IntercontinentalExchange Inc. (ICE) said August average daily volume jumped 34% from a year earlier, as rival CME Group Inc. (CME) reported a 7% decline, continuing recent trends for both companies.

ICE has been continuing to pick up market share in recent months as trading slows at CME, its larger rival.

ICE said Wednesday an average of 1 million contracts were traded each day in August. Trading in ICE's Russell 200 mini futures, an option that continues to flourish, again led the growth, with volume up 17-fold. The Atlanta-based firm is energy focused but is attempting to attract business to its first-in-the-U.S. clearing house for over-the-counter credit derivatives.

CME - which has reported year-to-year declines since last fall - reported daily volume of 10.2 million, up 5% from July. The 7% decline from last year was the smallest drop of 2009.

August's fall was led by a drop in metals trading. Volume in its equity index also fell 10%, while electronic volume fell 6%. Interest-rate volume slumped 6% in August.

ICE and CME shares were closed Tuesday at $91.36 and $279.17 respectively and weren't active premarket. ICE is up 11% year to date, while CME is up 34%.

-By Joan E. Solsman, Dow Jones Newswires; 212-416-2291; joan.solsman@dowjones.com