Markets are slightly down today as investors brace for several more weeks of a debt ceiling fight in Washington and retail sales showed that last year's holiday shopping wasn't so bad after all. Dow (INDEXDJX:.DJI) futures fell 0.31% to 13 390. S&P 500 (INDEXSP:.INX) futures dropped 0.40% to 1 458.60. Nasdaq (INDEXNASDAQ:.IXIC) futures slipped 0.29% to 2 720.75. US retail sales in December 2012 beat expectations by a huge margin rising 0.5% after an upwardly revised 0.4% uptick in November 2012. Economists expected a gain of just 0.2%. Excluding autos and gas sales were up 0.6%. Producer prices continue ...