The nation's fourth-biggest bank by assets said some customers had trouble retrieving their accounts online.
Wells Fargo spokeswoman Sara Hawkins said in an email the bank is "seeing an unusually high volume of traffic, which is creating slow or intermittent access to our website for some online customers."
The "vast majority" of customers are not impacted, she added.
"We are aware that some folks are having access issues w/ the site," the company tweeted on Tuesday evening.
Some people took to the bank's Facebook page Wednesday morning to say they were unable to get online.
As of Wednesday morning, Sitedown.co, which records website outages, had logged 494 reports of people claiming to be unable to log in to their accounts at Wells Fargo within the preceding 24 hours compared with 509 reports in the past seven days.
Wells Fargo's website "was made completely out of reach," read a message posted Tuesday on Hilf-Ol-Fozoul, a website that has tracked activity by the Izz ad-Din al-Qassam Cyber Fighters Group, which threatened on Dec. 10 to sustain so-called denial of service attacks against JPMorgan Chase (JPM), Bank of America (BAC), U.S. Bank (USB), PNC (PNC) and SunTrust (STI).
Wells Fargo was not among banks cited by the group, which pointed to slowdowns that hit websites at U.S. Bank and PNC on Thursday as evidence of its ability to strike anew.
