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Exhaustion Gaps
Exhaustion gaps are those that happen near the end of a good up- or downtrend. They are many times the first signal of the end of that move. They are identified by high volume and large price difference between the previous day's close and the new opening price. They can easily be mistaken for runaway gaps if one does not notice the exceptionally high volume.
It is almost a state of panic if the gap appears during a long down move where pessimism has set in. Selling all positions to liquidate holdings in the market is not uncommon. Exhaustion gaps are quickly filled as prices reverse their trend.