A commodity swap which allows a refiner to hedge against a narrowing spread between crude oil prices and the prices of its refined products. Therefore, the right to profit from a potential widening of the spread is given up. This swap can effectively lock in a margin (known as a crack spread) by paying the floating price of a refined oil product and receiving the floating price of a crude oil input plus the crack spread.

The refinery margin swap is also known as a crack spread swap.