so-called subprime mortgages were typically group of answer choices not held by the originating bank, but instead were resold for packaging into mortgage-backed securities. aggregated and then sliced into tranches each representing a different risk class: aaa, aa-bb, or unrated. not held by the originating bank, but instead were resold for packaging into mortgage-backed securities. additionally, they were aggregated and then sliced into tranches each representing a different risk class: aaa, aa-bb, or unrated.