The Fund seeks to track the investment results, before fees and expenses, of the ICE BofA BB-B U.S. Cash Pay High Yield Constrained Index (the Index), which is comprised of U.S. dollar-denominated below-investment grade publicly issued corporate debt in the U.S. that are currently in a coupon paying period and are rated BB1 through B3, based on an average of Moodys Investors Services, Inc. (Moodys), S&P Global Ratings (S&P) and Fitch Ratings, Inc. (Fitch), but caps issuer exposure at 2 percent. Index constituents are capitalization-weighted, based on their current amount outstanding, provided the total allocation to an individual issuer does not exceed 2 percent. Issuers that exceed the limit are reduced to 2 percent and the face value of each of their bonds is adjusted on a pro-rata basis. Similarly, the face values of bonds of all other issuers that fall below the 2 percent cap are increased on a pro-rata basis. In the event there are fewer than 50 issuers in the Index, each is equally weighted and the face values of their respective bonds are increased or decreased on a pro-rata basis. A substantial portion of Index constituents may be restricted securities, including Rule 144A securities. Neither Nuveen Asset Management, LLC, the Funds sub-adviser (the sub-adviser) nor its affiliates have any discretion to select Index or Base Index components or change the Indexs or Base Indexs methodologies. As of July 31, 2025, the Index was comprised of 1,654 securities.