National association of securities dealers, inc. (NASD®)

Now known only as "NASD". The largest self-regulatory organization for the securities industry in the United States. NASD is responsible for the operation and regulation of Nasdaq and the over-the-counter securities markets. Under federal law, every securities firm doing business with the US public is a member of NASD. Roughly 5,500 brokerage firms, nearly 90,000 branch offices and more than 650,000 registered securities representatives come under its jurisdiction.