Four to eight weeks of sideways action in a narrowing range, following a prior advance. Volume declines as the base progresses — the single most important tell. The dips inside the base get shallower: first a 15% pullback, then 8%, then 4%. Each contraction says fewer sellers remain.

A bad base looks different: wide random swings both ways, volume that stays high, and no clear upper edge. That isn't a base but a fight between buyers and sellers, and there's no way to know who wins.

The trigger is a move above the base's upper edge on volume clearly above average — at least one and a half times, preferably double. A breakout on ordinary volume is the number-one cause of failure. The stop sits below the last contraction area, not below the whole base — otherwise the risk is too large and the ratio collapses.

The quieter alternative to a breakout, and often with a better risk/reward: a stock in a clear uptrend drifting down on light volume to its 20- or 50-day moving average, then printing a reversal day. The light volume on the way down is the point — it distinguishes a rest from money leaving.

The advantage: entry sits near support, so the stop is close and the position can be larger at the same risk. The drawback: you're buying while price falls, which demands ignoring the feeling that something is going wrong.