MACD Explained: Histogram, Signal Line, and Crossovers
Trend direction AND momentum in one indicator.
Researched and written by Laurent The Three Components
MACD was developed by Gerald Appel in the 1970s. Despite its complex-sounding name, it's built entirely from moving averages. Understanding its components makes every signal interpretable:
| Component | Calculation | What It Shows |
|---|---|---|
| MACD Line | 12 EMA − 26 EMA | Whether the fast MA is above/below the slow MA. Positive = bullish. |
| Signal Line | 9 EMA of MACD Line | Smoothed version of MACD. Crossovers signal momentum shifts. |
| Histogram | MACD Line − Signal Line | Gap between the two lines. Growing = momentum increasing. Shrinking = momentum fading. |
Reading MACD Crossovers
The classic MACD signal is when the MACD Line crosses the Signal Line:
- Bullish crossover: MACD Line crosses ABOVE Signal Line. Bullish momentum picking up.
- Bearish crossover: MACD Line crosses BELOW Signal Line. Bearish momentum picking up.
Crossovers above the zero line (positive territory) are considered stronger bullish signals. Crossovers below zero are stronger bearish signals. A bullish crossover that happens when both lines are in negative territory is called a "weak" signal because the overall momentum is still bearish.
Reading the Histogram
The histogram is often more useful than the crossover for timing. Here's the key insight:
- Histogram growing taller: Momentum is increasing in the direction of the signal.
- Histogram shrinking (bars getting shorter): Momentum is weakening. A crossover may be coming.
A trader watching the histogram can anticipate a crossover before it happens: when the bars start shrinking consistently, that's a warning the momentum is fading.
MACD Divergence
Like RSI, MACD divergence is a powerful tool:
- Bearish divergence: Price makes a higher high, MACD histogram makes a lower high. Momentum is declining despite the new high in price. Watch for a reversal.
- Bullish divergence: Price makes a lower low, MACD histogram makes a higher low. Selling momentum is fading. Watch for a reversal upward.
MACD Limitations
MACD is a lagging indicator: all its components are derived from EMAs, which themselves lag price. In choppy, ranging markets, MACD generates frequent false crossovers. Always check the broader trend context before acting on a MACD signal. Is price trending or ranging? If it's ranging, MACD crossovers are noise.
Key Takeaways
- • MACD Line = 12 EMA minus 26 EMA. Positive = faster MA above slower MA (bullish).
- • Signal Line = 9 EMA of the MACD line. Used for crossover signals.
- • Histogram = MACD line minus signal line. Shows momentum strength at a glance.
- • MACD divergence, like RSI divergence, is often more valuable than crossover signals.