This guide explains how the bands work for mean reversion, the rules, a worked example, the filters that matter most, and how to automate and test the strategy.
At a glance
| Bollinger Band mean reversion | |
|---|---|
| Style | Mean reversion |
| Instruments | Index futures, liquid stocks |
| Timeframe | 5-minute to daily candles |
| Indicator | 20-period moving average with bands at 2 standard deviations |
| Entry | A close below the lower band, then a close back inside |
| Target | The middle band |
| Stop | Beyond the recent low, or a multiple of ATR |
How the bands frame mean reversion
The middle band is a 20-period moving average. The upper and lower bands sit 2 standard deviations away. If prices were normally distributed around the average, about 95% of closes would fall inside the bands. Real prices are not normally distributed, but the bands still show when a move is stretched relative to recent history.
A mean reversion trader reads a close below the lower band as an overreaction and expects the price to return toward the middle band.
The rules
- Range filter. Trade only when the market is not trending strongly, for example when ADX is below 20, or when the middle band is flat.
- Setup. A candle closes below the lower band.
- Entry trigger. The next candle closes back inside the band. This avoids buying while the price is still falling.
- Entry. Buy at the next price.
- Target. Exit at the middle band.
- Stop. Place the stop below the setup candle's low, or at a multiple of ATR below entry.
- Time stop. Exit if the target is not reached within a set number of candles.
The mirror rules apply for selling after a close above the upper band.
A worked example
This is a hypothetical example, not a result.
- On a 15-minute chart of Nifty futures, the middle band is flat at 25,050 and the lower band is at 24,980. ADX is 16, showing no strong trend.
- A candle closes at 24,968, below the lower band.
- The next candle closes at 24,990, back inside.
- The algo buys one lot of 65 at the next price, 24,992. The stop is below the setup candle's low of 24,955, a risk of 37 × 65 = ₹2,405.
- The target is the middle band. The price reaches 25,048 two hours later, where the algo exits for a gain of 56 × 65 = ₹3,640 before costs.
The filters that matter most
Avoid strong trends
The biggest danger is a trend day. When the market falls steadily, the price can "walk the band", closing below the lower band again and again. Buying each close below the band in a downtrend repeatedly catches a falling market. A range filter keeps the strategy out of these days.
Avoid news-driven moves
A gap or a sharp move on news, such as results or policy announcements, can change the fair price. Mean reversion assumes the move was an overreaction; news moves often are not.
Require a turn
Waiting for the close back inside the band costs some of the move but avoids many losing trades.
Bollinger mean reversion vs breakout
The same bands support the opposite trade. After a squeeze, a close outside the band can start a breakout instead of a reversion. Many traders use bandwidth to decide: low bandwidth favours breakouts, normal bandwidth in a flat market favours reversion. See the Bollinger Band breakout strategy.
Position sizing and risk
Mean reversion strategies often win more often than they lose, but a few large losses can wipe out many small wins. Size each trade by the stop distance, using the position size calculator, and cap the number of trades per day.
Related mean reversion strategies
- RSI mean reversion uses momentum extremes instead of volatility bands.
- VWAP mean reversion uses distance from the day's volume-weighted average price.
Automating the strategy
QuantPower's strategy builder lets you set indicator conditions for setup, entry and exit, add filters such as ADX, and attach stops, targets and time limits. Test the rules in the backtesting engine and paper trading first.
Start your free trial
Connect your broker, build a strategy and test it on paper before a single live order goes out.
Backtesting tips
- Split results by market type. Check how the strategy did in trending and range-bound periods separately.
- Test the filter. Compare results with and without the range filter.
- Include costs. Targets at the middle band are often small, so costs matter.
- Fill at the next price after the trigger candle closes.
Frequently asked questions
Is touching the lower Bollinger Band a buy signal?
Not on its own. John Bollinger has noted that a touch of a band is not a signal by itself. Mean reversion strategies add filters and a trigger.
What timeframe works best?
Mean reversion with Bollinger Bands is used from 5-minute to daily charts. Shorter timeframes give more trades with smaller targets, so costs weigh more.
Why does Bollinger mean reversion fail in trends?
Because in a strong trend, the price can keep closing outside the band. A range filter helps avoid those periods.
Sources
- Bollinger, J. (2001). Bollinger on Bollinger Bands. McGraw-Hill
- Wilder, J. W. (1978). New Concepts in Technical Trading Systems. Trend Research (ADX and ATR)