For example, you decide to go short one near-month NYMEX Gold Futures contract at the price of USD 851.00/oz. Since each Gold futures contract represents 100 troy ounces of gold, the value of the contract is USD 85,100. To enter the short futures position, you have to put up an initial margin of USD 4,302.
A week later, the price of gold falls and correspondingly, the price of NYMEX Gold futures drops to USD 765.90 per troy ounce. Each contract is now worth only USD 76,590. So by closing out your futures position now, you can exit your short position in Gold Futures with a profit of USD 8,510. Quite clear.