The fund normally invests at least 80% of assets in securities included in the Bloomberg U.S. Long Treasury Bond Index. It normally maintains a dollar-weighted average maturity that generally is expected to be 10 years or more, consistent with that of the index. The advisor uses statistical sampling techniques based on duration, maturity, interest rate sensitivity, security structure, and credit quality to attempt to replicate the returns of the Bloomberg U.S. Long Treasury Bond Index using a smaller number of securities.