MF Global sues banks for restricting competition in CDSNEW YORK, July 30 | Tue Jul 30, 2013 10:21pm BST NEW YORK, July 30 (Reuters) – MF Global has sued 12 large banks, accusing them of restricting competition in the $25 trillion credit default swap market, the latest in a string of lawsuits alleging that banks impeded new entrants by blocking exchange trading of the contracts.