To achieve its objective the Fund invests at least 80 percent of its investable assets in U.S. dollar-denominated collateralized loan obligations (CLOs) that are, at the time of purchase, rated AAA (or equivalent) by at least one nationally recognized statistical rating organization (NRSRO) or, if unrated, determined by the subadviser to be of comparable quality as well as in securities or other instruments that provide similar investment or risk exposure to AAA rated CLOs. For purposes of compliance with the 80 percent policy, the Fund may invest in other registered funds (including ETFs) or collective investment vehicles that invest principally in CLOs rated AAA (or equivalent) by at least one NRSRO (or, if unrated, determined to be of comparable quality). In addition, the Fund employs a duration overlay (as described below), consisting of longer-duration fixed-income instruments, and may use derivatives, including but not limited to, U.S. Treasury futures, interest rate swaps and options on interest rate instruments.