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Bollinger Band


The 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. The Bands expand and contract according to the volatility of the market, with a widening gap indicating increased volatility and a narrowing gap indicating decreased volatility. They are used by traders and investors to define high or low on a relative basis.


The phonetics of the keyword “Bollinger Band” is: ‘Baa-lin-jer Baand’

Key Takeaways

  1. Indicator of Volatility: Bollinger Bands are a technical analysis tool, specifically they are a type of statistical chart characterizing the prices and volatility over time of a financial instrument or commodity. The wider the bands, the greater the volatility. The narrower the bands, the lower the volatility.

  2. Momentum Indicator: The position of the current price relative to the Bollinger Bands can help indicate whether the price is overbought (near the upper band) or oversold (near the lower band). This can help signal potential buying or selling opportunities within the context of an existing trend.

  3. Trend Identification: Bollinger Bands can also be used to identify the start and end of a trend. A breakout beyond the bands followed by a reversal could signal the start of a new trend, while consistent movement along the bands could indicate a strong ongoing trend.


Bollinger Bands are a critical tool in business and finance because they support traders in determining the volatility of the market and potential overbought or oversold conditions. Named after their creator, technical trader John Bollinger, they consist of two price boundaries plotted two standard deviations away from a simple moving average. When the market is volatile, the bands widen, when the market is less volatile, they contract. If the prices are reaching the upper band, the security is potentially overbought, and when they reach the lower band, they are potentially oversold. Thus, Bollinger Bands can guide accurate decisions on when to buy or sell, significantly influencing profitability and risk management in financial trading.


The primary purpose of Bollinger Bands in finance and business is to provide a relative definition of high and low prices of a market. It’s a tool used by traders to measure the volatility of the market and to identify potential buying or selling opportunities. Its bands encapsulate the price movement of a stock, deterring specific boundaries which are in accordance with the volatility levels, thus providing analysts and investors with an overview of the relative market conditions.Bollinger Bands are typically used by traders for three specific purposes: trend trading, reversal trading, and range trading. In trend trading, traders use Bollinger Bands to identify the beginning of a trend and trade in the direction of that trend until the price touches the opposite band. Reversal trading, on the other hand, uses the bands to identify potential points where a trend might reverse, so traders can position themselves for the upcoming change. And lastly, in range trading, traders use Bollinger Bands to indicate a period of low volatility for the market, demonstrating periods where prices are fluctuating within a specific range.


1. Stock Trading: Bollinger Bands are often used in stock trading to identify potential entry and exit points. For instance, if a company’s stock price repeatedly touches the upper band, it may be overbought, indicating a potential selling opportunity because the price may soon fall. Similarly, repeatedly touching the lower band may suggest overselling and a buying opportunity as the price may soon rise. An example of this can be seen in the trading pattern of Apple Inc.’s stocks throughout different market conditions.2. Forex Trading: In a real world application of forex trading, a trader may use Bollinger Bands to decide when to buy or sell a specific currency pair. For example, if the GBP/USD (British Pound to US Dollar) is trading at the lower end of the Bollinger Band, it could be a signal to buy based on the assumption that the pair is oversold and due for a price rally.3. Technical Analysis in Mutual Funds: Bollinger Bands are an effective tool for mutual fund managers to determine the volatility and current prices of different currencies, commodities, and stocks compared to historical data. For instance, a sudden expansion of the bandwidth can be a sign of a big market move. If the fund manager notices the bandwidth beginning to increase after a period of contraction, they may decide to adjust their investments to benefit from the anticipated increased market volatility.

Frequently Asked Questions(FAQ)

What is a Bollinger Band in finance?

A Bollinger Band is a technical analysis tool developed by John Bollinger in the 1980s. It’s a type of statistical chart utilizing a formula which involves a moving average and a set number of standard deviations to plot its bands.

How are Bollinger Bands calculated?

Bollinger Bands consist of three lines: the middle line is a simple moving average (SMA) of the stock’s price, and the two outer lines, or bands, are standard deviations away from the moving average line. Usually, this calculation entails a 20-period SMA with ±2 standard deviations.

What is the utility of Bollinger Bands in trading?

Bollinger Bands are used to measure an asset’s volatility and to identify overbought or oversold market conditions. When the bands tighten, this signals a period of low volatility which often precedes a price breakout. When the bands widen, this indicates intensified market volatility and potential end of a trend.

How do traders interpret Bollinger Band data?

Typically, traders interpret the data as follow: If a stock price repeatedly touches its upper Bollinger Band, the market is considered overbought, while repeated contact with the lower band signals an oversold market. A price movement outside of the bands can signal a continuation of the current trend, while a move that originates within the bands reaching out is likely to reverse the trend.

Can Bollinger Bands be used in all types of markets?

Yes, Bollinger Bands can be applied in all the financial markets including equities, forex, commodities, and futures. This makes them a versatile tool for various types of traders.

Are Bollinger Bands foolproof in predicting price movements?

Like every technical indicator, Bollinger Bands are not 100% accurate and should be used in conjunction with other technical and fundamental analysis tools. Bollinger Bands can show probable price inflection points, but they cannot predict the future.

Related Finance Terms

  • Standard Deviation: This is a statistical measurement that shows how much variation or dispersion there is from the average.
  • Moving Average: This is a widely used indicator in technical analysis that helps smooth out price action by filtering out the “noise” from random price fluctuations.
  • Volatility: This term refers to the statistical measure of the dispersion of returns for a given security or market index.
  • Market Trend: This refers to the perceived direction of financial markets as seen through technical analysis or other statistical methods.
  • Oversold: This is a condition in which the price of a certain asset has fallen sharply, and to a level below its true value. Often, this is an indicator to buy.

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