The Charlotte, N.C., bank would not say exactly how many of its 29 million online banking customers were unable to access their accounts during the outage. The problem appeared at around 7 a.m. Eastern time, and was resolved about 5:15 p.m., according to spokeswoman Tara Murphy Burke.
She said the majority of customers could access online banking during the day, but acknowledged that the system was very slow for those who could get in. As news spread of the outage spread during the day, traffic to the website increased and it became even more difficult to access.
Burke said the problem cropped up after a "routine systems change" overnight. The bank's ATM network operated normally throughout the day, she said.
It's not the first time customers of the nation's largest bank have had trouble accessing their accounts. The site was down for about four hours on Aug. 27, and there was another outage about a year ago.
Other banks have had similar problems, including a problem at Chase.com in September that persisted for more than a day.
In December, Bank of America joined several other financial institutions in refusing to handle payments for WikiLeaks, the secret-releasing organization that is rumored to be preparing a release on the bank itself. The bank's actions followed similar moves by MasterCard Inc. and PayPal Inc. The bank's site did not show any impact from hackers at that time in response to its refusal.
Bank of America shares added 48 cents, or 3.3 percent, in Friday's session to close the week at $15.25.