A trendline breakout failure occurs when the price

A trendline breakout failure occurs when the price breaks above a trendline, giving a signal that the existing trend may be changing, but fails to sustain above that breakout level and falls back below the trendline. The concept is important because a breakout alone is not enough; the market needs follow-through buying, sustained closing above the trendline and preferably strong volume to confirm the breakout. When these conditions are missing and price quickly returns below the trendline, it suggests that the breakout was a false breakout, where buyers could not maintain control and sellers regained strength. Such failed breakouts often trap late buyers and can lead to renewed selling pressure.