The biggest concern is the price of oil, says Jeremy Siegel, Wharton School at The University of Pennsylvania. Of less concern--for now, at least--is the deficit and a government shutdown. Fortunately, says Siegel, the economy is not as sensitive to rising oil as it was in the 70s. But if gas gets above $4, it's going to be a big problem. Also, the reason stocks are where they are right now? Earnings.