M
MARAD - Maritime Administration
MBCC - Migratory Bird Conservation Commission (agency dealing with the preservation of habitat, lands and waterways and issues related to migratory birds)
MBSCC - Mortgage-Backed Securities Clearing Corporation (Securities and Exchange Commission (SEC)-registered clearing corporation that provides services to the mortgage-backed securities market)
MDA - Missile Defense Agency (agency within the Department of Defense (DoD) dealing with technology, systems, and maintenance of the U.S. missile defense system)
MFN - Most Favored Nation (tariff regulations under which certain countries are granted especially favorable or more favorable tariff rate treatment than others)
MHR - Member of the U.S. House of Representatives
MMS - Minerals Management Service (former name of the Interior Department agency dealing with oversight of resource development and industry operations in U.S. waters)
MPSA - Military Postal Service Agency (agency providing postal/mail delivery service to the military service branches)
MSHA - Mine Safety and Health Administration (agency responsible for studying safety and health issues in the mining industry)
MSPB - Merit Systems Protection Board (agency which deals with civil service employment/jobs issues)
MSRB - Municipal Securities Rulemaking Board (body created under the Securities Acts Amendments of 1975 to regulate brokers, dealers, and banks dealing in municipal securities)