Freddie Mac this week announced a new class of single-family MBS backed by mortgages previously repurchased from MBS because they were in serious delinquency. Both government-sponsored enterprises began aggressively buying seriously delinquent loans out of their MBS trusts at the beginning of 2010 because new accounting rules required them to consolidate all their outstanding MBS on their balance sheets. Buying the distressed loans out of the MBS trusts had no impact on their financial accounting, but it allowed them to better manage...