Bank of America's home page displayed an error message and its consumer online banking service was slow for a fifth day Tuesday.
Spokeswoman Tara Burke said the problems, which began Friday, are not the result of hacking. She said the bank was continuing to "assess the situation."
Bank of America , based in Charlotte, N.C., is the largest U.S. bank by deposits and has 29 million online customers.
A message at bankofamerica.com apologized for the slowdown and noted that customers can get into their accounts at an ATM or one of nearly 6,000 branches. The message suggested customers return online at a "non-peak time."
Burke did not say when the site would be fully restored, and she said the bank doesn't "break out the root cause" for problems its website encounters. She had said Friday and in following days that the problems had been resolved.
The site also experienced problems in January and March.
The latest problems follow the company'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.