Walgreen same-store sales rise 0.9 pct in August

Same-store sales, or sales at stores open at least a year, is a key indicator of retailer performance since it measures growth at existing stores rather than newly opened ones.

The company said its promotions drove customer traffic during the month but that they would hurt front-end margins in the quarter.

Pharmacy sales accounted for 65.3 percent of total sales for the month. Same-store pharmacy sales fell 0.5 percent, in part due to generic drug introductions and a shift in the calendar, the company said.