From purchasing Whole Foods to introducing the ever popular “echo” and dominating online sales, the last few years have been huge for Amazon.com. Now, the retail giant is talking with JPMorgan Chase about building its own online-banking product—and that should have other major banks worried.

During the last two decades, Amazon has transformed from exclusively selling books online to offering products and services that are used by more than half of US households. Bain & Company analysts describe the transition to banking as a game changer and imagine that Amazon banking services could grow to more than 70 million US consumer relationships over the next five years. Bain’s assumption is that a little more than half of Amazon’s US customers will choose to also have a financial relationship with the company.

Known for exceptional customer service, it doesn’t come as a surprise that 45 percent of LendEDU survey respondents were open to using Amazon as their primary banking account, while 49.6 percent would use an Amazon savings account. Shopping with an Amazon checking or savings account would not only be convenient for customers, it would cut out credit-card companies entirely—thus saving Amazon and consumers substantially on interchange fees.

While banks have been spending billions trying to repair their reputations since the financial crisis of 2008, Amazon has continued to innovate and use customer profiles and data to its advantage. Karen Petrou, managing director of Federal Financial Analytics, told MarketWatch that banks are making a huge mistake when it comes to what they know about their customers.

“Banks are sitting on an enormous amount of consumer financial data, but they don’t know what to do with it,” Petrou said. “The platform companies are big data companies.”

Amazon is also going after a demographic that banks can’t seem to touch: teenagers and the “underbanked,” or those who would find it difficult to otherwise shop online. These markets were previously addressed with Amazon Cash cards that let anyone add cash to an Amazon account by purchasing a card at a local retailer. Parents with children aged 13-17 could also go around cash cards by assigning pre-set spending limits in their own Amazon accounts.

This potential partnership with JPMorgan Chase would be the second major agreement involving Amazon CEO Jeff Bezos in the past year. Bezos, Warren Buffet, and JPMorgan Chase recently announced a joint effort to reduce health-care costs for their employees that had other insurers stocks drop following the announcement.

Big-bank shareholders don’t seem too worried at the moment, but once more formal plans are announced, I don’t doubt that the “Amazon effect” will have banks scrambling to compete.