MACD signal.
            
            This example   shows both the MACD (classic settings 26, 12,9) and the MACD-Histogram.   The vertical dotted lines are to indicate that the cross on the MACD-histogram   happens slightly earlier than the MACD crossover.
          
