The fund invests at least 80% of its net assets (plus borrowings for investment purposes) in investment-grade debt instruments rated at least A by Moody's Investors Service, Inc., at least A by S&P Global Ratings, or are of comparable quality if unrated, which are at the time of purchase, included in the index; derivatives whose economic returns are, by design, closely equivalent to the returns of the index or its components; and exchange-traded funds that track the index.