McDonald's reported better-than-expected global comparable sales in May, boosted by strong results in Asia. The fast food chain reported worldwide sales at restaurants open at least 13 months that rose 0.9 percent last month, beating analyst expectations for a gain of 0.8 percent, according to Thomson Reuters. Same-store sales were strongest in the Asia-Pacific, Middle East and Africa region rose 2.5 percent, far surpassing forecasts of 0.7 percent. The United States, however, continues to be a headwind. Sales in the country fell 1 percent in May. The company hasn't posted a comp sales gain in the U.S. since last October.