Mean reversion is a concept in finance that suggests prices tend to return to their historical average over time. It’s like gravity for markets, when prices drift too far from their “normal,” they often snap back.
The “Mean” is the average price of an asset over a certain period, like a 50-day or 200-day moving average. Reversion is when a stock trades significantly above or below this average, traders expect it to eventually move back toward that mean.
Overreactions to news, earnings, or macro events can cause mean reversion by pushing prices too far. Once the dust settles, prices often normalize.
Mean Reversion Example
Let’s say ABC Company has a 30-day average price of $4.50, but it spikes to $6.00 after a news event. A mean reversion trader might:
- Short the stock or buy a put spread, expecting it to drift back toward $4.50.
- Use tools like Bollinger Bands, RSI, or moving averages to identify when the price is stretched.
When Mean Reversion is Useful
- Range-bound markets: Works best when there’s no strong trend.
- Volatility spikes: After big moves, reversion setups can offer high-probability entries.
- Options strategies: Great for structures like iron condors, butterflies, or gamma-locked ladders, where you want price to “settle down.”
Mean Reversion Strategic Frameworks
Since we are already weaving mean reversion into butterfly and gamma-locked ladder setups, let’s break down some strategic frameworks that go beyond the basics.
Classic Mean Reversion with Bollinger Bands
- Setup: Identify when price closes outside the upper or lower Bollinger Band.
- Trigger: Enter when price re-enters the band, signaling a potential snapback.
- Example: ABC Company closes above the upper band on a news spike, short or buy a put spread expecting a drift back toward the 20-day moving average.
RSI Fade Strategy
- Setup: Use RSI > 70 (overbought) or < 30 (oversold) as a signal.
- Trigger: Enter when RSI crosses back below 70 or above 30.
- Enhancement: Combine with volume divergence or candlestick reversal patterns for confirmation.
Pairs Trading (Statistical Arbitrage)
- Setup: Find two correlated stocks (e.g., $BTBT and $MARA).
- Trigger: When the spread between them widens beyond historical norms, short the outperformer and long the underperformer.
- Why it works: It quantifies how extreme the move is in standard deviation terms, great for backtesting.
