The MACD indicator is a useful addition to any stock trading strategy. It is a good measure of momentum, trend direction and can also be a good guide to the relative strength of the market, indicating whether the market is overbought or oversold.
However, like all technical indicators there are a number of advantages and disadvantages that any trader should know before incorporating it into their strategy.
Disadvantages
The main disadvantage of the MACD indicator is that it is subjective to the user. Like many technical indicators, the MACD has settings that can be changed to give almost limitless numbers of variations which means results will always differ from person to person.
A trader must decide for example what moving averages to choose. The suggested settings are the 12 day moving average, 26 day and 9, however, these can easily be changed. Secondly, a trader must know what time frame the MACD works best on and there are no easy answers, since the MACD will tend to work differently across different markets. Generally, however, the MACD works best when it is confirmed across several different time frames – especially further out time frames such as the weekly chart.
Lagging indicator
Unless using the divergence strategy (more on this later) which seeks to pick tops and bottoms before they occur, the MACD has an inherent disadvantage that occurs with all technical indicators that concern price history such as moving averages. Since moving averages are lagging indicators, in that they measure the change in a stock price over a period of time (in the past), they tend to be late at giving signals. Often, when a fast moving average crosses over a slower one, the market will have already turned upwards some days ago. When the MACD crossover finally gives a buy signal, it will have already missed some of the gains, and in the worst case scenario it will get whipsawed when the market turns back the other way. The best way to get around this problem is to use longer term charts such as hourly or daily charts (since these tend to have fewer whipsaws). It is also a good idea to use other indicators or time frames to confirm the signals.
The chart below of the Spyders (SPY) clearly shows the lagging nature of the MACD.
While the crossover strategy has the limitation of being a lagging indicator, the divergence strategy has the opposite problem. Namely, it can signal a reversal too early causing the trader to have a number of small losing trades before hitting the big one. The problem arises since a converging or diverging trend does not always lead to a reversal. Indeed, often a market will converge for just a bar or two catching its breath before it picks up momentum again and continues its trend.
MACD divergence and multiple time frames
Actually this is a useful feature of the MACD. Bear in mind the lagging nature of the indicator, looking for divergences between price action and the indicator over multiple time frames makes more sense. In the chart of the SPY above the multiple daily MACD divergences are evident, but prices kept moving higher nevertheless. Prices didn’t break down until 07/25/14 and then corrected for about 5%.
Looking at a weekly chart over the same period, the MACD divergence is evident but only one occurrence is apparent and that occurs at the week ending 07/25/14.
MACD divergence and double tops and bottoms
The multiple timeframe divergence does alleviate some of the whipsaws when using MACD. If we then look at only double tops or bottoms with MACD divergence and multiple time frames, we are effectively using multiple confirmation techniques.
Take the recent top in the market 09/18/14. Prices had reached a new high 09/4/14 then retraced for 7 days before reaching the same peak on 09/18/14. A double top. The chart below shows the MACD indicator clearly diverging as the double top occurs. Prices have corrected over 5% from the peak.
No indicator is foolproof, but combining multiple techniques and time frames does provide greater insight.
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