Customers of Fifth Third Bank may have noticed some trouble with the company's website on Tuesday, January 8th.
The bank says it was the victim of a cyber attack.
This particular type of attack is known as a "denial of service", which creates a connectivity issues for users.
Customers flooded social media yesterday saying they could not access the bank's site with mobile apps.
The bank responded via twitter, "we’re assessing delays on 53.com, which may have impacted mobile access." A later tweet added, "Accounts have not been impacted and are secure. More information to come."
Cincinnati news outlets (where the bank is based), later reported that Fifth Third had suffered a second "denial of service" cyber attack since last Thursday.
The Wall Street Journal has reported on waves of denial of service cyber attacks hitting U.S. Banks since Fall 2012.
The bank is telling its customers the system was not hacked, and their accounts and personal information was not compromised.