MACD momentum, explained

MACD is built from three pieces: the MACD line (a fast EMA minus a slow EMA, typically 12 minus 26), a signal line (a 9 EMA of the MACD line), and a histogram drawn between the two.

When the fast EMA is above the slow EMA, the MACD line sits above zero — bullish momentum. When it is below, the line sits below zero — bearish momentum.

The two classic events are the cross and the zero-line flip.

A signal cross happens when the MACD line crosses the signal line. In an uptrend a cross back up is read as a pullback buying point; in a downtrend a cross down is read as a continuation. The cross is a lagging event — it confirms momentum, it does not predict it.

When the MACD line crosses zero, the balance of power has actually changed sides between buyers and sellers, not just in the short-term picture.

The histogram is the gap between the MACD line and the signal line. It turns before the lines cross, so a shrinking histogram — while the lines are still apart — is often the earliest hint that momentum is exhausting.

That early warning is what makes the histogram useful: watch for it flattening or shrinking against the direction of the trend.

MACD is built on EMAs of the last few dozen bars — on a delayed or EOD feed the inputs are equally delayed. Signals derived from it are only as current as the data the chart shows. Check the latency badge before acting on an intraday setup.