Both the Chicago Board of Trade (CBOT) and the Chicago Mercantile Exchange (CME) trace their roots to 19th-century Chicago, where each began as a nonprofit market for agricultural transactions. While the two shared many historical developments, they emphasized different investments and operated in different fashions until their merger into CME Group, which also includes the NYMEX and COMEX as part of its four designated contracts markets.

The merger between the two exchanges occurred in 2006 in a move approved by shareholders of both organizations. Up until that merger, they employed substantially different rules, regulations, market offerings and trading engines.

The Chicago Board of Trade is the oldest operating futures and options exchange in the world. Established in 1848 as a trading floor for grain merchants in Chicago, by 1859, the CBOT was granted a charter from the state legislature in Illinois and grew into a prominent agricultural futures market.

In fact, the concept of exchanging forward contracts in a "futures market" may have originated at the CBOT in the 1860s. This investment hub also helped to popularize "open outcry" trading floors; traders met in the octagon-shaped "pits" to literally shout (or gesture) to make offers on stocks or futures contracts in a public setting, helping set markets on the exchange. Open outcry trading was replaced at the CBOT in 1994 by an electronic system of placing orders.

After more than 125 years of trading exclusively in agricultural products, financial contracts were added to the Chicago Board of Trade in 1975. Financial futures contracts followed in 1982, and then futures-options contracts in 1997. It is a popular exchange for trading on a variety of instruments, including precious metals, government securities and energy stocks.

The CBOT was reorganized in 2005 and held an initial public offering on the New York Stock Exchange as the Chicago Board of Trust Holdings Inc.

The Chicago Mercantile Exchange was founded in 1898 as the "Chicago Butter and Egg Board" before changing its name in 1919. It is the second-largest futures and options exchange in the world and the largest in the United States. The exchange is perhaps most notable for being the first financial exchange to "demutualize" and become a publicly traded, shareholder-owned corporation in the year 2000.

The CME launched its first futures contracts in 1961 on frozen pork bellies. More significant contract launches include financial futures and currency contracts in 1969 and the first interest rate futures contracts in 1972.

The CME is now a Designated Self-Regulatory Organization, or DSRO, and it holds regulatory/audit authority over its many subsidiary organizations. Popular investments traded at the CME include forex futures, currencies, stock indexes, interest rate futures and agricultural products.

The Chicago Mercantile Exchange, sometimes referred to as Merc, has both public outcry trading floors and an electronic trading platform called GLOBEX, where more than 70% of its transactions take place.