The difference in price between equivalent amounts of two commodities, securities (e.g., bonds), or currencies at two different conditions (e.g., different physical locations and/ or points in time, etc.) In commodity trading, a spread can be for the same commodity and location (e.g., the summer-winter spread for natural gas), or can be cross-commodity (e.g., the crack spread between the price of crude oil and the price of refined products.

For futures contracts, spread (spread in futures) refers to the simultaneous purchase and sale of futures contracts either for the same underlying (commodity or instrument) with different maturity months or for commodities in different but related markets (as in two differently located markets for the same commodity). Spread in futures may also involve taking a long position in a futures contract of a specific maturity and a short position in a contract of different maturity, both on an identical commodity.

In the domain of option contracts, spread (spread in options) is a combination of two call options or two put options or more on the same underlying (security) with different features (e.g., different exercise prices or times to expiration). For example, a money spread is a spread with different exercise prices, while a time spread (calendar spread) involves different expiration dates.