Louisville, Kentucky--Comparable-store sales at U.S. corporate-owned Pizza Hut units dropped 4 percent for the four-week period ended May 17. According to a news release, the results mirror the chain's 4 percent loss in the same period last year. Pizza Hut's parent company, Yum! Brands, does not report sales performance of its franchise stores, which make up approximately 75 percent of its system. -PizzaMarketplace.com