Bank of America Corp. scrambled to restore service Friday to its enormous customer base -- 40 million households -- which spent most of the day without access to online, mobile and telephone banking services.
A prominent consultant called the outage "inexcusable."
In tweets Friday, the bank said the outage stemmed from technical issues.
That raised the question how such a massive outage could occur at BofA, the second-largest U.S. bank. The outage follows efforts by Chief Executive Brian Moynihan to overhaul bank operations to better cater to costumers' needs.
BofA has invested $500 million in mobile and online banking since 2008, a period in which branch transactions have dropped 35%. Moynihan says Internet banking is more convenient for customers as well as cheaper to operate.
Bank of America was closing in on 12 million mobile customers at the end of 2012, Moynihan boasted at a financial services conference in December. "We average about 8,000 to 10,000 users a day," he said. "By the time I get done talking, 300 more people will have signed up."
Given that strategy, not having backup systems in place for electronic banking and call centers "is absolutely inexcusable," said economist bank consultant G. Michael Moebs in Lake Bluff, Ill.