Bollinger Bands

Volatility bands plotted above and below a moving average.

Bollinger Bands consist of a moving average with upper and lower bands set a number of standard deviations away. The bands widen when volatility rises and contract when it falls. Prices touching the outer bands may signal overbought or oversold conditions, though not on their own.

The Bollinger Bands squeezed tight, hinting that a big move was coming after the quiet stretch.