Overview
MACD is a trend-following momentum indicator developed by Gerald Appel in 1979. It shows the relationship between two exponential moving averages (EMAs) of a security's price and is one of the most widely used indicators in technical analysis.
Three Components
- MACD Line: 12-period EMA minus 26-period EMA. Represents short-term momentum relative to longer-term momentum
- Signal Line: 9-period EMA of the MACD Line. Acts as a trigger for buy/sell signals
- Histogram: MACD Line minus Signal Line. Visualizes the convergence/divergence between the two
Key Signals
- Bullish crossover: MACD Line crosses above Signal Line โ buy signal
- Bearish crossover: MACD Line crosses below Signal Line โ sell signal
- Zero line crossover: MACD crossing above zero confirms uptrend momentum; below zero confirms downtrend
- Divergence: Price makes new highs while MACD makes lower highs โ powerful reversal warning
Strengths
MACD combines trend identification (moving averages) with momentum measurement (crossovers and histogram), making it versatile. The histogram shrinking indicates momentum is fading even before a crossover occurs.
Limitations
As a lagging indicator (based on historical price data), MACD signals often come after a significant portion of a move has already occurred. In choppy, sideways markets, MACD generates many false crossover signals ('whipsaws'). The default 12-26-9 parameters may not suit all timeframes โ intraday traders often use faster settings like 5-13-1.