Bank of America's consumer online banking service was slow for a fifth day Tuesday, and the bank still wasn't saying what the problem was.
The bank said many times starting Friday that it had resolved the problem, but visitors to its home page still saw an error message for much of Tuesday saying the site was "running slowly" and customers might experience delays or have difficulty accessing parts of it.
The message encouraged customers to try again at "a non-peak time" or visit an ATM or one of nearly 6,000 branches to get into their accounts.
Bank of America Corp., based in Charlotte, N.C., is the largest U.S. bank by deposits and has 29 million online customers.
Spokeswoman Tara Burke said the website problems were not the result of hacking. She declined to "break out the root cause" for the problems but said the bank was continuing to assess the situation. She said Tuesday evening that the site was largely operating normally.
This wasn't the first time this year that Bank of America's website experienced problems. Customers also had difficulty accessing their accounts in January and March. In both instances, the bank said the problems resulted from routine system upgrades.
The most recent stumble is significant because of its duration, said Ben Rushlo, director of performance management at Keynote Systems Inc., which monitors the performance of company websites.
He said it was the longest major banking website problem he's seen in 13 years with Keynote.
"It's extremely unusual in 2011, given the prevalence of online banking and that it's the de facto way people interact with banks," Rushlo said. "This is something gone awry. There's no way they would've intentionally taken down their home page."
Rushlo said that the incident doesn't seem connected with Bank of America's announcement Thursday that it would start charging customers $5 a month to use their debit cards.
Several major banks have introduced new or higher fees for checking account customers in the past year. The industry says the changes are needed because of a new regulation that limits the fees they can collect from merchants whenever customers swipe their debit cards.