(ANSA-AFP) - BRUSSELS, NOV 6 - The EU on Thursday announced a formal antitrust probe against stock exchange operators Nasdaq and Deutsche Boerse over "possible collusion" involving financial derivatives. The European Commission said it suspected US-headquartered Nasdaq and Germany's Deutsche Boerse "may have entered into agreements or concerted practices not to compete" in the EU when dealing with certain derivatives. (ANSA-AFP).