This fund aims to replicate the investment performance of the Bloomberg Barclays December 2020 Maturity Corporate Index, also known as its "underlying index." Typically, it commits a minimum of 90% of its assets to the component bonds within this benchmark. The underlying index itself is composed of U. S. dollar-denominated, taxable, investment-grade corporate debt instruments, specifically those with maturities scheduled between December 31, 2019, and December 16, 2020.