Not "could", "are".
It's actually much worse than that, if you can believe it. Because the derivatives have been packaged in extremely complex tranches it is impossible to unravel the liabilities. No one actually knows who is "supposed to" pay.
Yet, the expected revenues from them have been borrowed against and heavily leveraged to buy other assets.
Because the tranches are so huge (~$700 trillion) and complex there is no possibility of unravelling them, simply because we don't have the staff or the time to do it.
So in practical terms the tranches are worthless. This is why there has been so much effort put into propping up what is essentaily a dead system. How do you write off assets that are nominally worth 10 times the global gdp?
$this->bbcode_second_pass_quote('gnm', 'S')o potentially trillions in financial assets could decline 90%?
Well no sweat then.... And here we were all worried...
-G