The Municipal Securities Rulemaking Board (MSRB) is a self-regulatory organization (SRO) that is subject to Securities and Exchange Commission (SEC) oversight. The MSRB regulates the municipal securities market, which is composed of entities that issue municipal securities and the broker-dealers and banks that underwrite, trade and sell those securities. The MSRB was established in 1975 by Congress to develop rules regulating the municipal securities market. The MSRB is governed by a 21-member board of directors, with 11 members representing the public and 10 members representing regulated entities. The MSRB operates the Electronic Municipal Market Access (EMMA) system, which provides free public access to official disclosures, trade data and other information related to the municipal securities market. The MSRB is headquartered in Washington, D.C.