DEFINITION of 'Commodity Index'
An index that tracks a basket of commodities to measure their performance. These indexes are often traded on exchanges, allowing investors to gain easier access to commodities without having to enter the futures market. The value of these indexes fluctuates based on their underlying commodities, and this value can be traded on an exchange in much the same way as stock index futures.
BREAKING DOWN 'Commodity Index'
There is a wide range of indexes on the market, each of them varying by their components. The Reuters/Jefferies CRB Index, which is traded on the NYBOT, comprises 19 different types of commodities ranging from aluminum to wheat. They also vary in the way they are weighted; some indexes, for instance, are equally weighted and others have a predetermined, fixed weighting scheme.