The Symmetrical is a new corrective phenomenon discovered by Glenn Neely that is now part of NEoWave (it was discovered long-after Mastering Elliott Wave was written; so, it is not included in the book).
According to Glenn Neely's Q&A discussions, Symmetricals were developed to explain market formations that:
These structures reflect prolonged periods where buyers and sellers remain relatively balanced before a directional resolution eventually develops.
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