MACD compares two exponential moving averages, commonly EMA12 and EMA26. A signal line smooths their difference; EMA9 is a common implementation, while MetaTrader 5’s built-in MACD uses SMA9. A histogram defined as MACD minus the signal shows the distance between those series, although some platforms plot MACD itself as bars. Signal-line crosses, zero-line crosses and price divergences describe relationships in past data. They do not independently prove a change of trend or future acceleration. Specify the calculation, plotted series and decision timing, and test the complete rule with costs.
Example. In a hypothetical GBP/USD H4 scenario, we use EMA12 − EMA26 and an EMA9 signal. MACD crosses above its signal and later above zero: two related readings of the same price series, rather than independent proof of a change in trend. The MACD-minus-signal histogram moves from −0.0008 to +0.0015, showing MACD changing from below its smoother to above it. This does not directly measure price acceleration. Two days later, the lines cross four times within a day of consolidation: an illustration of whipsaw, not a market-wide frequency statistic. Rules, costs and any regime filter, such as ADX, need evaluation. When comparing platforms, check the signal smoother and the meaning of the bars: default periods of 12/26/9 do not imply identical implementations.
Two implementations of the same indicator
An EMA9 and an SMA9 signal can differ despite identical prices and identical EMA12 and EMA26 values. For a manual check, compare numerical values rather than only the appearance of bars. Source for the implementation example: MetaTrader 5: MACD formula and SMA signal.
Two numerical relationships
If EMA12 = 1.1020 and EMA26 = 1.1000, MACD = 0.0020. With Signal = 0.0015, MACD-minus-Signal histogram = 0.0005. This difference crossing zero means equality of the lines; MACD = 0 means equality of the two price averages.
Units and decision timing
MACD has the input price’s units, so readings on differently scaled instruments are not directly comparable. It is neither a percentage return nor a direct second derivative. Specify source, initialisation and completed-bar timing; a later-known signal cannot justify an earlier fill.
FAQ
What does the MACD histogram show?
In a common implementation, H = MACD − Signal. H is zero when the two lines are equal; its zero crossing corresponds to their crossover rather than preceding it. Contracting bars can precede a cross, but do not guarantee one. Some programs, including the built-in MetaTrader MACD, show MACD itself as bars rather than the difference histogram. Check the documentation and buffer values.
How does a signal-line cross differ from a zero-line cross?
A signal-line cross compares MACD with its smoothed value. MACD = 0 means EMA12 = EMA26; positive MACD means EMA12 is higher, and negative MACD means it is lower. These are different relationships, but their order and performance depend on the data and rules. A zero-line cross is not universally slower, stronger or more reliable without a test.
Why can MACD produce losing signals?
Moving averages smooth past data and respond with a delay. Sideways prices can produce repeated crosses, but losses can also occur during trends. A filter such as ADX is another rule to test, rather than a guarantee that false signals disappear.
What are the usual MACD settings?
The popular convention is 12/26/9: two price EMAs and a nine-period signal. State the signal type, such as EMA9 or SMA9; MetaTrader 5’s built-in MACD uses SMA9. Shorter periods commonly increase sensitivity but do not guarantee an edge. Also check the price source, initialisation and whether bars show MACD or MACD − Signal.
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