Americans owed some $10 trillion on their mortgages, most of which were sound with payments made on time. However financiers bundled the mortgages into very complicated packages called "'''collateralized debt obligations''''<ref> That is, homeowners were obligated to pay the debts and the collateral behind them was the physical house.</ref> or CDOs. Hundreds of billions of dollars worth of CDO's were sold to banks, pension funds and financiers in the U.S. and Europe. Generally they borrowed cash to buy the CDOs. The risk was that if the CDO's declined in value, they would not be able to repay those loans. The CDOs were especially attractive because they were not regulated by the government; experts are not sure how many trillions of dollars are involved. | Americans owed some $10 trillion on their mortgages, most of which were sound with payments made on time. However financiers bundled the mortgages into very complicated packages called "'''collateralized debt obligations''''<ref> That is, homeowners were obligated to pay the debts and the collateral behind them was the physical house.</ref> or CDOs. Hundreds of billions of dollars worth of CDO's were sold to banks, pension funds and financiers in the U.S. and Europe. Generally they borrowed cash to buy the CDOs. The risk was that if the CDO's declined in value, they would not be able to repay those loans. The CDOs were especially attractive because they were not regulated by the government; experts are not sure how many trillions of dollars are involved. |