Stocks are ending slightly lower on Wall Street as investors continue to monitor the run-up to the US presidential election, the AP reports. Earnings were also in focus on Tuesday, and several companies fell after releasing disappointing results or forecasts. Pitney Bowes slumped 19% after its earnings fell short of analysts' estimates, and drugmaker Pfizer fell 2% after its own results didn't meet expectations. The China business of Yum Brands, parent company of KFC and Taco Bell, rose 8% on its first day of trading. The Dow Jones industrial average fell 105 points, or 0.6%, to 18,037. The Standard & Poor's 500 index lost 14 points, or 0.7%, to 2,111. The Nasdaq composite declined 35 points, or 0.7%, to 5,153.