A breakdown failure occurs when a stock moves below an important support level (such as a trendline, range low, or swing low) but fails to sustain below it and quickly reverses back above that level. This indicates that selling pressure was not strong enough and buyers have stepped in aggressively, trapping short sellers who entered on the breakdown. As these trapped sellers exit their positions, it adds further buying pressure, often leading to a sharp upward move. Breakdown failures are considered bullish signals, especially when accompanied by strong volume and quick price recovery above the support zone.