MACD: Moving Average Convergence Divergence

What it measures

The MACD line is usually the 12-period EMA minus the 26-period EMA. A 9-period EMA of the MACD line is called the signal line. The histogram shows the gap between those two lines. These are common default settings, not universal best settings.

A short history

Technical analyst Gerald Appel developed MACD in the late 1970s. It made moving-average relationships easier to study as a single line, a signal line and, in many modern charts, a histogram. CMT Association: Gerald Appel

How traders use it

• Study whether short-term momentum is strengthening or weakening.
• Observe MACD and signal-line crossovers as possible changes in momentum, then check price context.
• Use the zero line to see whether the shorter average is above or below the longer average.

A crossover with trend context

This is a study framework for learning and backtesting, not a trade recommendation.

1. Choose a timeframe and define the market direction using price structure or a longer-term average.
2. In an uptrend, study a MACD line crossing above its signal line, especially if the histogram also turns upward. A cross below can be studied in a downtrend.
3. Decide in advance what price level would show the idea is wrong and how much risk is acceptable. A crossover alone is not an entry instruction.

Common mistakes and limits

• MACD is based on moving averages, so it is a lagging tool.
• Frequent crosses in a sideways market can produce repeated false starts.
• Divergence is a warning to investigate, not proof that a reversal will happen.