The market hates uncertainty.
And this year we have had more than our share. For instance:
Interest Rates: Will the Fed raise rates? If so when? It appears that December is the time.
Will the dollar strengthen? It seems to be. What does that mean for business and consumers?
Who will win the election? Which candidate will be good for the market? Which candidate will provide stability?
What happens to the price of oil?
What about the conflict in the Middle East?
And so on.