CME Group Inc. CME -1.34% Friday pledged $300 million to help hasten the release of customer cash and other collateral trapped in the bankruptcy of MF Global Holdings Ltd. MFGLQ -12.03% . The money, put forth in the form of a financial guarantee to the trustee overseeing MF Global’s liquidation, was aimed to give the trustee “greater latitude” in dispersing funds to the individual...