The Chicago Butter and Egg Board was founded in 1898 and evolved into the Chicago Mercantile Exchange (now CME) in 1919. Initially, its members traded futures contracts on agricultural commodities via open outcry. This system of trading – which is still in use today – essentially involves hundreds of auctions going on at the same time.

In open outcry trading, traders stand in a trading pit and call out prices and quantities that indicate their willingness to buy or sell. They use hand signals to convey the same information since it can be difficult to hear if everyone is shouting at once. Open outcry is an efficient means of "price discovery," allowing buyers and sellers to arrive at the best prices given the supply and demand for a given futures or options on futures contract. Its speed and efficiency have been further enhanced by the introduction of a variety of trading floor technologies.

The CME open outcry platform and trading floor systems are linked to the CME® Globex® electronic trading platform, which allows market participants to buy and sell whether they're sitting at trading booths on our Chicago trading floors, working at offices or homes thousands of miles away, or making trades during and after regular trading hours. At CME, some traders prefer face-to-face interaction on the CME trading floors while an increasing number prefer to trade electronically.