U.S. regulators should put on hold CME Group Inc.'s plan toblock traders from engaging in transactions with themselves toensure it sufficiently restricts the illegal trades, said BartChilton, a member of the Commodity Futures Trading Commission(CFTC).

CME's plan to prevent wash trades, in which a party buys acontract from itself, should be put under review for additionaltime and not automatically take effect July 1, Chilton said inremarks prepared for a speech today at the Trading Show Chicago2013 conference. Chilton, one of three Democrats on the commission,said the agency should take additional steps to vet the CMEguidance and determine if other exchanges will have similar orbetter policies.

“Right now there are simply too many unanswered questions thatneed to be addressed from an oversight and surveillanceperspective, and potentially from an enforcement perspective,”Chilton said. “We need to take a deep breath and ensure that weknow, to the best of our ability, what might occur.”