The Fund invests in fixed income securities of various maturities, yields, and qualities. Under normal circumstances, the Fund will invest at least 80 percent of its assets in bonds, which include fixed income securities such as corporate bonds; U.S. Treasury obligations and other U.S. government and agency securities; and asset-backed, mortgage-backed, and mortgage-related securities. In general, bonds purchased by the Fund will have a maturity of 90 days or more at the time of their issuance. In addition, the Fund invests predominantly in U.S. dollar-denominated bonds, although these bonds may be issued by a foreign corporation or a U.S. affiliate of a foreign corporation, or a foreign government or its agencies and instrumentalities. The Fund may also invest up to 10 percent of its assets in non-U.S. dollar-denominated bonds. The Fund may make use of the unique features of the ETF structure, such as in-kind transactions and custom baskets, to select securities.