CBOT Holdings, the parent of the Chicago Board of Trade, is suing its offspring, the Chicago Board Options Exchange, over membership rights. The case that may delay CBOE's demutualisation.

In the latest twist in the Chicago saga, CBOT Holdings today filed a lawsuit against the CBOE, seeking a court injunction "to enforce the rights of the CBOT's full members to participate in the CBOE's restructuring." The suit, filed in the Court of Chancery, also names the CBOE board, which includes CBOE chairman and chief executive William Brodsky, as defendants.