"BollingerBands" (Financial Indicator)

Commonly abbreviated as BBands or BB.

Is a volatility indicator.

Is computed using the closing price.

Returns three time series consisting of a 20-period moving average of the closing price and bands that are two standard deviations above and below the moving average.

FinancialIndicator["BollingerBands",n,b] uses period n moving averages and bands b standard deviations from the moving average. The first n1 values in the time series are computed using partial periods.