English: Taken at Interactive Brokers. I took this photo myself, on July 18, 2014, with my Nikon D90 camera.

From an IB trader:

Each color represents a number from 0-9:

• 0-black
• 1-pink
• 2-light blue
• 3-dark blue w/ white stripe
• 4-white
• 5-red
• 6-gray
• 7-brown w/ yellow stripe
• 8-green
• 9-yellow

The first bar is the ‘handle’ or the dollar number, and the second bar is the fraction denominated in eighths or sixteenths. A normal size bar indicates eighths whereas a bar 1.5x the normal size means you must add 1/16 to the original fraction. Consequently a normal sized pink bar is 1/8 and a large pink bar is 3/16.

Therefore a bar of:

• black preceding a bar of red = (0,5) = (0,5/8) = 5/8
• brown w/ yellow stripe preceding light blue = (7,2) = (7,2/8) = 7.25
• pink,gray = (1,6) = (1,6/8) = 1.75

We used these screens to communicate Timber Hill’s fair market values to our traders who were often 20-30 feet away from the television screens and no hand held devices existed or were allowed until the early 1990s.

Sometimes we were prohibited from using even TV screens so we had to communicate all data from a clerk at our booth to the trader on the floor using hand signals. In that case, a trader would signal a quote he desired (i.e. – how are the Aug 25 calls?), and the clerk would respond (1 1/4 - 1 5/8). This meant that TH would buy a certain size of those calls paying 1.25 and would sell the same calls no lower than 1.625. The TH trader would then attempt to trade under those parameters and would then signal back to the clerk as to how many he BOT/SLD, and the clerk would manually input the trade into the touch screen so that the risk would be loaded into the trading system which could then change other prices and start the hedging process. As you can imagine, there were lots of frayed nerves and lots of errors.