U.S. markets tocks started Tuesday trading higher as investors reacted positively to earnings reports. Before the bell, pharmaceutical giants Merck (MRK) and Pfizer (PFE) both reported earnings that beat expectations. Share of United Parcel Service (UPS) fell in early trading after the world's biggest package shipping company reported they missed earnings and cut its guidance. The company says retirement liabilities to Teamster Union employees for the miss. More earnings are expected after the bell including Twitter (TWTR), American Express (AXP) and Aflac (AFL). TheStreet's Susannah Lee reports from Wall Street.