The short answer
The MACD (Moving Average Convergence Divergence) measures the relationship between two moving averages. The MACD line is the 12-period EMA minus the 26-period EMA; the signal line is a 9-period EMA of that; the histogram is the gap between them. Crossovers hint at momentum shifts, the histogram shows momentum building or fading, and divergence warns a trend is weakening. Like all averages, it lags.
What is the MACD?
The MACD is a momentum-and-trend indicator built from moving averages. At its core it measures how far a fast average has pulled away from a slow one — when they spread apart, momentum is strong; when they converge, it is fading. The standard settings are 12, 26 and 9.
Because it is derived from EMAs, the MACD inherits their strengths and weaknesses: good at describing trend momentum, but always a step behind live price.
The three components
MACD has three parts, and confusion usually comes from not separating them:
- MACD line — the 12-EMA minus the 26-EMA. Above zero means the faster average is higher, i.e. bullish momentum.
- Signal line — a 9-EMA of the MACD line, a smoothed version used to spot turns.
- Histogram — the MACD line minus the signal line, drawn as bars, showing the gap between them.
Crossovers
The classic signal is the MACD line crossing the signal line: up through it is a bullish cue, down through it bearish. The zero-line cross is separate and slower — MACD crossing above zero means the fast EMA has overtaken the slow one, confirming a trend shift.
As with moving-average crossovers, these are late and whipsaw in ranges. They confirm momentum rather than pinpoint entries, and they work far better in the direction of the higher-timeframe trend.
The histogram and momentum
The histogram is often the most useful part. When the bars are growing, the MACD and signal lines are separating and momentum is accelerating; when they are shrinking, momentum is fading even if price is still edging higher.
A histogram that peaks and starts contracting is an early hint that a move is losing steam — earlier than the crossover it eventually produces. It is a momentum gauge, not a trade trigger on its own.
MACD divergence
Like the RSI, the MACD can diverge from price: a higher high in price with a lower high in the MACD warns that the advance is running on weaker momentum. Bullish divergence is the mirror image at lows.
Divergence is a heads-up, not a signal to fade the trend immediately. Combine it with a level and a price trigger, and treat it as a reason to tighten risk, not to reverse on the spot.
Limitations
The MACD is a lagging, average-based tool, so it is late at turns and noisy in sideways markets — you will see crossover after crossover in a range, most of them worthless. It also has no fixed scale, so “high” and “low” readings are relative to the instrument, unlike the RSI's 0–100.
Used well, MACD confirms trend and flags fading momentum. Used badly, it becomes a crossover-chasing machine. Pair it with structure, respect the trend, and size every trade from the stop.
Frequently Asked Questions
What does MACD stand for and measure?
MACD stands for Moving Average Convergence Divergence. It measures the relationship between a fast and a slow moving average to gauge trend momentum — how strongly price is moving and in which direction.
What are the three parts of the MACD?
The MACD line (12-EMA minus 26-EMA), the signal line (a 9-EMA of the MACD line), and the histogram (the difference between the two, drawn as bars).
What is a MACD crossover?
It is when the MACD line crosses the signal line — upward is bullish, downward bearish. The separate zero-line cross is slower and confirms a broader trend shift. Both lag price and whipsaw in ranges.
What does the MACD histogram show?
It shows the gap between the MACD and signal lines. Growing bars mean momentum is accelerating; shrinking bars mean it is fading, which can hint at a slowing move before a crossover occurs.
What is the main limitation of the MACD?
It lags, because it is built from moving averages, so it is late at turns and produces many false crossovers in sideways markets. It also has no fixed scale, so readings are relative to the instrument.