National Market System

The National Market System (NMS) is the national system for trading equities in the United States.

The System includes all the facilities and entities which are used by broker-dealers to fulfill trade orders for securities. This includes:

Major stock exchanges, such as NYSE and Nasdaq.
A national central securities depositary for book-entry transfers (Depository Trust Company pursuant to Article 8 of the Uniform Commercial Code of New York State).
A depositary nominee (Cede and Company) to retain custody of stockholder rights with respect to immobilized jumbo stock certificates.
A Proxy Ballot processing organization (Broadridge).
Intraday clearing corporations which act as a central counterparty for continuing securities settlement by facilitating novation of settlement obligations to themselves and offsetting opposing obligations (known as netting or clearing). These organizations include FICC, NSCC, etc.
The facilities which operate the national price quotation system.

Major Exchanges

New York Stock Exchange
Nasdaq The exchange platform is owned by The NASDAQ OMX Group, which also owns the OMX stock market network and several other U.S. stock and options exchanges.
COMEX (Commodity Exchange, Inc.), a division of the New York Mercantile Exchange (NYMEX)

The Federal Deposit Insurance Corporation, the Office of the Comptroller of Currency, the Federal Reserve Board of Governors, and the Federal Open Market Committee all together impact the payment systems used for settlement on securities markets, both directly by regulations and indirectly via monetary policy which affects the value of the dollar.

The Commodity Futures Trading Commission (CFTC) is an important regulator for commodities futures and options. The U.S. Securities and Exchange Commission (SEC) is the most important federal regulator of corporate stocks, as well as other securities.

One of the most important elements of the National Market System is that all qualified trades are reported onto a consolidated system.