Private, self-regulatory organization overseen by the US Securities & Exchange Commission.

http://www.msrb.org/

The MSRB is a self-regulatory organization created under the Securities Acts Amendments of 1975 . Its mission is to protect investors, municipal entities and the public interest by promoting a fair and efficient municipal market, regulating firms that engage in municipal securities and advisory activities, and promoting market transparency.

The Dodd-Frank Act of 2010 broadened the MSRB's rulemaking authority to also regulate municipal advisors, which include financial advisors, swap advisors, brokers of guaranteed investment contracts and other market participants that advise on the issuance of municipal securities. The MSRB's investor protection rules were extended to protect municipal entities as well. MSRB rules are enforced by various other federal regulatory organizations, including the SEC, FINRA, the Federal Reserve System, the Federal Deposit Insurance Corporation (FDIC) and the Office of the Comptroller of the Currency (OCC). MSRB rules do not apply to issuers of municipal securities or other municipal entities, which Congress generally exempted from most provisions of the federal securities laws.

MSRB Rules

Broker- dealers and banks in the US municipal securities market; financial advisors, swap advisors, brokers of guaranteed investment contracts and other market participants that advise on the issuance of municipal securities.

http://en.wikipedia.org/wiki/Municipal_Securities_Rulemaking_Board