margin :

Allows investors to buy securities by borrowing money from a broker. The margin is the difference between the market value of a stock and theloan a broker makes. Related: Security deposit (initial). In the context of hedging and futures contracts, the cash collateral deposited with a trader or exchanged as insurance against default.

Margin :

The percentage of deposit required by a broker to start a transaction, allowing traders to invest a larger amount of capital than they have to hand. See leverage.