Diamonds and Cubes

Only a day trader can understand the adrenaline rush that comes from jumping in and out of the market all day long, watching instantaneous stock prices stream across the computer screen, taking a position and minutes later dumping it. They live a life of high-octane excitement, shaving an eighth of a point here, six cents there, and hoping to finish the day ahead of where they started.

Nick Anthony is the owner of a firm in San Diego called Market Makers, where he rents out work stations to...