Still, mortgages were acknowledged to be the most mathematically complex securities in the marketplace.

But three years ago, overly complex securities were one of the root causes of the crisis.

About $8 billion is in complex securities known as derivatives, the values of which are based on the performance of underlying assets.

The former issued 250 million dollars worth of complex securities (equivalent to about 3.75 billion in today's money) in 1929.

The lure of a complex security called a "residual interest bond" is a promise of higher yields.

Along with complex securities, foreign securities could be a target of fear.

In the mid 1980's, those complex securities were designed to help large corporations offset financial risk.

Bratton will continue to work with public entities and private organizations facing complex security or investigatory challenges.

The complex security for such a dangerous event has been in the planning for many years.

The prices of these complex securities have fallen sharply as interest rates have risen over the last two months.