One of America’s biggest banks accidentally transferred more than $80 trillion (£64 trillion) to a customer’s account after a “fat finger” input error by an employee. Citigroup, one of America’s “big four” lenders, erroneously transferred $81 trillion to the account in April last year instead of the $280 requested because of a keyboard mistake by a bank staffer. The huge sum, worth more than 20 times Britain’s entire gross domestic product (GDP), was approved after being checked by two of the bank’s employees, before being sent to the customer account the following morning. The payment was only flagged after a...