Collateralized debt obligations (CDO) and other structured finance products trade over-the-counter rather than on an exchange, at least in the United States.
The development of the concept of public debt also allowed cities and nations to finance their commercial expansion and to develop trade, magnifying the need for competitive financial services.
Corzine used the repo trade to finance purchases of billions of dollars of volatile European sovereign debt instead, thereby multiplying the liquidity and risk management needed to come out ahead.