This screen finds the first three waves of an upward Elliott impulse: an advance, a pullback, and a third advance. Elliott Wave theory, developed by Ralph Nelson Elliott, holds that trends move in five impulse waves in the direction of the trend, followed by three corrective waves, labeled A, B and C. Here the waves are taken from ZigZag swings, which filter out minor price moves. Wave three is often the strongest and longest, so stocks in it may be in the most powerful part of the uptrend.