The MACD Histogram gives depth and dimension to what the MACD lines are telling you. The MACD histogram is based on the difference between two moving averages, typically a 12 period moving average and 26 period moving average. a typical MACD histogram is made up of two parts. The first is a graph with the 12 and 26 period moving average and the second is the difference between these two moving averages giving rise to the histogram. When the fast moving average is greater than the slower moving average, the trend is up. When the slower moving average is above the faster moving average, the trend is down.

The MACD Histogram indicator graph is the bottom graph.

Do you see that hump at the end of February and the cross of the histogram below the trigger line? That's a bearish development. Why? Because prices have not moved higher while the indicator has. The high level of the indicator at the end of February and the fact that the prices have not made new highs shows that CTAS is about the change in trend to the down side.

There are red bars and green bars on this MACD histogram. The bars change from green to red when the trigger line crosses the histogram. One important fact to keep in mind when reading this indicator is the size of the bars. When the bars have been getting larger (or smaller) there comes a point when two or three bars are of equal size. This is a classic condition of when the trend is about to change. This is not a totally infallible situation but it is a good indication of what might be ahead for this stock.