The key banking systems were offline for more than three hours Fed says that the massive outage was caused by an ‘operational error’ Systems affected form the backbone of US banking and financial sector Fedwire is used by banks to transfer an average of $3.3 trillion every day FedACH handles smaller transactions such as paychecks and tax refunds The Federal Reserve payment systems used to settle transactions between U.S. financial institutions suffered a massive disruption due to an ‘operational error’. The system used by U.S. banks to execute some $3 trillion in transactions daily began suffering outages at around 11.15am Eastern time on Wednesday, and remained down for more than three hours.