Invesco DB Base Metals Fund(AMEX:DBB)

DBB reflects the performance of industrial-metals commodity futures. As a commodity pool, it holds a basket of futures directly, but also distributes a complicated K-1 tax form at year-end. DBB holds just three equally weighted metals aluminum, copper and zinc. That sets it apart from its production-weighted benchmark, which also includes nickel and lead, and DBB's equal weighting strategy gives zinc a sizeable bump at the expense of copper. DBB optimizes its contract selection to minimize the effects of contango, though that could also make it less sensitive to spot prices compared to a front-month strategy. The fund and the index are rebalanced and reconstituted annually in November.