The fund seeks to generate, over time, a level of income higher than that generated by high-quality, intermediate-term U.S. debt securities. The fund normally invests at least 80% of its net assets (plus any borrowings for investment purposes) in a combination of income-producing securities of non-corporate issuers, such as securities issued or guaranteed by the U.S. or foreign governments, mortgage-related and other asset-backed securities issued on a public or private basis, corporate debt obligations, and other income-producing securities of varying maturities issued by U.S. or foreign (non-U.S.) corporations or other business entities, including emerging market issuers and municipal securities.