The exchange's Web site is back online, but only with a statement that it's closing all transactions for the time being.
The agency reportedly has a special division that monitors international banking and credit card transactions, says Germany's Der Spiegel.
In partnership with retailers, banks, and credit card companies, Apple will launch the iOS mobile payment service Apple Pay in the US in October.
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Company marketed specialized computers designed to produce the cryptocurrency but delivered useless machines, according to an FTC complaint.
The online-payments company is testing the waters by partnering with other companies willing to process transactions using the digital currency.
Coin Center, a newly created research and advocacy center, will focus on public policy issues faced by the virtual currency.
Apple has already confirmed that it won't charge merchants or consumers for card transactions, yet it's unclear how much in fees the company can generate from banks.
Apple Pay could realistically be a huge business, but adoption will depend on sales of iPhone 6 and 6 Plus, consumer willingness to change and retailer IT infrastructure.
Doors open at Apple stores across the globe as the new iPhone 6 and 6 Plus hit the shelves.
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