The U.S. market will not and cannot go down. See the other ET threads on the Plunge Protection Team. They are real. It's codified into federal law.
Who in the world would want to be short? When you find the most powerful financial entity on the planet supporting a market, or working it in a certain direction, you *join* it. Riding the coattails of a big player who's rigging a market, is the best thing you can hope for in your trading life.
Shorting is like going to the highway, and waiting til you're certain you've seen the biggest truck and then going to the road to stand in front of it. Makes no sense whatsoever.