The fund will invest at least 80% of its assets in the component securities of the underlying index and to-be-announced transactions (“TBAs”) that have economic characteristics that are substantially identical to the economic characteristics of the component securities of the underlying index. The underlying index includes fixed-rate MBS issued by GNMA that have 30- or 15-year maturities. The index measures the performance of mortgage-backed pass-through securities issued by GNMA.