CME Group, the world's largest and most diverse derivatives exchange, announced that May volume averaged 10.7 million contracts per day, down 15 percent from May 2008, but up 17 percent from April 2009. Total volume was 214 million contracts for May, of which 79 percent was traded electronically. Electronic volume averaged 8.4 million contracts per day, down 14 percent from the prior May and up 15 percent sequentially.