While the Chicago Board of Trade and the Chicago Mercantile Exchange are trying to consummate their merger and shoo away competing bids, they’re grappling with a European rival nipping at their heels in federal court.

The European exchange, Eurex A.G., sued the Chicago institutions through its U.S. affiliates in October 2003 on antitrust claims and is now demanding documents in discovery that the Chicago exchanges have filed with the U.S. Justice Department as part of their proposed merger. US Futures Exchange v. Board of Trade of the City of Chicago, No. 04-6756 (N.D. Ill.).