Standard & Poor’s credit rating service placed CME Group on “Credit Watch Negative” last week after the Chicago Mercantile Exchange announced that it has introduced a new class of clearing membership — Financial Instruments Clearing Membership — for exchange customers that conduct proprietary trading of listed interest rate products. The class would provide margin benefits of up to 65 percent, and help CME defend its business from a similar, recently-approved offering by rival NYSE Euronext, which is targeting interest rates.