CRAIG DONOHUE, CHIEF executive of CME Group, is surprisingly calm as he speaks to Euromoney in his office on South Wacker Drive in Chicago. That day press reports emerge of Nasdaq preparing for a counter-bid for NYSE Euronext, with rumours circulating of a tie-up with the Intercontinental Exchange (ICE) to do so. Exchange merger frenzy is in full flow. Since the start of the year Deutsche Börse and NYSE Euronext have announced talks to join up to form the world's largest exchange.