BRUSSELS (Reuters) -The European Commission on Thursday said it had opened an antitrust investigation against stock exchange companies Deutsche Boerse and Nasdaq.

The Commission said it suspected the companies of breaking EU competition rules in the sector for listing, trading and clearing of financial derivatives.

"Deutsche Boerse and Nasdaq entities may have entered into agreements or concerted practices not to compete in the European Economic Area," it said. "In addition, the entities may have allocated demand, coordinated prices and exchanged commercially sensitive information."

(Reporting by Bart Meijer, editing by Inti Landauro)