In a report last month, Bain & Company predicted that by partnering with a bank and employing the same low-margin strategy it used to gain market share in e-commerce, Amazon could build financial relationships with 70 million customers -- as many as Wells Fargo & Co. -- in just five years.

“Large technology firms already have established brands and access to customers, both of which provide a massive distribution advantage,” Bain partners Gerard du Toit and Aaron Cheris said in the report.