Stocks were mixed on Tuesday morning following earnings reports from major retailers and new housing market data. Walmart shares rose 2% after the company reported better-than-expected 1Q sales and earnings and raised its full-year guidance. Macy's shares also rose following an unexpected first-quarter profit. The Commerce Department said that U.S. housing starts fell 9.5% to a seasonally adjusted annual rate of 1.569 million units in April, down from 1.733 million in March and below the Reuters consensus