XCBU seeks to provide income by replicating, to the extent possible, the performance of an index which is a diversified representation of the U.S dollar-denominated investment grade corporate bond market, net of expenses. XCBU currently seeks to replicate the performance of the iBoxx USD Liquid Investment Grade Index. Under normal market conditions, XCBU will primarily invest in securities of one or more iShares ETFs and/or U.S. fixed income securities.