The European Union has issued a $2.3 billion fine against six major financial firms over the rigging of global interest rates. The banks and brokers were found to have colluded to alter the benchmark for rates on trillions of dollars in transactions across the globe, meaning millions of borrowers paid the wrong amount on their loans. The rigging covered the Euro Interbank Offered Rate, or Euribor, and London Interbank Offered Rate, or Libor. All six banks are from Europe or the U.S., including JPMorgan and Citibank. The banks UBS and Barclays were hit with around $2 billion in fines last year.