MACD

Construction

The MACD (after Gerald Appel, 1970s) condenses the relationship of two exponential moving averages into one line: MACD line = EMA(12) − EMA(26). If the fast average sits above the slow one, the line is positive – price has upward momentum. Added to this are the signal line – an EMA(9) of the MACD line – and the histogram, showing the distance between both as bars. The histogram is thus an early indicator within the indicator: it shrinks before the lines cross.

The three classic signals

Signal-line crossover: if the MACD line crosses the signal line from below, that counts as a bullish momentum signal – from above as bearish. In trend phases these crossovers deliver usable entries, in sideways phases they produce many false signals. Zero-line crossover: above zero structural upward momentum prevails (EMA 12 above EMA 26), below zero downward momentum – slower but more robust than the signal-line crossover. Divergences: if price makes a new high but the MACD does not, momentum is fading – a watched but confirmation-requiring warning, similar to the divergence logic of the RSI.

Limits

The MACD is doubly lagging: it is based on moving averages which themselves trail price. In pronounced trends this is unproblematic – in ranges the lines cross constantly and create series of false signals. Many traders therefore combine the MACD with a regime filter (trend vs. range, e.g. via position relative to the EMA 200 or the band width of the Bollinger Bands) and trade MACD signals only in trend direction. As with every indicator: parameters and reading should be backtested for one's own market.

Why it matters for traders

The MACD compactly answers the question “is momentum building or fading?” – as a confirmation tool in trends, not a forecasting instrument. In the GlanWick chart the MACD can be laid over historical data with adjustable parameters and evaluated by way of example – GlanWick is a training and simulation tool and not a prop firm itself.