VPU is designed to track an all-cap index of US electric, gas, and water utility companies. The index is market-cap weighted index and subject to capping limitations. The capping is designed to ensure diversity among its portfolio by limiting the weight of a single issuer to 25% of the funds assets. The fund may also hold independent power producers, energy traders and companies engaged in electricity using renewable sources. VPU attempts to replicate the target index by seeking to invest all, or substantially all, of its assets in the stocks that make up the Index, in order to hold each stock in approximately the same proportion as its weighting in the Index. The index is rebalanced quarterly.