Under normal circumstances, the Fund will invest substantially all (and at least 80%) of its net assets in bonds and other fixed-income securities included in the Index in weightings that approximate the relative composition of securities contained in the Index. The Fund will maintain a dollar-weighted average maturity consistent with the Index, which generally ranges between five to ten years.

The Index is a broad-based benchmark that measures the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market. The Index includes Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate mortgage pass-throughs), asset-backed securities, and commercial mortgage-backed securities. As of May 29, 2026, the Index was comprised of 14,173 constituents. It is rebalanced monthly. The Fund generally rebalances its portfolio in accordance with the Index.

The Fund may seek to obtain exposure to mortgage-backed and mortgage-related securities (collectively, “MBS”) through to‑be‑announced (“TBA”) transactions. Most transactions in MBS occur through TBA transactions, which are standardized contracts for future delivery in which the exact mortgage pools to be delivered are not specified until a few days prior to settlement.

NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” the index it tracks and does not seek temporary defensive positions when markets decline or appear overvalued. NTI will buy and sell securities in response to changes in the Index as well as in response to subscriptions and redemptions.

NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to that of an index. The Fund may or may not hold all

of the securities that are included in the Index. The Fund reserves the right to invest in all of the securities in the Index in approximately the same proportion (i.e., replication) if NTI determines that it is in the best interest of the Fund.

The Fund intends to be diversified in approximately the same proportion as the Index is diversified. The Fund may become “non‑diversified,” as defined in the Investment Company Act of 1940 (the “1940 Act”), solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Index. A “non‑diversified” fund can invest a greater percentage of its assets in a small group of issuers or in any one issuer than a diversified fund can Shareholder approval will not be sought if the Fund becomes non‑diversified due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Index.

In seeking to track the performance of the Index, from time to time the Fund may have a focused investment (i.e., investment exposure comprising more than 15% of its total assts) in one or more particular sectors.

NTI expects that, under normal circumstances, the quarterly performance of the Fund, before fees and expenses, will track the performance of the Index within a 0.95 correlation coefficient.

In seeking to achieve its investment objective, the Fund may invest in U.S. Treasury futures, which are considered to be derivative instruments, for various purposes, including to more closely track duration, credit and interest rate risks consistent with the Index, and for cash management purposes.