The Chicago Board of Trade confirmed it has begun talks with the Chicago Mercantile Exchange (CME) recently that go beyond earlier plans to link the nation's two largest exchanges, which could include a merger. The exchanges already have a plan to merge their back-office operations, and board members have consistently backed the idea of combining the exchanges as a way to cut costs and remain competitive with computer networks and over-the-counter markets. 'The Chicago Board of Trade and the CME have had discussions over the past 10 days that go beyond' combining back-office operations, a spokesman said. 'There are no plans for an announcement' about any agreements. The two exchanges are negotiating a merger, CNBC and the Wall Street Journal reported.