Trading volume at CME Group Inc. (CME) picked up in August compared to the previous month due mainly to increased activity in its core interest rate complex.

Total volume at the world's largest futures exchange was down from year-ago levels, but far surpassed August volume totals at CME's European rival, Eurex.

CME reported Wednesday that an average of 10.2 million contracts changed hands each day last month, up 5% from July and 7% below August 2008. It was still CME's best year-over-year showing in 2009, as the Chicago-based exchange battles to recover from massive deleveraging during the global credit crunch.

For the month, 214 million contracts were traded in August compared to 191.5 million at Eurex.

The unit of Deutsche Boerse AG (DB1.XE) reported average daily volume of 9.1 million contracts, down from 9.5 million in July and the same amount in August 2008.

CME shares were 0.2% higher Wednesday at $279.62. Deutsche Boerse shares closed 1.2% higher at EUR53.38.

Stock index derivatives volume outpaced interest rate activity at Eurex last month.

The same was not the case at CME, as an average 4.7 million interest rate contracts were traded each day in August versus 2.5 million per day in its stock index product line.

August interest rate volume at CME was 14% higher than July, but down 6% from the same period last year.

In equities, August volume was about steady compared to July, and 10% lower compared to the same time last year.

CME's interest rate products benefited during August from the quarterly roll period that enables the exchange to collect additional trading fees.

Traders executing the roll in Treasury futures close their positions in the expiring September contract and re-open them in the new lead month, which is December.

CME said its average daily Treasury volume of almost 2.3 million contracts was down 16% from August 2008.

Since July 10, CME has faced competition in the Treasury complex from the consortium-supported exchange, ELX. The fledgling operation said Wednesday that it attracted about a 1.9% market share in August.

Overall rate-per-contract at CME - a measure of profitability - was at $0.821 for the three-month period ending in July, compared to an upwardly revised $0.823 for the three months ending in June. Last month, CME said the rate-per-contract through June was $0.816.

A CME spokesman said the revision was due to "harmonization" of tracking volumes for CME legacy products and energy and metals at its New York Mercantile Exchange unit.

CME reported Nymex energy volume in August was at an average 1.5 million per day, up 5% from the same time last year.

CME's smaller Atlanta-based competitor, IntercontinentalExchange Inc. (ICE) - primarily an energy market operator - reported a 34% year-over-year increase in trading activity. Average daily volume in August was a little over 1 million contracts, or a total of 21.2 million.

ICE also said the exchange established record open interest of about 2.8 million contracts in August. Open interest represents the number of contracts bought or sold, but left open without offsetting transactions.

Equity index trading at ICE continued to grow, with its mini-sized Russell 2000 futures and options up about 17 fold compared to August 2008.

ICE derivatives trading on sugar was up almost 79% compared to August 2008, with average daily volume at almost 190,000 contracts.

The all-electronic exchange is continuing to take advantage of its head start in clearing over-the-counter credit default swaps. Through August, ICE said its clearing houses have cleared $2.2 trillion in CDS transactions.

ICE shares were near unchanged Wednesday at $91.34.

-By Howard Packowitz, Dow Jones Newswires; 312-750-4132; howard.packowitz@dowjones.com

(Joan E. Solsman and Jacob Bunge contributed to this report.)