Dip or Peak
Mean reversionIntermediate

Bollinger band reversion: buying the snap back inside

A close below the lower Bollinger band followed by a close back inside can mark a stretched move turning. How to trade it and when the band keeps walking down.

· 4 min read

Bollinger band reversionA candle closes below the lower Bollinger band and the next closes back inside. The target is the middle band. Upper band Lower band Middle: target Stop Closes outside Buy
Price with upper, middle and lower Bollinger bands: one candle closes below the lower band, the next closes back inside, and the target is the middle band. Illustration with simulated prices.

Key takeaways

  • Wait for a close back inside the lower band, not just a close below it.
  • Skip the setup when the bigger timeframe is trending down.
  • Target the middle band, and check it is far enough away to pay 1.5 R after fees.
In this article
  1. How it works
  2. The rules, precisely
  3. What to check

Bollinger band reversion buys after price has stretched unusually far below its recent average and then starts to come back. The idea is that extreme moves tend to relax toward the middle. Traders like it because it gives a clear trigger, a nearby stop and a natural target.

How it works

Bollinger bands are three lines around price. The middle band is a moving average: the average close over recent candles, typically 20. The upper and lower bands sit two standard deviations above and below it. A standard deviation measures how spread out recent closes have been. When the market is calm the bands are close together. When it is volatile they widen.

Because the bands adjust to volatility, a close below the lower band means price is unusually low compared to how it has been moving lately. That can happen for two reasons. Sometimes it is a short overreaction: a burst of selling, stops being hit, then a recovery. Sometimes it is the start of a real move, and price “walks the band”, closing at or below the lower band candle after candle.

This setup tries to separate the two by waiting. It does not buy the candle that closes below the band. It buys the next candle, only if that one closes back inside. A close back inside is the first evidence that the stretch is easing.

It also checks the bigger timeframe: the next chart up (1 hour if you trade 15-minute candles, 4 hours for 1-hour, daily for 4-hour). That chart is “trending down” when its close is below its 20 EMA and the 20 EMA is below the 50 EMA. An EMA (exponential moving average) is an average of recent closes that weights the newest ones more. When the bigger chart is trending down, closes below the lower band are more often the trend continuing than an overreaction.

The rules, precisely

Here is one precise, testable version of this strategy. Traders vary these numbers. It is written for a long. The short is the mirror image at the upper band.

  1. Lower bandcloses below the bandThe candle before ✓
    The stretch: the candle before closed below the lower Bollinger band.
  2. Lower bandcloses back insideThis candle ✓
    The snap back: this candle closed back inside the band (above the lower band).
  3. Bigger timeframeUp ✓Flat ✓Down ✕
    Context: the bigger timeframe is not trending down.
  4. Entry: the closenot the next candleEnter once the candle has closed ✓
    Entry: at the close of this candle.
  5. 0.2 ATRLower low of 2StopStop just past the structure ✓
    Stop: below the lower low of the last 2 candles, minus 0.2 ATR (average true range, the typical size of a recent candle).
  6. 1R≥ 1.5RMiddle bandStopTarget 1 at least 1.5R away ✓
    Target 1: the middle band.

Where it works

  • Ranges and gently rising markets, where sharp dips tend to be bought.
  • Sudden one or two candle flushes, such as a wave of liquidations, that recover quickly.
  • When the bands are reasonably wide, so the middle band is far enough to pay.
  • When the dip lands on a level that mattered before.

Where it fails

  • Fresh breakdowns, where price walks down the lower band and the close back inside is brief.
  • Very quiet markets with narrow bands, where the middle band is too close for 1.5 R.
  • News-driven drops that change what the coin is worth.
  • Short timeframes with tight stops, where fees take a large share of R.

What to check

  1. Were the bands squeezed before the drop? If the bands were very narrow and then the lower one opens sharply, the break may be the start of a new move rather than an overreaction. Reversion setups out of a squeeze deserve extra caution. The squeeze breakout article covers trading that move instead.
  2. Is the middle band far enough away? Measure the distance from entry to the middle band in R. If it is under 1.5 R, skip the trade. Note that the middle band moves: if price keeps falling, the target falls with it.
  3. Is there a level under the dip? A dip below the band that also tags a prior swing low, the previous day's low or the value area low is more likely to bounce than one into empty space.
  4. What caused the drop? A liquidation flush on no news is the classic overreaction. A drop on a hack, a delisting or a large token unlock is not, and bands cannot tell the difference.
  5. How strong is the close back inside? A close barely above the lower band with a long upper wick shows hesitant buyers. A close well inside the band, near the candle's high, shows more conviction.
  6. Is the bigger chart flat or rising? The rule only excludes a downtrend. A clear uptrend on the bigger chart gives dips more support than a flat one.
  7. Do fees fit? On 15-minute candles the 2-candle low may be very close. Check that round-trip fees cost no more than 0.3 R.

Price closing outside a band is not rare and not a signal on its own. Whether this rule set has any edge depends on the coin and timeframe, so backtest it with fees on recent history first. None of these rules is known to make money.

Stops, targets and the time limit work the same way for every setup in this series. See managing a setup: stops, targets and the time limit.

Keep reading