The U.S. food retailing industry has undergone unprecedented consolidation and structural change in recent years. Large retailers have since 1996 purchased almost 3,500 supermarkets, representing annual grocery store sales of more than $67 billion. The nationwide share of sales for the four largest retailers rose from nearly 16 percent in 1992 to almost 29 percent in 1998. Consolidation is likely to continue, and raises questions about the implications for consumers and food market suppliers.