"financial weapons of mass destruction.": With 10,000 disparate mortgages underlying the paper, cash payments and risk impossible to predict

Wall Street Bank Run | By David Ignatius \ Thursday, February 21, 2008; Page A15

It doesn't look like an old-fashioned bank run because it involves the biggest financial institutions trading paper assets so complicated that even top executives don't fully understand the transactions. But that's what it is -- a spreading fear among financial institutions that their brethren can't be trusted to honor their obligations.
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... The problem, he said, is that financial institutions are required to "mark to market" their tradable assets (which is a fancy term for setting a value) even when there isn't a functioning market. In many cases dealers can do little more than guess at the value -- and other investors down the line know it.

To explain how this happened, the CFO took a simple example of residential mortgages. As financial engineering improved in the 1990s, these individual loans were gathered into bundles -- 10,000 home loans of $100,000 each, let's say -- and turned into a $1 billion security that could be traded in ways the individual mortgages never could. But that wasn't enough. The financiers realized they could boost their profits by carving the $1 billion package into different slices, with different risk levels. In that way, a pool of B-rated mortgage assets could generate a slice that was rated AAA, because it was judged the slice most likely to be repaid.

But what happened when the real estate market confounded recent history and began to turn down? People holding the paper could no longer be sure if or when their particular slice would be repaid. The traditional accounting approach -- of estimating the projected cash flow and then discounting for the risk -- didn't work. With 10,000 disparate mortgages underlying the paper, both the rate of cash payments and the risk of default were impossible to predict. So the pyramid began to wobble.

The hubris in this system was Wall Street's confidence that it could value paper securities that had been sliced and diced so many times that they no longer had solid connections to their underlying assets. The nation's leading financier, Warren Buffett, had warned years before that "derivatives," whose value was balanced loosely on the real assets underneath, were the equivalent of "financial weapons of mass destruction." But in the rush for profits, nobody listened.

I've saved the worst for last. Do you want to know who is bailing out America's biggest banks and financial institutions from the consequences of their folly -- by acting as the lender of last resort and controller of the system? Why, it's the sovereign wealth funds, owned by such nations as China and the Persian Gulf oil producers. The new titans are coming to the rescue, if that's the right word for their mortgage on America's future.