Shares of Walmart Inc WMT.N and Marriott International MAR.O fell about 2% after the companies reported quarterly results. By Devik Jain and Shreyashi Sanyal Feb 18 (Reuters) - U.S. stock index futures fell on Thursday as investors resumed a shift out of big technology firms ahead of data that is expected to show a steady recovery in the labor market. Wall Street's main indexes hit record highs at the beginning of the week but gradually retreated following a rise in treasury bond yields, which led to fears of higher inflation.