Suppose the spot price of crude oil is US$20 per barrel and a buyer enters into a one-day forward contract where he agrees to buy a barrel of crude oil tomorrow at US$20. A few minutes after the trade, the spot price jumps to US$21 per barrel. How much money does the buyer make? The buyer can buy a barrel of crude oil that now costs US$21 at US$20 tomorrow because of the forward contract. The US$1 increase in the spot price translates to a US$1 gain in the one-day forward position.