Walmart (WMT 0.62%) and Target (TGT 2.80%) are two of the nation's top retailers. But their stocks have been going in opposite directions this year. As of the end of last week, the former was up an impressive 72% while the latter's valuation had fallen by 12%. Despite these businesses being competitors and offering many similar products, the stocks themselves couldn't be more different of late. What's behind the diversion in their performances this year, and is the current trend likely to continue?Two earni ...