What are Bollinger Bands?
A Bollinger Band is a technical analysis tool defined by a set of trendlines plotted two standard deviations (positively and negatively) away from a simple moving average (SMA) of a security’s price, but which can be adjusted to user preferences.
Bollinger Bands were developed and copyrighted by famous technical trader John Bollinger, designed to discover opportunities that give investors a higher probability of properly identifying when an asset is oversold or overbought.
Bollinger Bands are a technical analysis tool developed by John Bollinger for generating oversold or overbought signals.
There are three lines that compose Bollinger Bands: A simple moving average (middle band) and an upper and lower band.
Day Trading Uptrends With Bollinger Bands
Bollinger Bands can be used to determine how strongly an asset is rising and when it is potentially reversing or losing strength. If an uptrend is strong enough, it will reach the upper band regularly. An uptrend that reaches the upper band indicates that the stock is pushing higher and traders can exploit the opportunity to make a buy decision.
If the price pulls back within the uptrends, and it stays above the middle band and moves back to the upper band, that indicates a lot of strength. Generally, a price in the uptrend should not touch the lower band, and if it does, it is a warning sign for a reverse or that the stock is losing strength.
Most technical traders aim to profit from the strong uptrends before a reversal occurs. Once a stock fails to reach a new peak, traders tend to sell the asset at this point to avoid incurring losses from a reversed trend. Technical traders monitor the behavior of an uptrend to know when it shows strength or weakness, and they use this as an indication of a possible trend reversal.
Limitations of Bollinger Bands
Although Bollinger Bands are helpful tools for technical traders, there are a few limitations that traders should consider before using them. One of these limitations is that Bollinger Bands are primarily reactive, not predictive.
The bands will react to changes in price movements, either uptrends or downtrends, but will not predict prices. In other words, like most technical indicators, Bollinger Bands are a lagging indicator. This is because the tool is based on a simple moving average, which takes the average price of several price bars.
Although traders may use the bands to gauge the trends, they cannot use the tool alone to make price predictions. John Bollinger, the Bollinger Bands’ developer, recommends that traders should use the system along with two or three non-correlated tools that provide more direct market signals.
Another limitation of Bollinger Bands is that the standard settings will not work for all traders. Traders must find settings that allow them to set guidelines for specific stocks that they are trading. If the selected band settings fail to work, traders may alter the settings or use a different tool altogether.
The effectiveness of Bollinger Bands varies from one market to another, and traders may need to adjust the settings even if they are trading the same security over a period of time.