CME Group, the world's leading and most diverse derivative marketplace, on Friday defended Citigroup Global Markets Inc. and that its activities in the CME Group's stock index futures markets does not appear to be unusual.

"While our policy is not to comment on individual participation in our markets, in light of volatile market conditions, CME Group confirmed that activity by Citigroup Global Markets Inc. in CME Group stock index futures markets does not appear to be irregular or unusual in light of market activity today," CME said in a statement.

CME made the statement amidst speculations that Citigroup may have been involved in illegal trades in its activities at CME Group.

As the world's leading and most diverse derivatives marketplace, CME Group is where the world comes to manage risk. CME Group exchanges offer the widest range of global benchmark products across all major asset classes, including futures and options based on interest rates, equity indexes, foreign exchange, energy, agricultural commodities, metals, weather and real estate.

CME Group brings buyers and sellers together through its CME Globex electronic trading platform and its trading facilities in New York and Chicago. CME Group also operates CME Clearing, one of the largest central counterparty clearing services in the world, which provides clearing and settlement services for exchange-traded contracts, as well as for over-the-counter derivatives transactions through CME ClearPort. These products and services ensure that businesses everywhere can substantially mitigate counterparty credit risk in both listed and over-the-counter derivatives markets.