About the Chicago Mercantile Exchange :
The CME is one of the few exchanges that still utilize the open outcry system of trading. Under this system, the traders all gather on the trading floor and call out their bids and offers. Different colored jackets are used to distinguish the various participants, and hand signals are also often used, as the shouting can make it hard to hear. The exchange has two main trading floors, one for the foreign currency and interest rate derivatives and another for the agricultural commodities and stock index derivatives. The CME also utilizes electronic trading, using GLOBEX2. This system allows for 24 hour trading while also allowing traders who are not physically located on the Chicago trading floor to participate.