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Finance is the art of passing money from hand to hand until it finally disappears.
Robert W. Sarnoff
Looks these started in 1968 [ Government National Mortgage Association ] for government bundled, and backed by the full faith and credit of the US taxpayers....
It appears the need by the Resolution Trust Corporation to rapidly resolve the S&L mess in the late 1980s and early 1990s spawned the commercial MBS.
some background
From scanning some other sites it appears that there are huge numbers of subtle, nuanced and arcane types of MBS, a few with actual real property as collateral (which may now be grossly overvalued, but is still *SOMETHING* concrete as backing) and many more with "mark to myth" derivatives for backing (largely underwritten by "The Left Bank of the Mississippi" and other established financial powerhouses).
Unka' George [George McDuffee]
------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?
Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).