A diagonal triangle is a motive pattern yet not an impulse, as it has one or two corrective characteristics. Diagonal triangles substitute for impulses at specific locations in the wave structure. As with impulses, no reactionary subwave fully retraces the preceding actionary subwave, and the third subwave is never the shortest. However, diagonal triangles are the only five-wave structures in the direction of the main trend within which wave four almost always moves into the price territory of (i.e., overlaps) wave one. On rare occasions, a diagonal triangle may end in a truncation, although in our experience such truncations occur only by the slimmest of margins.
An ending diagonal is a special type of wave that occurs primarily in the fifth wave position at times when the preceding move has gone “too far too fast,” as Elliott put it. A very small percentage of ending diagonals appear in the C wave position of A-B-C formations. In double or triple threes (to be covered in Lesson 9), they appear only as the final “C” wave. In all cases, they are found at the termination points of larger patterns, indicating exhaustion of the larger movement.
Ending diagonals take a wedge shape within two converging lines, with each subwave, including waves 1, 3 and 5, subdividing into a “three,” which is otherwise a corrective wave phenomenon. The ending diagonal is illustrated in Figures 1-15 and 1-16 and shown in its typical position in larger impulse waves.
We have found one case in which the pattern’s boundary lines diverged, creating an expanding wedge rather than a contracting one. However, it is unsatisfying analytically in that its third wave was the shortest actionary wave, the entire formation was larger than normal, and another interpretation was possible, if not attractive. For these reasons, we do not include it as a valid variation.