Exchange operator CME Group Inc. Friday lost an effort to strike down a rule at the rival Chicago Board Options Exchange Inc. that keeps some members at a CME unit from exercising their right to trade at the options market. Delaware Court of Chancery Vice Chancellor John Noble refused to issue a temporary restraining order against the new rule, which the options exchange enacted in the wake of the July merger that created CME Group. That deal brought together CME, owner of the Chicago Mercantile Exchange, and CBOT Holdings Inc., owner of the Chicago Board of Trade.

Board of Trade members have long held special options-exchange rights, but the options exchange says the CME-CBOT merger wiped out those special rights.

The judge said Friday that Board of Trade members have a good case that the options exchange's new rule barring them from the trading floor does unfair damage to their economic interests. But he refused to issue the restraining order, saying money will be an adequate remedy if the rule is ultimately struck down after trial.

The Delaware judge also stayed action in a lawsuit filed by the Board of Trade against the options exchange last year, in which Board of Trade members claimed they are being cut out of a fair share of the option exchange's demutualization.

Board of Trade members argue that the contribution they made in creating the CBOE in 1973 entitles them to a share of the equity being distributed in the options exchange's demutualization. The options exchange has asked the Securities and Exchange Commission to endorse its view that Board of Trade members aren't entitled to anything in that process.

Judge Noble said he wants to see what the SEC says about the dispute before court action moves forward.