JPMorgan Chase's (JPM) website shut down for some time on Friday, preventing bank customers from retrieving their accounts.
The New York bank took to Twitter to tell customers its online banking was "experiencing intermittent issues" that the company was working to resolve.
The outage endured for a few hours, bank spokesman Tom Kelly told American Banker. "We're back to normal response times now," Kelly said.
JPMorgan Chase is researching the cause of the outage, Kelly said.
Some customers complained the interruption prevented them from paying bills, according to comments posted on Sitedown.co, which tracks website outages. On Friday afternoon, the site had logged roughly 317 reports of people being unable to log in to their accounts at JPMorgan Chase within the preceding 24 hours compared with 340 reports in the past seven days.
The service glitch at JPMorgan Chase follows an outage at Bank of America (BAC), where online and mobile banking halted on Feb. 1 for roughly 10 hours following what a source close to the situation said was an internal systems issue.
The slowdowns at both JPMorgan Chase and B of A come after a series of cyber attacks that began in September and disrupted online banking at some of the nation's biggest banks.
A group of hacktivists who call themselves the Alqassam Cyberfighters claimed responsibility for the assaults, which the group said it mounted in retaliation for the posting on YouTube of a movie trailer the group charges is offensive to Muslims. Though the group said in January it would halt its campaign after someone took down one of the videos, it warned in an email Tuesday it would resume attacks if other copies of the video that remain on YouTube are not removed quickly.