EU competition policy chief Margrethe Vestager has ruled that HSBC, French bank Credit Agricole, and US giant JPMorgan were part of a cartel of seven banks that worked together to manipulate the Euribor interest rate between September 2005 and May 2008.
HSBC has been hit with a €33.6mln penalty, Credit Agricole has been fined €114.7mln, and JPMorgan was ordered to pay a hefty €337.2mln.
Brussels said that traders at the banks used chat rooms and instant messaging services to try to “distort the normal course of pricing components for euro interest rate derivatives”.
The fines mark the culmination of a five-year investigation into Euribor rigging by the European competition regulator and come three years after the four other banks that were part of the cartel - Barclays, Deutsche Bank, Royal Bank of Scotland and Societe Generale - admitted guilt and agreed a settlement of almost €825mln.
HSBC, Credit Agricole and JPMorgan all held out, however, and continue to deny any wrongdoing.
Credit Agricole immediately said it would appeal its penalty and the other two lenders indicated they may do the same.
HSBC said it was “reviewing” the Brussels announcement and “considering our legal options”.
The move is the latest in a series of fines handed down to banks by regulators around the world for a host of misconduct issues and scandals, including the rigging of Libor.
Vestager said: “Banks have to respect EU competition rules just like any other company operating in the single market."