Bollinger Bands: Reading Volatility and Price Extremes
Bollinger Bands expand when markets are volatile and contract when quiet. Learn how to read the squeeze, identify breakouts, use the bands as dynamic support and resistance, and avoid the classic Bollinger Band trap.
Developed by John Bollinger in the 1980s, Bollinger Bands place a volatility envelope around price. The bands automatically widen when the market moves fast and contract when it goes quiet — making them a powerful tool for reading volatility cycles.
The Structure of Bollinger Bands
| Band | Formula | Purpose |
|---|---|---|
| Middle Band | 20-period SMA | Trend direction baseline |
| Upper Band | Middle band + 2 standard deviations | Upper price extreme |
| Lower Band | Middle band − 2 standard deviations | Lower price extreme |
About 95% of all price action falls within the bands. When price moves outside, it is statistically unusual. The bands automatically adjust to current market volatility.
The Bollinger Band Squeeze
The squeeze occurs when bands come very close together, indicating volatility has collapsed to an extreme low. Markets cycle between high and low volatility. After a prolonged squeeze, a large directional move almost always follows.
The Squeeze Does Not Tell You Direction
A squeeze signals that a big move is coming — not which way. Wait for price to break out of the squeeze range and confirm direction before entering.
Walking the Bands in a Strong Trend
In a powerful trend, price can walk along the upper or lower band for an extended period, touching it repeatedly. This is trend strength, not a reversal signal. The classic mistake is shorting every time price hits the upper band.
Touching the Band Is Not a Reversal Signal
In a trend, repeated upper band hits mean momentum. Reserve fading the bands for confirmed sideways, ranging markets only.
Mean Reversion: Playing the Return to the Middle
In ranging markets, price oscillates between the bands and frequently returns to the middle band (20 SMA). When price tags the lower band in a range, a return to the middle is likely — and vice versa.
Range Trading with Bollinger Bands
BankNifty has ranged between 48,000 and 50,500 for three weeks. Price touches the lower band at 48,100. The middle band is at 49,200. A long trade targeting the middle band gives 1,100 points of potential with a tight stop below the lower band.
Combining Bollinger Bands with Other Indicators
- With RSI: lower band touch + RSI below 30 stacks oversold signals for stronger reversal cases
- With MACD: a bullish MACD crossover at the lower band confirms mean reversion entries
- With volume: a breakout from the squeeze on high volume is far more reliable than a low-volume breakout
Key Takeaways
- Bollinger Bands = a 20 SMA with upper and lower bands set 2 standard deviations away.
- Bands widening = increasing volatility; bands narrowing (the squeeze) = breakout incoming.
- Price touching the upper band is not a sell signal in a trend — it signals strength.
- The squeeze sets up a large directional move but does not indicate direction.
- Price tends to return to the middle band (20 SMA) after reaching the outer bands.