Under normal market conditions, the Fund invests at least 80% of its net assets in direct obligations of the U.S. Treasury, including Treasury bonds, bills and notes, and investments that provide exposure to direct obligations of the U.S. Treasury. The Fund may invest in U.S. Treasury securities of any maturity and intends to primarily focus on U.S. Treasury securities with a remaining maturity of between 1-30 years. The Fund may also invest in securities issued or guaranteed by the U.S. government, its agencies, or instrumentalities, including government sponsored entities and mortgage-backed securities. A mortgage-backed security is an interest in a pool of mortgage loans made and packaged or pooled together by banks, mortgage lenders, various governmental agencies and other financial institutions for sale to investors to finance purchases of homes, commercial buildings and other real estate. The Funds investments in mortgage-backed securities include securities that are issued or guaranteed by the U.S. government, its agencies or instrumentalities, which include mortgage passthrough securities representing interests in pools of mortgage loans issued or guaranteed by the Government National Mortgage Association (Ginnie Mae), the Federal National Mortgage Association (Fannie Mae), and the Federal Home Loan Mortgage Corporation (Freddie Mac). The mortgage securities the Fund invests in may be fixed-rate or adjustable-rate mortgage-backed securities (ARMS). The Fund may also purchase or sell mortgage securities on a delayed delivery or forward commitment basis through the to-be-announced (TBA) market. With TBA transactions, the particular securities to be delivered must meet specified terms and conditions. To pursue its investment goal, the Fund may enter into certain interest rate-r