Trading

Mean Reversion: Definition

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Simple Definition

The idea that a price which has moved far from its typical level often drifts back toward that average over time. It is a historical tendency, not a guarantee.

Why It Matters

Mean reversion is one of the two big families of trading ideas (the other is trend following). It assumes stretched-out moves tend to snap back toward an average. It's an observed tendency in some markets and time frames, not a law — a price that looks 'too low' can always keep falling. Many algorithmic strategies measure how far price has strayed from a moving average and act on that gap, but the assumption behind them can and does break.

Key Points

  • Assumes extreme moves tend to pull back toward an average
  • A tendency in some conditions, never a guarantee
  • The opposite instinct to trend following

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Common Questions

The idea that a price which has moved far from its typical level often drifts back toward that average over time. It is a historical tendency, not a guarantee. Mean reversion is one of the two big families of trading ideas (the other is trend following). It assumes stretched-out moves tend to snap back toward an average.

Mean reversion is one of the two big families of trading ideas (the other is trend following). It assumes stretched-out moves tend to snap back toward an average. It's an observed tendency in some markets and time frames, not a law — a price that looks 'too low' can always keep falling. Many algorithmic strategies measure how far price has strayed from a moving average and act on that gap, but the assumption behind them can and does break.

Assumes extreme moves tend to pull back toward an average

A tendency in some conditions, never a guarantee

The opposite instinct to trend following