The following bar chart and table give some indication of the risks of investing in the Fund by showing changes in the performance of the Fund’s Class Y-3 shares from year to year and comparing the Fund’s average annual returns over time with a broad-based securities market index, the Russell 2500^® Index.

The Fund offers four different classes of shares in this prospectus: Adviser Class shares, Class I shares, Class Y-2 shares and Class Y-3 shares. No information is shown for Adviser Class or Class Y-2 shares because there were no shares outstanding for these classes as of the last calendar year end. Performance information for these share classes will appear in a future version of the prospectus once there is a full calendar year of performance information to report. The returns of these share classes would have been substantially similar to the returns of Class Y-3 shares; however, because the Adviser Class, Class I and Class Y-2 shares are subject to a 12b-1 fee and/or a non-distribution shareholder administrative services fee, the returns of these share classes would have been lower than those shown for Class Y-3 shares.

The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. This may be particularly true given that other subadvisers were responsible for managing portions of the Fund’s portfolio during previous periods. Westfield Capital Management Company, L.P. assumed responsibility for managing a portion of the Fund’s portfolio on August 15, 2005. Parametric Portfolio Associates LLC assumed responsibility for managing a portion of the Fund’s portfolio on February 25, 2015. Effective June 27, 2016, the Fund changed certain of its subadvisers and revised its principal investment strategies. For periods prior to June 27, 2016, the Fund’s past performance in the bar chart and table reflects the Fund’s prior subadviser lineup and principal investment strategies. GW&K Investment Management, LLC, Loomis, Sayles & Company, L.P. and LSV Asset Management each assumed responsibility for managing a portion of the Fund’s portfolio on July 1, 2016. River Road Asset Management, LLC assumed responsibility for managing a portion of the Fund’s portfolio on April 30, 2019.

Mercer US Small/Mid Cap Equity Fund – Class I Shares

The Fund’s calendar year-to-date return as of June 30, 2026 was 9.32%.

The Fund’s highest return for a quarter during the periods shown above was 17.38%, for the quarter ended June 30, 2020.

The Fund’s lowest return for a quarter during the periods shown above was -22.39%, for the quarter ended March 31, 2020.

The Fund’s calendar year-to-date return as of June 30, 2026 was 24.30%

The Fund’s highest return for a quarter during the period shown above was 20.03%, for the quarter ended June 30, 2020.

The Fund’s lowest return for a quarter during the period shown above was -25.65%, for the quarter ended March 31, 2020.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. In some cases, the after-tax returns may exceed the return before taxes due to an assumed benefit from any losses on a sale of shares at the end of the measurement period. After-tax returns are shown for Class Y-3 shares. After-tax returns for Class I shares may vary.

The following bar chart and table give some indication of the risks of investing in the Fund by showing changes in the performance of the Fund’s Class Y-3 shares from year to year and comparing the Fund’s average annual returns over time with a broad-based securities market index, Bloomberg U.S. Aggregate Bond Index.

The Fund offers four different classes of shares in this prospectus: Adviser Class shares, Class I shares, Class Y-2 shares and Class Y-3 shares. No information is shown for Adviser Class or Class Y-2 shares because there were no shares outstanding for these classes as of the last calendar year end. Performance information for Adviser Class shares and Class Y-2 shares will appear in a future version of the prospectus once there is a full calendar year of performance information to report. The returns of these share classes would have been substantially similar to the returns of Class Y-3 shares; however, because the Adviser Class and Class Y-2 shares are subject to a 12b-1 fee and/or a non-distribution shareholder administrative services fee, the returns of these share classes would have been lower than those shown for Class Y-3 shares.

The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. This may be particularly true given that other subadvisers were responsible for managing portions of the Fund’s portfolio during previous periods. Income Research + Management assumed responsibility for managing a portion of the Fund’s portfolio on April 3, 2014. PGIM, Inc. assumed responsibility for managing a portion of the Fund’s portfolio on April 3, 2014. Manulife Investment Management (US) LLC assumed responsibility for managing a portion of the Fund’s portfolio on June 1, 2016.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-deferred arrangements, such as 401(k) plans

or individual retirement accounts. In some cases, the after-tax returns may exceed the return before taxes due to an assumed benefit from any losses on a sale of shares at the end of the measurement period. After-tax returns are shown for Class Y-3 shares. After-tax returns for Class I shares may vary.

The following bar chart and table give some indication of the risks of investing in the Fund by showing changes in the performance of the Fund’s Class Y-3 shares from year to year and comparing the Fund’s average annual returns over time with a broad-based securities market index, Bloomberg U.S. Aggregate Bond Index. The Fund’s average annual returns over time are also compared to an additional blended benchmark consisting of 33.3% Bloomberg US Corporate High Yield Index (USD), 33.3% Morningstar LSTA US Leveraged Loan Index and 33.3% JP Morgan EMBI Global Diversified Index (USD).

The Fund offers four different classes of shares in this prospectus: Adviser Class shares, Class I shares, Class Y-2 shares and Class Y-3 shares. No information is shown for Adviser Class or Class Y-2 shares because there were no shares outstanding for these classes as of the last calendar year end. Performance information for these share classes will appear in a future version of the prospectus once there is a full calendar year of performance information to report. The returns of these share classes would have been substantially similar to the returns of Class Y-3 shares; however, because the Adviser Class, Class I and Class Y-2 shares are subject to a 12b-1 fee and/or a non-distribution shareholder administrative services fee, the returns of these share classes would have been lower than those shown for Class Y-3 shares.

The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. This may be particularly true given that other subadvisers were responsible for managing portions of the Fund’s portfolio during previous periods. Ninety One North America, Inc. assumed responsibility for managing a portion of the Fund’s portfolio on June 15, 2023. Ares Capital Management II LLC, Crescent Capital Group LP and Polen Capital Credit, LLC assumed responsibility for managing portions of the Fund’s portfolio on April 15, 2025. Pacific Investment Management Company LLC and Wellington Management Company LLP assumed responsibility for managing portions of the Fund’s portfolio on April 29, 2025.

The Fund’s calendar year-to-date return as of June 30, 2026 was 2.27%.

The Fund’s highest return for a quarter during the period shown above was 9.57%, for the quarter ended June 30, 2020.

The Fund’s lowest return for a quarter during the period shown above was -10.10%, for the quarter ended March 31, 2020.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates in effect and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. In some cases, the after-tax returns may exceed the return before taxes due to an assumed benefit from any losses on a sale of shares at the end of the measurement period. After-tax returns are shown for Class Y-3 shares. After-tax returns for Class I shares may vary.

The following bar chart and table give some indication of the risks of investing in the Fund by showing changes in the performance of the Fund’s Class Y-3 shares from year to year and comparing the Fund’s average annual returns over time with a broad-based securities market index, the Bloomberg U.S. 1-3 Year Government/Credit Index.

The Fund offers four different classes of shares in this prospectus: Adviser Class shares, Class I shares, Class Y-2 shares and Class Y-3 shares. No information is shown for Adviser Class, Class I or Class Y-2 shares because there were no shares outstanding for these classes as of the last calendar year end. Performance information for Adviser Class shares, Class I shares and Class Y-2 shares will appear in a future version of the prospectus once there is a full calendar year of performance information to report. The returns of these share classes would have been substantially similar to the returns of Class Y-3 shares; however, because the Adviser Class, Class I and Class Y-2 shares are subject to a 12b-1 fee and/or a non-distribution shareholder administrative services fee, the returns of these share classes would have been lower than those shown for Class Y-3 shares.

The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Voya Investment Management Co. LLC, Aristotle Pacific Capital, LLC and Merganser Capital Management, LLC each assumed responsibility for managing a portion of the Fund’s portfolio on December 1, 2023.