New technology is upending everything in finance, from saving to trading to making payments.

Just five years ago, there were more Bank of America branches in the US than Walmart stores. But in an effort to cut costs, the bank has closed about a fifth of its branches since then—and is now warning of more closures to come.

“We took 1,400 branches out of the system, which is bigger than some entire companies out there,” CEO Brian Moynihan said on a July 15 call with analysts to discuss the company’s second-quarter earnings (they nearly doubled to $5.32 billion). “We expect there to be more pressure downward.” Bank of America currently has about 4,800 branches.

The bank’s rationale for closing branches goes beyond cutting costs: “Customer behavior is changing,” Moynihan said, noting that the number of mobile banking customers has more than doubled in the past four years to more than 17 million people. Now, 13% of Bank of America’s checks are deposited via mobile.

“We are moving because customers are moving in how they conduct business,” Moynihan said, cautioning that “if you do it too much, too quickly, you’ll upset the clients.”

Moynihan also mentioned that the bank is seeing about 10,000 customers a week book appointments online to come into the branch, up from 2,000 a week last year. This allows the bank to better anticipate the need for staffing, and adjust staffing levels accordingly.

Along with the move to mobile and the outright branch closures come 15 straight quarters of headcount reduction. Although the bank said it is hiring more financial advisers (plus 1,500 interns this summer), it has slashed more than 70,000 jobs since 2011 and is likely to cut even deeper.