What it is
MACD — Moving Average Convergence Divergence — is a trend-following momentum indicator that shows the relationship between two moving averages of price. It helps traders identify trend direction, momentum, and potential entry and exit points.
MACD was developed by Gerald Appel in the late 1970s and is one of the most popular indicators in technical analysis. It appears by default in MetaTrader and is widely used as a component in EA strategies.
How it works
The MACD consists of three components:
- MACD line: The difference between a 12-period EMA (Exponential Moving Average) and a 26-period EMA. This line oscillates above and below zero.
- Signal line: A 9-period EMA of the MACD line itself. This smooths the MACD to generate cleaner signals.
- Histogram: The difference between the MACD line and the signal line, shown as vertical bars. Positive bars (MACD above signal) indicate bullish momentum; negative bars indicate bearish momentum.
The three main signals
- Signal line crossover: MACD crossing above the signal line is bullish; crossing below is bearish. This is the most common MACD signal.
- Zero line crossover: MACD crossing above zero confirms an uptrend; below zero confirms a downtrend.
- Divergence: Price makes a new high but MACD makes a lower high — momentum is weakening despite rising price, suggesting a potential reversal.
Why it matters
MACD combines trend direction (the position of the MACD line relative to zero) with momentum (the distance between the MACD and signal lines) in a single indicator. This dual nature makes it useful both for identifying trend direction and for timing entries within that trend.
In EAs, MACD is often used as a filter — confirming that a trade is in the direction of the current momentum before executing. An EA might only buy when MACD is above zero (uptrend) and the histogram is rising (momentum increasing).
Common misconceptions
- MACD is a lagging indicator. Because it's based on moving averages, MACD signals come after price has already started moving. It confirms trends rather than predicting them. Don't expect MACD to catch the very start of a move.
- Divergence doesn't always lead to reversal. MACD divergence is a warning sign, not a guarantee. Price can continue in the original direction for a long time after divergence appears.
The Karnek note
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Written and reviewed by the Karnek Research team. Last updated August 2026.
Educational content only - not financial advice. Past performance does not predict future results. Trading carries significant risk.