Hand signals on the Chicago Exchange

When I teach about financial markets, I usually show part of the PBS Nova documentary The Trillion Dollar Bet about options (this was done about ten years ago and it describes the Black-Scholes formula for pricing financial options and meltdown of LTCM - because of the current economic crisis, this is a documentary that has actually become a more useful teaching tool over time). In it there are several great scenes of the Chicago Mercantile Exchange showing the floor traders flashing hand signals at each other to make their trades. Students always ask, "How do the signals work?" and "What do the signals mean?"

Now I have the definitive answer. Ryan Carlson, a former floor trader, has setup a web page with a history, images and explanations of the hand signals. I was clued into this by the Wall Street Journal article, "Trader Keeps Hand in History".

Cool.