This lawsuit was filed to prevent ISE from listing and trading index options on the S&P 500 and Dow Jones Industrial Average in conflict with CBOE's exclusive license for options on those indexes.

This lawsuit was originally filed in Illinois state court, and ISE subsequently removed the case to Illinois federal court. The Illinois federal court agreed with CBOE and the index providers to return the case to Illinois state court on the basis that there is no federal jurisdiction to consider these state law claims (including misappropriation and unfair competition) and that these claims are not preempted by federal law. The Illinois Supreme Court has recognized that state law forbids the use of proprietary indexes in trading without a license from the index provider.

"We are gratified by today's decision, which confirms our belief that Illinois state court is the appropriate forum for the resolution of this dispute. Legal precedent in Illinois fully supports CBOE's position. CBOE has made considerable investments in creating, developing and marketing index options, and we will continue to work with Dow Jones and S&P - the owners of these indexes - to defend our exclusive rights to list and trade options on these indexes," said William J. Brodsky, CBOE Chairman and CEO.

CBOE, the largest options marketplace in the U.S. and the creator of listed options, is regulated by the Securities and Exchange Commission (SEC).