- The maximum amount of money controlled by an investor at any one time. This can be substantially more than the total amount of money invested because of the various leverage mechanisms at work. For stocks, leverage control is typically 2 to 1. Most Forex trading is done through margin. The typical FX margin ratio is 100:1 or 1%. It can be as high as 200:1. This means for every dollar invested, the trader can control up to 200 dollars worth of currencies through margin instruments.