Technicals
MACD
MACD is the gap between a fast and a slow moving average, used to spot changes in momentum.
The moving average convergence divergence takes a 12-period exponential average and subtracts a 26-period one. When the fast average is above the slow one, the MACD is positive and recent prices are stronger than the slightly older trend. A signal line, usually a 9-period average of the MACD itself, gives crossover points that traders treat as momentum shifts.
MACD lags, because every moving average lags. It confirms a move that has started more often than it predicts one that has not. In a range it whipsaws. Read it as a smoothing of the trend, and keep the fundamental view in charge of whether you want to own the business at all.
Formula
MACD = 12-period EMA − 26-period EMA; signal line = 9-period EMA of the MACD
Live example
Apple Inc. (AAPL) last printed at $345.33 with a market cap of $5.04T. Apply the formula on this page to that live price. Where the quote is missing an input, the stock page's financials are the next place to read it.
Related
Moving Averages · Golden Cross · RSI (Relative Strength Index)
See it on a list: best stocks · screener
Questions
What is the histogram?
The histogram is MACD minus the signal line. It shows whether momentum is expanding or fading before the lines cross.
Which settings are standard?
12, 26, and 9 are the published defaults. Changing them without a reason just makes your chart incomparable with everyone else's.