That is, if a person can purchase a good for price S and conclude a contract to sell it one month later at a price of F, the price difference should be no greater than the cost of using money less any expenses (or earnings) from holding the asset; if the difference is greater, the person has an opportunity to buy and sell the "spots" and "futures" for a risk-free profit, i.e.
If someone buys an item at price S and agrees to sell it one month later at price F, the price gap should not surpass the costs of using money minus any fees or earnings from holding the asset; if this difference is greater, the person can buy and resell "spots" and "futures" for a risk-free profit.