All other CBOE classes, including SPX and VIX, opened as scheduled at 8:30 a.m. and were unaffected by this isolated issue. The impacted classes were open for trading at 8:40 a.m., with complex order trading in all of the classes in the affected cluster available by 9:04 a.m.

This issue was triggered by a product maintenance function being performed for a symbol change to one of the classes in the cluster. The software maintenance function was recently updated in preparation for the extended trading hours initiative.

As part of our broader, ongoing review, we are in the process of retaining an independent systems consultant to thoroughly evaluate the rollout procedures associated with our extended trading hours initiative. We are committed to extended trading hours, and this review will result in a comprehensive evaluation of our rollout procedures and provide guidance going forward.