He decided the best way to do so was by shorting the debt backed by newly issued mortgages.

However, the electricity commission says that its debt, backed by the Mexican government, represents 130 percent of its sales.

The company's deferral of bond payments does not apply to debt backed by its Airbus planes, which make up 95 percent of its fleet.

Most bankers, despite the write-offs they would face, seemed enthusiastic about replacing troublesome Mexican loans with debt backed by Treasury securities.

The relationship went beyond traditional loans to a variety of complicated financings, including futures contracts involving offshore companies and debt backed by Enron's receivables.

One motivating factor is a looming $375 million payment on debt backed by aircraft, which the airline missed this week.

And the rush could have been exacerbated by the need to unwind debts backed by falling stock values.

A deal could be financed by debt backed by the steady income from ticket and merchandise sales.

The rejection comes as United is facing a critical Monday deadline for making a $375 million payment on debt backed by aircraft.

Investors in airport bonds are holding debt backed by commercial airlines that are using the proceeds to build hangars, baggage-handling facilities and other capital projects.