The MACD indicator (or oscillator) is a collection of three time series calculated from historical price data, most often the closing price. These three series are: the MACD series proper, the signal or average series, and the divergence series which is the difference between the two.he notation MACD(a, b, c) usually denotes the indicator where the MACD series is the difference of EMAs with characteristic times a and b, and the average series is an EMA of the MACD series with characteristic time c. These parameters are usually measured in days.