Commodity index funds are playing a growing role in retail investor portfolios. In many ways, investors have viewed commodity trading as the purview of large investors, the very wealthy and the highly leveraged. These spot trades bring to mind rough men on a trading floor shouting the prices of pork-belly futures. Some direct commodity markets are virtual, in that commodities such as energy are traded and the trades executed real time. Instead of the real-time trades required of the direct c...