Under normal market conditions, the fund invests at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in a portfolio of preferred and other income-producing securities, including traditional preferred stock, trust preferred securities, hybrid securities that have characteristics of both equity and debt securities, convertible securities, contingent-capital securities, subordinated debt, senior debt and securities of other open-end, closed-end or exchange-traded funds that invest primarily in the same types of securities.