(Chicago Tribune) Shares of Wal-Mart Stores Inc .fell 3 percent on Friday after Bloomberg quoted a mid-level executive’s email as saying the world’s largest retailer had the worst sales start to any month in seven years in February.

Wal-Mart executives blamed the poor performance on increased payroll taxes as well as delayed tax returns, Bloomberg said.

Higher payroll taxes are seen as a potential problem for Wal-Mart and other discount retailers who target lower-income customers.

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