NEW YORK -- Many U.S. retailers are reporting sales declines in May as shoppers continue to shop cautiously.

Costco Wholesale, Hot Topic and Stage Stores are all reporting drops more than analysts expected. However, The Buckle says sales rose above expectations.

Two factors might weigh on May results. A year ago, sales benefited from fiscal stimulus checks. And Wal-Mart Stores Inc., which has recently reported positive results, stopped issuing monthly sales data as of this month. That is likely to hurt overall results. Analysts expect a 4.1 percent drop.

Same-store sales, or sales at stores open at least a year, are a key indicator of retailer performance because they measure growth at existing stores rather than newly opened ones.