Stocks pulled back a bit in lower volume Wednesday, as investors digested the improved chances that Washington will come to some sort of fiscal agreement. The S&P 500 fell 0.8%, the Dow Jones industrial average dropped 0.7% and the Nasdaq slipped 0.3%. Each of these three indexes had seen a modest gain before heading lower. Volume fell 4% on the Nasdaq and 8% on the NYSE, according to preliminary data. Oracle (ORCL) surged 4% in big volume,