If you have ever stared at a price chart and wondered if a coin is getting "too expensive" or if a dip is a "bargain," you are asking questions about relative price levels. In the 1980s, a trader named John Bollinger created a tool specifically to answer those questions.
Today, Bollinger Bands are among the most trusted indicators in a trader's toolkit. They do not just show you where the price is; they show you how "loud" the market is being through volatility.
What Exactly Are Bollinger Bands?
Think of Bollinger Bands as a flexible "envelope" that wraps around the price action. They consist of three distinct lines that move together as the market breathes:
- The Middle Band: This is a simple moving average (SMA), usually set to 20 periods. It acts as the "anchor" or the average price of the asset over that time.
- The Upper and Lower Bands: These are plotted two standard deviations away from the middle band. Because they use standard deviation—a mathematical measure of how spread out numbers are—the bands widen and shrink automatically based on market activity.
How to Read the Bands
The magic of this indicator is in its shape. The bands act like rubber bands: the further they are stretched, the more pressure there is for the price to snap back.
1. Forecasting Volatility: The Squeeze
This is the most famous feature of Bollinger Bands. When the market is quiet and the price is moving sideways, the bands contract and move close together. Traders call this The Squeeze.
The Rule: A tight squeeze suggests that the market is "coiling up" like a spring. It usually forecasts a massive breakout. However, the bands only tell you a move is coming, not which direction it will take.
2. Spotting Overbought and Oversold Levels
Since about 90% of price action happens inside the bands, any move outside of them is considered an extreme event.
- Overbought: If the price touches or breaks above the upper band, it is often considered "expensive" relative to its recent average. This might signal a pullback is coming.
- Oversold: If the price touches or falls below the lower band, it is seen as "cheap" or oversold, potentially offering a buying opportunity.
3. Support and Resistance
The bands also act as dynamic barriers.
- In a sideways market, the price tends to "bounce" between the upper and lower bands.
- The Middle Band often acts as a local floor (support) when the price is above it, or a ceiling (resistance) when the price is trying to climb from below.
Pro Tips for Trading with the Bands
While Bollinger Bands are powerful, using them alone is a bit like driving with only one mirror. To trade like a pro, keep these nuances in mind:
- Riding the Bands: In a very strong trend, the price can "walk" up the upper band or down the lower band for a long time. Just because a price touches the upper band does not mean you should sell immediately; the trend might just be very strong.
- Wait for Confirmation: Always pair Bollinger Bands with other tools.
- Lagging Nature: Remember that the bands are based on past data. They react to what the price did, not necessarily what it will do.
Summary
- Tight Bands: Low volatility, expect a big move soon.
- Wide Bands: High volatility, the current trend may be overextended.
- Price at Upper Band: Relatively high/Overbought.
- Price at Lower Band: Relatively low/Oversold.
