To simplify the arduous attempt of understanding why markets move focus just on the term of Fear.
Fear is an emotional response to a perceived threat. It is a basic survival mechanism occurring in response to a specific stimulus, such as pain or the threat of danger.
Think of how institutions think. They fear not being in the market when it is going up, as well of fearing being in the market when it is going down.
Have a look at an emerging market index and note its negative bias, US markets have not nearly reacted as much:
Look at US Market in comparison:
Notice as well, emerging markets short through blue lines (support) and the SPX chart is about to blast through?
Yesterday I shorted IBB, MMM.
The major question now is whether institutions fear being in the market? Two weeks ago they feared being out of it.