Elliott Wave Theory
Elliott Wave Theory describes markets as alternating between five waves in the direction of the trend and three corrective waves.
Ralph Nelson Elliott set it out in the 1930s. An impulse has five waves (1 to 5), followed by a three-wave correction (A, B, C). Each wave breaks down into smaller-degree waves.
Three rules are strict: wave 2 never retraces more than 100% of wave 1, wave 3 is never the shortest of waves 1, 3 and 5, and wave 4 does not enter wave 1's territory (special cases aside).
Its big limitation is subjectivity: two analysts can count the same chart differently. Use it as a reading framework, with precise invalidation levels.