Norm Betts | Bloomberg | Getty ImagesVisa shares dropped sharply in midday trading Friday after a report said the Justice Department has opened an investigation into its debit card business and possible anticompetitive practices.The department’s antitrust division has started to collect information on whether Visa, the largest card network in the United States, has curbed merchants’ capacity to route debit-card transactions over less-expensive networks, according unnamed sources who spoke to The Wall Street Journal.Those sources added that DOJ investigators’ questions are centered on online debit-card transactions, but have also included inquiries about in-store issues as well.Visa, which had seen …
