On September 17th, CME Group responded to the CFTC's letter regarding a Chicago Board of Trade self-certified Market Regulation Advisory Notice issued on October 19, 2009. In that notice, CBOT stated that its rules do not permit the execution of exchange of futures for futures transactions. The notice was issued shortly after the CFTC approved an ELX Futures rule authorizing participants on ELX to carry out EFF transactions. CFTC Release No. PR-5872-10. Reuters quotes CME as contending that "Requiring CBOT to accept EFFs effectively allows ELX traders to leverage the liquidity developed by CBOT without providing acceptable compensation to CBOT, while also harming CBOT markets and subverting a critical element of competition among exchanges." Defense.