Yesterday, someone asked what MACD is exactly and how to use it effectively, so I thought I’d share my own understanding of this indicator.

Actually, MACD is a very commonly seen indicator on price charts. It was invented in the late 1970s by Gerald Appel. In essence, MACD compares two moving averages to see whether the price trend is strengthening or weakening.

The calculation method is fairly straightforward: subtract the 26-day EMA from the 12-day EMA to get the MACD value. If the value is positive, it indicates the price is in an uptrend; if it’s negative, it indicates a downtrend. As for the Signal Line, it is simply EMA(9) of MACD.

But what’s really important is that using MACD isn’t just about whether it’s positive or negative—you need to look at the slope of the lines. If the MACD line keeps sloping upward, it shows that the uptrend momentum is strengthening. Conversely, if the slope decreases—even if the value is still positive—it could be warning that the trend is starting to weaken.

The most useful part of MACD is that this indicator can tell you when a trend is about to change. You can see this from the points where MACD crosses the Signal Line or crosses the middle line (Central Line). If MACD crosses upward, it’s often a buy signal; if it crosses downward, it’s a sell signal.

That said, MACD is a lagging indicator—it doesn’t predict, it follows price. This means it sends signals later than the actual price changes. Sometimes, when MACD gives a buy signal, the price may have already moved up for some time; and sometimes signals can be wrong, especially in markets that are moving sideways.

The method I like to use is to combine MACD with other indicators, such as RSI or Bollinger Bands, to get more accurate signals. For example, when RSI enters the Oversold zone and MACD crosses upward from the Central Line, there’s a high chance it will be a good buying point. Similarly, if the Bollinger Bands squeeze and MACD signals a change in trend, it is often followed by a significant breakout.

Another thing to know is MACD Divergence, which happens when the price makes a new high but MACD shows a lower value (or vice versa). This signal indicates that the trend may be changing, but it may take some time before it plays out. Therefore, you should wait for confirmation—such as when MACD crosses the Central Line.

In summary, MACD is a good indicator for tracking trends, but it shouldn’t be used on its own. You should combine it with other indicators to reduce mistakes. And most importantly, you need to practice and test your system with a demo account first, so you truly understand the nature of this indicator before using it for real trading.