Financial weapons of mass destruction.

(CBS) The world's financial system teetered on the edge again last week, and anyone with more than a passing interest in their shrinking 401(k) knows it's because of a global credit crisis. It began with the collapse of the U.S. housing market and has been magnified worldwide by what Warren Buffet once called "financial weapons of mass destruction."

They are called credit derivatives or credit default swaps, and 60 Minutes did a story on the multi-trillion dollar market three weeks ago. But there's a lot more to tell. As Steve Kroft reports, essentially they are side bets on the performance of the U.S. mortgage markets and the solvency on some of the biggest financial institutions in the world. It's a form of legalized gambling that allows you to wager on financial outcomes without ever having to actually buy the stocks and bonds and mortgages.

It would have been illegal during most of the 20th century, but eight years ago Congress gave Wall Street an exemption and it has turned out to be a very bad idea.

While Congress and the rest of the country scratched their heads trying to figure out how we got into this mess, 60 Minutes decided to go to Frank Partnoy, a law professor at the University of San Diego, who has written a couple of books on the subject. Ask to explain what a derivative is, Partnoy says, "A derivative is a financial instrument whose value is based on something else. It's basically a side bet."

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