By Caroline Valetkevitch NEW YORK (Reuters) – U.S. stocks were sharply lower on Tuesday afternoon, with Nasdaq down more than 2%, as a profit warning by Walmart dragged down retail shares and fueled fears about consumer spending. Walmart shares fell 8% after the retailer cut its full-year profit forecast late on Monday. Walmart blamed surging prices for food and fuel, and said it needed to cut prices to pare inventories. Shares of Target Corp declined 3.8% and Amazon.com Inc dropped 5.1%. Also, Amazon said it would raise fees for delivery and streaming service Prime in Europe by up to 43% a ye…