Bank of America's mobile and online banking services crashed on Friday after being hit by 'technical issues', with customers unable to access accounts.
The US bank confirmed in a series of tweets that its consumer banking services had crashed, before being brought online again on Saturday.
"We're experiencing some technical issues and we are working to resolve as soon as possible," one tweet read.
The bank subsequently issued an apology to customers after online and mobile banking accounts came back online, and claimed that log-in, passwords and account information were "never at risk".
Bank of America customers also took to Twitter to vent their frustration over the crash. The bank has over 29 million customers using its online banking service.
Although the bank has not issued a statement on the reason for the system crash, sources cited by the Washington Post note that it was likely due to an 'internal glitch'.
In 2011 Bank of America customers were unable to access online accounts following a botched systems update, denying that it had been the victim of a hacktivist attack.
In the past the bank has been targeted by hactivist groups using DDOS attacks, such as Islamist group Izz ad-Din al-Qassam Cyber Fighters.
The Bank of America outage is the latest systems failure to affect major financial sector organisations this year.
Last month Lloyds Bank customers were subject to account payment delays after routine updates to its account information systems caused its Faster Payments service to crash.
The BATS Global Market revealed last month it had allowed hundreds of bad trades to occur due to errors on its exchange which went unnoticed for four years, affecting around 250 customers.