If you're going to make a point of it then don't leave out the part about how it happened.
What they were doing was, they'd take a block of subprime mortgages and split them up into tiers. Basically they'd agree to wait to see who defaulted and then the top tiers would get all the mortgages people actually paid back and the bottom tiers got the ones they didn't. If 10% of the mortgages defaulted then anyone who bought at the 10th percentile tier gets all the defaults and everybody else gets paid. If 20% of them defaulted then the ones who bought the 20th percentile tier lose too, but the 30th percentile tier still gets paid.
The highest tiers were rated AAA, because for them to lose you'd have to have preposterously high default rates.
Then we started seeing preposterously high default rates.