Inflation: Inflationary impulses are rising.
Central Bankers: They are nearly all on a steady and well defined path of tightening.
Mid Term Elections: Recent results in Virginia, Georgia, Pennsylvania and elsewhere suggest that there is a legitimate threat of change in majority in the Senate and/or the House.
Policy Mistakes: Heightened this year as trade tensions (and tail risks) multiply.
Fiscal Policy: The irresponsibility has "left the barn," is set in policy stone and there is no going back.
The President: His actions done on the fly and without comprehensive analysis will have continued unintended consequences - in a flat and interconnected world.
Valuations: Price earnings ratios are still elevated relative to history.
Machines and Algos: It is very doubtful that the tail that wags the dog (quants and leveraged ETFs) will lose their influence in the next few years.
For those that are bearishly inclined I wanted to mention three possible bearish plays which utilize exchange traded funds.
(SDS - Get Report) is a more aggressive play. Its a leveraged short against the S&P Index and if held for more than a few days or a couple of weeks, the tracking error and decay is large and sometimes swift. So I use this ETF as a trading vehicle.