MACD
MACD (Moving Average Convergence Divergence) is a trend-following momentum indicator that displays the relationship between two exponential moving averages of a security's price, commonly used to identify historical shifts in the pace and direction of price momentum.
The Moving Average Convergence Divergence indicator was developed by Gerald Appel in the late 1970s and has since become one of the most popular tools in technical analysis. The MACD consists of three components: the MACD line, the signal line, and the histogram.
The MACD line is calculated by subtracting the 26-period exponential moving average (EMA) of the closing price from the 12-period EMA. The signal line is a 9-period EMA of the MACD line itself. The histogram represents the difference between the MACD line and the signal line, making it easier to visualize whether the gap between the two lines is widening or narrowing.
The most studied signal in MACD analysis is the crossover between the MACD line and the signal line. In historical data, periods where the MACD line crossed above the signal line have been observed to coincide with upward momentum acceleration, while crossings below the signal line have historically coincided with momentum deceleration. The zero line crossing — where the MACD line moves from negative to positive territory — marks a historical shift in the relationship between the two underlying EMAs. These historical associations are the basis for technical analysts' interest in the indicator; they are not guarantees of future behavior.
The MACD histogram is used by technicians to observe how the convergence or divergence of the two lines has changed over time. A histogram that has been historically declining even as price continued to rise — a form of divergence — has been studied as potentially indicating that momentum in the price trend was weakening in those historical instances. Whether such observations carry forward-looking implications for any given security is not established by rigorous empirical research.
Because the MACD is derived from EMAs, it is a lagging indicator — meaning it responds to price changes that have already occurred. In trending markets, this characteristic has historically allowed MACD crossover signals to identify established trends. In choppy, range-bound markets, the same lagging nature can produce numerous false signals. Technical analysts often combine MACD with other tools to contextualize its readings within broader price analysis.