Bollinger Bands (BBANDS) Type: Volatility

Bollinger Bands (BBANDS), developed by John A. Bollinger, are set as an envelope around a moving average. Narrow bands indicate a sideways trend (ranging markets). To determine a breakout direction, Investopia.com suggests to use the relative strength index (RSI) along with one or two volume-based indicators such as the intraday intensity index (developed by David Bostian) or the accumulation/distribution index (developed by Larry William).

When the upper and lower bands expand, there can be "M" and "W" formations. The "W" formation indicates a bullish movement and the "M" formation indicates a bearish movement.