Walgreen Overcharges, Reimburses Customers

Walgreen Co., the largest U.S. drugstore chain, accidentally overcharged as many as 4 million customers buying gifts and decorations the two days before Christmas because its payment-processing system malfunctioned from overuse.

Walgreen, which operates about 4,700 stores in 44 states, discovered the error on Christmas Day and electronically reimbursed customers whose credit or debit cards had been incorrectly double- and triple-charged, said company spokesman Michael Polzin. Some credits may not post on customers’ accounts until early next week, he said.

Shares of Walgreen fell 42 cents to $38.37 on the NYSE.