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Understanding bollinger bands

Understanding bollinger bands


30th November 2019
Updated: 9th September 2020

What are Bollinger Bands?

A Bollinger Band is a technical analysis indicator used to measure market volatility. Simply put, the indicator tells whether the market is in a period of low or high volatility, depending on the size of the bands and how prices oscillate.

A Bollinger band primarily consists of a set of lines plotted from a simple moving average that can be adjusted to fit any trading strategy.  The standard deviation aspect is the measure of volatility in the bands. 

For instance, whenever the market is highly volatile, then the bands would widen and narrow whenever the market is less volatile. Bollinger bands show levels of highs and lows when it comes to price action.

The Bollinger Bounce

The Bollinger Bounce is an aspect of Bollinger Bands whereby price tends to move to the middle of bands from time to time. By looking at the chart above, it is clear that price had the tendency to move to the middle of the bands on its way to the topmost or lowermost level of the band.

The bounce occurs because the Bollinger bands act as levels of support and resistance from which traders enter and exit positions, triggering price movements. The highest level of a Bollinger band is often seen as a statistically high or expensive level, which prompts traders to exit positions. Conversely, the lower band is often seen as a low or cheap level, consequently attracting buy orders.

The bounce that occurs at the bands has made Bollinger bands ideal trading indicators for range-bound markets.

Bollinger Squeeze

In addition to being effective in range-bound markets, Bollinger Bands also find great use in trending markets. The Bollinger Squeeze refers to the narrowing of Bollinger bands, signalling a potential breakout on the horizon.

Whenever the bands constrict and come close to each other, it is always indicative of low volatility, signalling potential future build up in volatility. The wider apart the bands are, the likelihood is that volatility decreases after some time on traders exiting positions after a spike.

After the narrowing of the Bollinger bands, whenever candlesticks start to break out above the topmost band, then the price of the underlying asset will most of the time head higher. Conversely, whenever candlesticks start to break out below the bottom band, then the price will usually edge lower, indicating the formation of a downtrend.

Breakouts above or below Bollinger Bands occur from time to time, mostly as a result of a major event. While the breakouts are always indicative of strength in a given direction, they should never be relied upon as trading signals. A breakout could trigger oversold or overbought situations whereby price could bounce back or collapse afterward.

In addition, whenever new highs and lows are made outside the Bollinger Bands, followed by highs and lows inside the bands, that could signal a potential reversal on the prevailing trend.

Bottom line

Bollinger Bands, just like any other indicator, should never be used independently. The fact that they provide information about the level of volatility in the market means they should always be used with other indicators in a trading strategy. Some of the indicators that one can use in tandem with Bollinger Bands include the Moving Average Divergence and Convergence indicator, or Relative Strength Index.

By Harry Atkins
Harry joined us in 2019 to lead our Editorial Team. Drawing on more than a decade writing, editing and managing high-profile content for blue chip companies, Harry’s considerable experience in the finance sector encompasses work for high street and investment banks, insurance companies and trading platforms.
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