Target Corp. (TGT) expanded its $4 generic drug program to all of its U.S. pharmacies on Monday, moving beyond states where it was matching a plan offered by rival Wal-Mart (WMT).

Target said all of its 1,287 pharmacies across the United States would now offer some generic drugs for $4. It was not immediately clear which generic drugs were on Target's list. Previously, the discount retailer had matched the list of drugs being sold for $4 at Wal-Mart.

Wal-Mart Stores Inc., the world's largest retailer, started selling certain generic drugs for $4 per prescription in Florida in September. Since then, Wal-Mart has brought the $4 drugs to 37 more states and said it plans to extend the plan to additional states as fast as it can.

Wal-Mart has also added more drugs to its list, such as pravastatin, a generic form of Bristol-Myers Squibb's (BMY) cholesterol drug Pravachol.

The cut-price drugs are now available in 3,009 Wal-Mart pharmacies. Wal-Mart has about 3,960 U.S. stores.

When Wal-Mart announced the $4 plan in September, it drove down shares of generic-drug makers, pharmacy-benefit managers and drugstore chains such as Walgreen Co. (WAG) and CVS Corp. (CVS).

The drugstore companies and analysts have said they see little threat from Wal-Mart's plan, noting that cash prescriptions account for only a small portion of their profits.

Shares of Minneapolis-based Target, which operates 1,494 stores in 47 U.S. states, slipped 28 cents to $57.94 on the New York Stock Exchange, while shares of Wal-Mart rose 37 cents to $47.87.