The investment seeks investment results that correspond (before fees and expenses) generally to the price and yield performance of its underlying index, the Alerian Midstream Energy Select Index. The underlying index is a composite of North American energy infrastructure companies engaged in midstream activities involving energy commodities including gathering and processing, liquefaction, pipeline transportation, rail terminaling, and storage (also known as "midstream energy businesses"). The fund will normally invest at least 90% of its total assets in securities that comprise the underlying index. It is non-diversified.