Crack spread is a term used on the oil industry and futures trading for the differential between the price of crude oil and petroleum products extracted from it. The spread approximates the profit margin that an oil refinery can expect to make by "cracking" the long-chain hydrocarbons of crude oil into useful shorter-chain petroleum products. In the futures markets, the "crack spread" is a specific spread trade involving simultaneously buying and selling contracts in crude oil and one or more derivative products, typically gasoline and heating oil. Oil refineries may trade a crack spread to hedge the price risk of their operations, while speculators attempt to profit from changes in the oil/gasoline price differential. Factors affecting the crack spread One of the most important factors affecting the crack spread is the relative proportion of various petroleum products produced by a refinery. Refineries produce many products from crude oil, including gasoline, kerosene, diesel, heating oil, aviation fuel, bitumen and others. To some degree, the proportion of each product produced can be varied in order to suit the demands of the local market. Regional differences in the demand for each refined product depend upon the relative demand for fuel for heating, cooking or transportation purposes. Within a region, there can also be seasonal differences in demand for heating fuel versus transportation fuel. The mix of refined products is also affected by the particular blend of crude oil feedstock processed by a refinery, and by the capabilities of the refinery. Heavier crude oils contain a higher proportion of heavy hydrocarbons composed of longer carbon chains. As a result, heavy crude oil is more difficult to refine into lighter products such as gasoline. A refinery using less sophisticated processes will be constrained in its ability to optimize its mix of refined products when processing heavy oil. Futures trading For integrated oil companies that control their entire supply chain from oil production to retail distribution of refined products, their business provides a natural economic hedge against adverse price movements. For independent oil refiners which purchase crude oil and sell refined products in the wholesale market, adverse price movements can present a significant economic risk. Given a target optimal product mix, an independent oil refiner can attempt to hedge itself against adverse price movements by buying oil futures and selling futures for its primary refined products according to the proportions of its optimal mix. For simplicity,