Although many broker-dealers are "independent" firms solely involved in broker-dealer services, many others are business units or subsidiaries of commercial banks, investment banks or investment companies.
When executing trade orders on behalf of a customer, the institution is said to be acting as a broker. When executing trades for its own account, the institution is said to be acting as a dealer. Securities bought from clients or other firms in the capacity of dealer may be sold to clients or other firms acting again in the capacity of dealer, or they may become a part of the firm's holdings.
Main points of activity 
- Professional participant in securities market who carries out dealer activity shall be called dealer.
- Announcing the price, the dealer is committed to announce other essential conditions of the buy-sell contract of securities: minimum and maximum number of securities subject to purchase and/or sale, as well as the term of announced prices validity.
- All the functions of broker including financial consulting
- Organization and support of turnover (liquidity), or so-called market-making (price announcing, duty of sell and buy of security at announced price, announcing of min and max number of securities that can be bought/sold at announced price, implementing time periods when announced prices are available)
In the United States, broker-dealers are regulated under the Securities Exchange Act of 1934 by the Securities and Exchange Commission (SEC), a unit of the U.S. government. Some regulatory authority is further delegated to the Financial Industry Regulatory Authority (FINRA), a self-regulatory organization. Many states also regulate broker-dealers under separate state securities laws (called "blue sky laws").
The 1934 Act defines "broker" as "any person engaged in the business of effecting transactions in securities for the account of others," and defines "dealer" as "any person engaged in the business of buying and selling securities for his own account, through a broker or otherwise." Under either definition, the person must be performing these functions as a business; if conducting similar transactions on a private basis, they are considered a trader and subject to different requirements.
On April 28, 2004, the SEC voted unanimously to change the net capital rule which applies to broker-dealers, thus allowing those with "tentative net capital" of more than $5 billion to increase their leverage ratios. Many commentators have cited this rule change as an important factor in the financial crisis that began in 2007. The rule change remains in effect, though subject to modifications.
UK securities law uses the term intermediary to refer to businesses involved in the purchase and sale of securities for the account of others.
The common Japanese term for a broker-dealer is "securities company" (証券会社 shōken-gaisha ). Securities companies are regulated by the Financial Services Agency under the Financial Instruments and Exchange Law. The "big three" are Nomura Holdings, Daiwa Securities Group and Nikko Cordial (a subsidiary of Sumitomo Mitsui Financial Group). Most major commercial banks in Japan also maintain broker-dealer subsidiaries, as do many foreign commercial banks and investment banks.
See also 
- NASAA Broker-Dealer Resources
- Guide to Broker-Dealer Registration, Division of Trading and Markets, U.S. Securities and Exchange Commission, April 2008.
- General Accounting Office, Major Rule Report: Alternative Net Capital Requirements for Broker-Dealers That Are Part of Consolidated Supervised Entities (B-294184), June 25, 2004. (“GAO Major Rule Report”)
- Financial Services and Markets Act 2000, schedule 2