The National Association of Securities Dealers (NASD) was a self-regulatory organization in the United States that oversaw the securities industry. Established in 1939, its primary role was to create and enforce rules for brokerage firms and their registered representatives, ensuring fair practices and protecting investors. In 2007, the NASD merged with the New York Stock Exchange's regulatory arm to form the Financial Industry Regulatory Authority (FINRA). This new organization continues the mission of the NASD by regulating brokerage firms and maintaining market integrity, while also providing investor education and resources.