The European Commission has accused 13 banks, including Barclays, HSBC and the Royal Bank of Scotland, of colluding to hamper competition in the credit derivatives market.
The regulatory body said the banks infringed EU antitrust rules which prevent them from making anti-competitive agreements, after banks effectively stopped exchanges from entering the credit derivatives business between 2006 and 2009.
The commission found that Deutsche Börse and the Chicago Mercantile Exchange tried to enter the credit derivatives business between 2006 and 2009, but were refused a licence for exchange trading by ISDA and Markit.
A report from the Commission also reveals several investment banks sought to shut out exchanges in other ways, for example by coordinating the choice of their preferred clearing house.
Apart from the three UK banks, the statement also criticised the actions of Bank of America Merrill Lynch, Bear Stearns, BNP Paribas, Citigroup, Credit Suisse, Deutsche Bank, Goldman Sachs, JP Morgan, Morgan Stanley and UBS, as well as the International Swaps and Derivatives Association (ISDA) and data service provider Markit.
Overall the letter accuses the banks of acting collectively to shut out exchanges from the market on fears this would have reduced their revenues from acting as intermediaries in the over-the-counter market.
Commission Vice President in charge of competition policy Joaquín Almunia said: "It would be unacceptable if banks collectively blocked exchanges to protect their revenues from over-the-counter trading of credit derivatives.
"Over-the-counter trading is not only more expensive for investors than exchange trading, it is also prone to systemic risks."
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