Stocks edged higher after a rally in retail stocks offset concerns about flaring tensions over increasing the US borrowing limit. Markets were roiled in summer 2011 as lawmakers haggled over the debt limit. The dispute cost the United States its AAA credit rating from Standard and Poor’s. Yet retail stocks moved higher Tuesday, lifted by a Commerce Department report that shoppers spent 0.5% more in December, despite worries about potential tax increases. The S&P 500 and the Dow are up so far this year, having surged after Congress compromised on the fiscal cliff. Optimism about global growth has also boosted stocks.