Bollinger Band means a band plotted two standard deviations away from a simple moving average.
Since standard deviation is a measure of volatility, Bollinger bands regulate themselves to the market conditions. When the markets become more volatile, the bands widen (move further away from the average), and in less volatile periods, the bands contract (move closer to the average). The tightening of the bands is frequently used by technical traders as an early sign that volatility is about to increase strongly.
The nearer the prices move to the upper band, the more overbought the market, and the nearer the prices move to the lower band, the more oversold the market.
Bollinger recommends using a 20-day simple moving average for the center band and 2 standard deviations for the outer bands.
Trial and error is one way to determine an appropriate moving average length. A simple visual judgment can be used to determine the suitable number of periods. Bollinger Bands should encompass the majority of price action, but not all of it. After sharp moves, penetration of the bands is normal. If prices appear to penetrate the outer bands too regularly, then a longer moving average may be necessary. If prices rarely reach the outer bands, then a shorter moving average may be necessary.
Sharp price changes are known to happen after the bands have tightened and volatility is low. Investors should keep in mind that Bollinger Bands do not give any clue to future direction of prices. Direction must be determined using other indicators and aspects of technical analysis.
Even though Bollinger Bands can assist in generating buy and sell signals, they are not intended to determine the future direction of a stock. The bands were designed to augment other analysis techniques and indicators.
The Bollinger Bands indicator for this stock is currently showing a bullish reading. The bullish reading may have been triggered for this stock because it resembled signs of a double bottom buy signal. A Double Bottom Buy signal is given when prices penetrate the lower band and continue above the lower band after a subsequent low forms. Either low can be higher or lower than the other. The important thing is that the second low continues to stay above the lower band. The bullish setup is confirmed when the price moves above the middle band, or simple moving average. The Bullish reading may also have been triggered because the closer prices move to the lower band for this stock, the more oversold the market. Sharp price changes are known to happen after the bands have tightened and volatility is low. That being said, investors should keep in mind that Bollinger Bands usually do not give any clue to future direction of prices. Direction must be determined using other indicators and aspects of technical analysis. BullishInvestor.com encourages investors to view a Bollinger bands chart for signs of where this stock may be heading.