The National Association of Securities Dealers (NASD) was a self-regulatory organization (SRO) that oversaw the activities of brokers and dealers in the United States. It was created in 1939 and was responsible for regulating the over-the-counter (OTC) securities market until 2007 when it merged with the regulatory arm of the New York Stock Exchange to form the Financial Industry Regulatory Authority (FINRA).

As an SRO, the NASD was authorized by the Securities and Exchange Commission (SEC) to create and enforce rules for its members, subject to SEC oversight. The NASD was also responsible for monitoring the conduct of its members, including the handling of customer accounts, fair pricing practices, and adherence to ethical standards. It also provided educational resources and training to its members to ensure compliance with regulatory requirements.

The NASD played a crucial role in the regulation of the securities industry, especially in the OTC market, where there was less transparency and regulation than on major stock exchanges. Its duties included registering and disciplining brokers, resolving disputes between members and investors, and maintaining market integrity. The organization had the power to impose fines, suspend or expel members, and enforce compliance with its rules.

Overall, the NASD served as an important check on the behavior of brokers and dealers in the securities industry, ensuring that they acted in the best interests of their clients and upheld high standards of conduct. Its work laid the foundation for the creation of FINRA, which continues to oversee the activities of brokers and dealers in the securities industry today.