RE:oil futures
https://www.investopedia.com/university/futures/futures2.asp do a Google search on "how do futures work" Profit And Loss - Cash Settlement The profits and losses of a futures contract depend on the daily movements of the market for that contract and are calculated on a daily basis. For example, say the futures contracts for wheat increases to $5 per bushel the day after the above farmer and bread maker enter into their futures contract of $4 per bushel. The farmer, as the holder of the short position, has lost $1 per bushel because the selling price just increased from the future price at which he is obliged to sell his wheat. The bread maker, as the long position, has profited by $1 per bushel because the price he is obliged to pay is less than what the rest of the market is obliged to pay in the future for wheat. On the day the change occurs, the farmer's account is debited $5,000 ($1 per bushel X 5,000 bushels) and the bread maker's account is credited by $5,000 ($1 per bushel X 5,000 bushels). As the market moves every day, these kinds of adjustments are made accordingly. Unlike the stock market, futures positions are settled on a daily basis, which means that gains and losses from a day's trading are deducted or credited to a person's account each day. In the stock market, the capital gains or losses from movements in price aren't realized until the investor decides to sell the stock or cover his or her short position.