DBC represents 14 commodities drawn from the Energy, Precious Metals, Industrial Metals and Agriculture sectors via futures contracts. The funds index aims to maximize the potential roll benefits in backwardation markets and minimize any loss from rolling down the curve in contango markets. It did so by employing a rules-based approach when it rolls from one futures contract to another for each commodity. Rather than rolling based on a predefined schedule (e.g. monthly), the index rolls to futures (within the next 13) which, by its rules, generates the maximum implied roll yield. Structured as a commodity pool, investors should expect a K-1 at tax time. The fund and the index are rebalanced and reconstituted annually in November.