Bollinger Bands(redirected from Bollinger band)
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In technical analysis, charts or tables that compare a security's volatility to its price over time. Bollinger Bands? consist of a simple moving average of the security's price over a given number of days (usually 20 or 21), plus one upper limit and one lower limit. The limits are calculated as the amount of the moving average plus or minus two standard deviations. The purpose of Bollinger Bands is to provide a working definition of a security's upper and lower price limit, to indicate if volatility is increasing, decreasing, or staying the same. Bollinger Bands are one of the most popular technical analysis tools. Bollinger Bands are the registered trademark of John Bollinger, who developed them.
The outer limits of the market's price variations that are used by technical analysts to determine if the market is overbought or oversold. The bands are plotted two standard deviations on each side of the moving average. The closer the market average moves to the lower band, the more oversold the market. Conversely, the closer the average to the upper band, the more overbought the market.