EU competition regulators fined six financial institutions including Deutsche Bank, Royal Bank of Scotland and Citigroup a record €1.71 billion for rigging financial benchmarks.
The penalty is the biggest yet to be handed down to banks for rigging the benchmarks used to determine the cost of lending, one of the most brazen violations of conduct since the financial crisis.
It is also the highest competition penalty ever imposed by the Commission, the EU's competition regulator.
The other banks penalised are Société Générale, JPMorgan and brokerage RP Martin. Deutsche Bank received the biggest fine of €725m.
The European Commission said it would continue to investigate Credit Agricole, HSBC, JPMorgan and brokerage ICAP for similar offences.
The benchmarks involved are the London interbank offered rate, or Libor, the Tokyo interbank offered rate and the euro area equivalents. They are used to price hundreds of trillions of dollars in assets ranging from mortgages to derivatives.
"What is shocking about the Libor and Euribor scandals is not only the manipulation of benchmarks, which is being tackled by financial regulators worldwide, but also the collusion between banks who are supposed to be competing with each other," EU Competition Commissioner Joaquin Almunia said in a statement.
Deutsche Bank said it has set aside enough money to cover most of the €725m fine. JPMorgan confirmed its €79.9m penalty in the Libor case but said it would defend itself in the Euribor case. Société Générale declined to comment.
Unlike the six banks which admitted liability in return for a 10% reduction in their fines, Credit Agricole has refused to settle and will likely face sanctions next year. HSBC has also contested the EU's proposed penalty.
Both banks are expected to be formally charged today.
A spokesman for HSBC said the bank would defend itself vigorously in the Euribor case, while Barclays confirmed its co-operation with the Commission which helped it stave off a €690m sanction.
Authorities around the world have so far handed down a total of $3.7 billion in fines to UBS, RBS, Barclays, Rabobank and ICAP for manipulating rates, while seven individuals face criminal charges.
UBS paid a record fine of $1.5 billion late last year to the US Department of Justice and the UK's Financial Services Authority for rate-rigging.
EU fines can reach up to 10% of a company's global turnover.
UBS blew the whistle on the Libor and Tibor cases and will not be fined as a result. Barclays will escape a fine in the Euribor case because it alerted the Commission to the offence.