Mean reversion is a trading strategy based on the statistical principle that prices tend to return to their average over time. When prices move significantly above their average, mean reversion traders sell expecting a pullback. When prices drop significantly below average, they buy expecting a bounce. It’s the opposite of momentum trading—betting against extended moves rather than with them.
- Core premise: Extreme moves don’t last; prices revert to the mean
- Buy when oversold, sell when overbought
- Works best in range-bound markets, fails in trending markets
How Mean Reversion Works
Mean reversion exploits the statistical tendency of prices to fluctuate around an average:
Mean Reversion Logic:
1. Calculate the "mean" (moving average)
2. Measure current price vs. mean
3. When price is far above mean → Sell (expect drop)
4. When price is far below mean → Buy (expect rise)
5. Exit when price returns toward mean
The Key: Prices can stay extreme longer than you expect.
Always use stops for when "extended" becomes "new trend."
Quick Reference: Mean Reversion Indicators
| Indicator | Overbought Signal | Oversold Signal |
|---|---|---|
| RSI | Above 70-80 | Below 20-30 |
| Stochastic | Above 80 | Below 20 |
| Bollinger Bands | Price at upper band | Price at lower band |
| Distance from MA | 10%+ above 20-day MA | 10%+ below 20-day MA |
| Z-Score | Above +2 | Below -2 |
Example: A Mean Reversion Trade
Setup: INFY trades at average ₹1,450, suddenly drops to ₹1,320
Day 1: Stock crashes 9% on sector weakness
- RSI: 22 (oversold)
- Price: 3 standard deviations below 20-day MA
- No company-specific news
Entry: Buy at ₹1,325 (mean reversion setup) Stop Loss: ₹1,280 (if new trend, not reversion) Target: ₹1,420 (near 20-day MA)
Day 5: Stock rebounds to ₹1,400 Exit: Sell at ₹1,395
Result:
- Profit: ₹70 per share (5.3%)
- Risk taken: ₹45, Reward earned: ₹70
Mean reversion trading buys oversold conditions and sells overbought conditions, betting prices will return to their average. Use RSI, Bollinger Bands, and moving average distance to identify extreme conditions. This strategy works best in range-bound markets.
Mean Reversion Strategies
1. Bollinger Band Bounce
Buy when price touches the lower band with RSI below 30, sell when price touches the upper band with RSI above 70.
2. RSI Extreme Reversal
Enter when RSI reaches extreme levels (below 20 or above 80) with a reversal candle.
3. Moving Average Distance
Trade when price is 2+ standard deviations from its 20-day moving average.
4. Pairs Mean Reversion
When two correlated stocks diverge from their historical spread, buy the underperformer and short the outperformer.
When Mean Reversion Works (and Doesn’t)
Works Well:
- Range-bound markets
- Liquid, well-followed stocks
- After news-driven overreactions
- In indices and ETFs (harder to change fundamentally)
Fails:
- Strong trending markets
- Fundamental shifts (earnings collapse, new products)
- During sector rotations
- In small caps with real news
The Danger: Catching Falling Knives
Mean reversion’s biggest risk is confusing “oversold” with “broken”:
Oversold (Good for Mean Reversion):
- No fundamental change
- Sector weakness, not company-specific
- Sentiment-driven selloff
Broken (Not Mean Reversion):
- Fundamentals deteriorated
- Company-specific bad news
- Beginning of new downtrend
Key difference: Oversold stocks bounce. Broken stocks keep falling.
Common Mistakes
-
Fighting the trend – In strong trends, “oversold” gets more oversold. Mean reversion is for ranges, not trends.
-
No stop loss – “It has to come back” is how accounts blow up. Always have defined risk.
-
Ignoring fundamentals – A stock that falls 50% on an earnings miss isn’t “oversold”—it’s repriced.
-
Too early entry – Waiting for reversal confirmation (a green candle after reds) improves win rate.
How JournalPlus Tracks Mean Reversion
JournalPlus tracks your mean reversion entries, showing RSI levels at entry, distance from moving averages, and outcome. You can identify your optimal oversold/overbought thresholds for different instruments.
