A broker-dealer is a financial professional or firm that facilitates the buying and selling of securities, such as stocks and bonds. They act as intermediaries between buyers and sellers, helping clients execute trades in the financial markets. Broker-dealers can operate as either brokers, who earn commissions on trades, or dealers, who buy and sell securities for their own accounts. These entities are regulated by organizations like the Securities and Exchange Commission (SEC) in the United States to ensure fair practices and protect investors. Broker-dealers must register with the SEC and adhere to strict compliance rules to maintain transparency and integrity in their operations.