Several theories can depict either reversal or pull back or rally sessions.
From technical Analysis:
If major reversal is going to happen,
There should be patterns govern that:
Examples:
Pump and Run Pattern: this Pattern Happen on both Dow and Gold
And I remember that I predict the gold should move down toward 541 and Dow toward 10700.
Head and Shoulders: happened on OLAB and I predicted that OLAB must go back toward 3.5
Sometimes you can have more than one pattern, like both Head and shoulders and bump and run patterns.
How can you say this pump & run pattern or Head and Shoulders?
from my experience, if a share or index went above the 50 and 200 days moving average by almost 40% this means this pattern is fulfilled and market will move back and most often toward the 200 days moving average.
New Theory: Power Low Equations, Applied on Nikkei, and found if the power factor reached unity a share or major index will be like a balloon will burst.
For the pull back market, usually you see only two tops and bottom ( M) shape and once the market make two bottoms and top (W) shape this will move the market back to normal movement. In pull back no major patterns exist (example, Oil).