Securities market participants in the United States include corporations and governments issuing securities, persons and corporations buying and selling a security, the broker-dealers and exchanges which facilitate such trading, banks which safe keep assets, and regulators who monitor the markets' activities. Investors buy and sell through broker-dealers and have their assets retained by either their executing broker-dealer, a custodian bank or a prime broker. These transactions take place in the environment of equity and equity options exchanges, regulated by the U.S. Securities and Exchange Commission (SEC), or derivative exchanges, regulated by the Commodity Futures Trading Commission (CFTC). For transactions involving stocks and bonds, transfer agents assure that the ownership in each