Impulse is the most common motive wave. Most impulses contain what Elliott called an extension. An extension is an elongated impulse with exaggerated subdivisions. The vast majority of impulses contain an extension in one and only one of their three actionary subwaves.
- wave 1 must be an impulse or a leading diagonal
- wave 2 can be any corrective pattern except a triangle
- wave 2 must not retrace more than 100% of wave 1
- wave 3 must be an Impulse.
- wave 3 must be longer than wave 2
- wave 4 can be any corrective pattern (zig-zag, double or triple zig-zag, triangle, flat, double or triple three)
- waves 4 must not trade into a territory of a wave 1
- wave 5 must be an impulse or an ending diagonal
- wave 3 must never be the shortest wave when compared to waves 1 and 5.