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Margin - The required equity that an investor must deposit to collateralize a position.
Margin Call - A request from a broker or dealer for additional funds or other collateral to guarantee performance on a position that has moved against the customer.
Market Maker - A dealer who regularly quotes both bid and ask prices and is ready to make a two-sided market for any financial instrument.
Market Risk - Exposure to changes in market prices.
Mark-to-Market - Process of re-evaluating all open positions with the current market prices. These new values then determine margin requirements.
Maturity - The date for settlement or expiry of a financial instrument.