Macroeconomics
The field of economic sciences dealing with the functions of entire economies (countries, regions, etc), looking at aspects like prices, trade, GDP, employment etc.
Margin
the difference between input and output. Often used for the difference between revenue and cost of a product or a service. In finance, multiple uses exist for the term. The interest margin determines the difference between interest banks have to pay and what they can lend for. Margin is also used as the term for collateral pledged by a borrower for a loan.
Mark-to-market
The valuation of (mostly) securities according to their current market value. When a bank (or any other holder of a security) marks its value according to market, it is valued according to what the market currently would pay for that security. This can lead to significant fluctuations. The alternative approach is to mark to maturity, e.g. to value a security according to the value it will yield once it matures, e.g. the borrower will pay it back.
Microeconomics
The field of economic science dealing with decisions of individual participants in an economic exchange or decision making process.
Money Supply
The money available in an economy. Various levels are determined, starting from available cash (M0) to broadest definitions including all holdings of money or money equivalents in an economy.
Mortgage-Backed Security
Mortgage-Backed Security