Seriously, looking back does not provide profits tomorrow, and there isn't ever just 1 or 2 reasons why it moved. There are probably hundreds of effects, small and large that contributed, some pushing up, some down, etc.
There are multiple fundamental headwinds that the market is facing. Any single factor alone is not enough to sink the market, but all the factors taken in combination is quite a storm for the indexes to overcome.
Because $&(@ happens that's why!
Really we can say today was red for x number of reasons. High oil prices, October jitters, options expire date, CP going bad. No doubt next week will stink up the joint bad.
Got cash? Got Bear?
