By | September 14 2012 11:26 PM

The Dow Jones Industrial Average (DJI: DJI) gained another 53.51 points, or 0.40 percent, on Friday to close at 13,593.37, the highest level in nearly five years. Recent aggressive efforts in the U.S. and euro zone have cheered investors, but many uncertainties remain. Here are four factors that could make -- or break -- the Dow's continued ascent.