MACD Explained: Crossovers, the Histogram & the Signal Line
Updated June 25, 2026
MACD (Moving Average Convergence Divergence) is a trend-and-momentum indicator built from moving averages. It shows whether short-term momentum is accelerating or decelerating relative to the longer-term trend.
The three parts of MACD
- MACD line: the 12-period EMA minus the 26-period EMA. When short-term price is pulling above the longer-term average, this rises.
- Signal line: a 9-period EMA of the MACD line — a smoothed version used as a trigger.
- Histogram: the MACD line minus the signal line, drawn as bars. It visualises how fast momentum is shifting.
Crossovers
A bullish crossover happens when the MACD line crosses above the signal line — short-term momentum is turning up relative to the trend. A bearish crossover is the opposite: the MACD line crosses below the signal line. Crossovers near the zero line (where the two EMAs are equal) tend to carry more weight than crossovers far from it.
The histogram gives an earlier read: when its bars stop growing and start shrinking, momentum is fading even before the lines actually cross. A rising histogram confirms strengthening momentum in the crossover's direction.
The whipsaw problem
In choppy, sideways markets MACD generates frequent crossovers that immediately reverse — 'whipsaws' that produce false signals. MACD is at its best confirming a move that other evidence already supports, not as a standalone trigger in a rangebound stock. Pairing it with trend (price relative to the 50- and 200-day moving averages) filters out much of the noise.
In StockTracker AI's scanner, a fresh MACD crossover (within roughly the last five days) is weighted more heavily than a long-sustained state, and it's only one input among several — so a lone crossover in a noisy name doesn't manufacture a high-conviction signal.
Frequently asked questions
What is a MACD bullish crossover?
It's when the MACD line crosses above its signal line, indicating short-term momentum is turning up relative to the longer-term trend. It's most meaningful when it happens near the zero line and is confirmed by a rising histogram.
What does the MACD histogram show?
The histogram is the MACD line minus the signal line. Growing bars mean momentum is accelerating in that direction; shrinking bars mean it's fading — often an earlier warning than the crossover itself.
Is MACD a leading or lagging indicator?
MACD is primarily a lagging indicator because it's built from moving averages, though the histogram has a mild leading quality. Use it to confirm trend and momentum rather than to predict turns on its own.