The Board of Trustees (Board) of the Fund has approved the appointment of Los Angeles Capital Management LLC (“Los Angeles Capital”) as a sub-advisor to the Optimum Large Cap Growth Fund. It is currently anticipated that Los Angeles Capital will replace ClearBridge Investments, LLC (“ClearBridge”) as a sub-advisor to this Fund in mid-January 2023.

On or about mid-January 2023, in connection with the appointment of Los Angeles Capital as a sub-advisor to the Fund, the following will replace the information in the sections of the Fund’s prospectus entitled "Fund summaries: Optimum Large Cap Growth Fund – What are the Fund's principal investment strategies?" and "Fund summaries: Optimum Large Cap Growth Fund – Who manages the Fund? – Sub-advisors”:

What are the Fund’s principal investment strategies?

Under normal circumstances, the Fund will invest at least 80% of its net assets, plus the amount of any borrowings for investment purposes, if any, in equity securities of large market capitalization companies (80% policy). This policy may be changed only upon 60 days’ prior notice to shareholders. For purposes of this Fund, large market capitalization companies are those companies whose market capitalization is similar to the market capitalization of companies in the Russell 1000^® Growth Index. As of June 30, 2022, the Russell 1000 Growth Index (Index) had a market capitalization range between $328.0 million and $2.216 trillion. The market capitalization range for this Index will change on a periodic basis. A company’s market capitalization is based on its current market capitalization or its market capitalization at the time of the Fund’s investment. Companies whose market capitalization no longer meets this definition after purchase continue to be considered to have a large capitalization for purposes of this 80% policy. Frank Russell Company is the source and owner of the trademarks, service marks, and copyrights related to the Russell Indexes. Russell^® is a trademark of Frank Russell Company.

The Fund intends to invest primarily in common stocks of US companies, but it may also invest in other securities that a sub-advisor believes provide opportunities for capital growth, such as preferred stocks, warrants, and securities convertible to common stocks. In keeping with the Fund’s investment objective, the Fund may also invest in foreign securities, including American depositary receipts (ADRs) and other depositary receipts and shares; derivatives, including futures and options; and fixed income securities, including those rated below investment grade.

The Fund’s manager, Delaware Management Company (Manager), has selected American Century Investment Management, Inc. (“American Century”) and Los Angeles Capital Management LLC to serve as the Fund’s sub-advisors. Each sub-advisor is responsible for the day-to-day investment management of the portion of the Fund’s assets that the Manager allocates to the sub-advisor. The Manager may change the allocation at any time. The relative values of each sub-advisor’s share of the Fund’s assets also may change over time. Each sub-advisor selects investments for its portion of the Fund based on the sub-advisor’s own investment style and strategy.

The portfolio managers of American Century look for stocks of larger-sized companies they believe will increase in value over time. The portfolio managers use a bottom-up approach to stock selection. This means that the portfolio managers make their investment decisions based primarily on their analysis of individual companies, rather than on broad economic forecasts. Management of their portion of the Fund is based on the belief that, over the long term, stock price movements follow growth in earnings, revenues and/or cash flow.

Using a variety of analytical research tools, the portfolio managers of American Century track financial information for individual companies to identify and evaluate trends in earnings, revenues and other business fundamentals. Under normal market conditions, the portfolio managers seek securities of companies whose earnings and revenues are not only growing but growing at an accelerated pace. This includes companies whose growth rates, although still negative, are less negative than prior periods, and companies whose growth rates are expected to accelerate. Among other variables, the portfolio managers will consider their portion of the Fund’s growth and momentum profile relative to the benchmark. Other analytical techniques help identify additional signs of business improvement, such as increasing cash flows, or other indications of the relative strength of a company’s business. In addition to accelerating growth and other signs of business improvement, the portfolio managers of American Century also consider companies demonstrating price strength relative to their peers. This means that the portfolio managers favor companies whose securities are the strongest performers compared to the overall market. These techniques help the portfolio managers buy or hold the stocks of companies they believe have favorable growth prospects and sell the stocks of companies whose characteristics no longer meet their criteria.

In managing its portion of the Fund’s assets, Los Angeles Capital uses a proprietary quantitative model that includes fundamental data inputs for a universe of large cap equity securities and, through the use of statistical tools, estimates expected returns based on each security’s risk characteristics and the expected return to each characteristic in the current market environment. Security weights are assigned through an integrated optimization process which identifies the portfolio with the highest expected return for an acceptable level of risk. Los Angeles Capital also employs monitoring tools and certain additional constraints to ensure compliance with guidelines and Fund regulations. The portfolio is rebalanced periodically using the quantitative model. As economic conditions change and investor risk preferences evolve, Los Angeles Capital’s forecasts will change accordingly. Los Angeles Capital will ordinarily seek to almost fully invest its segment of the Fund’s portfolio.

In response to market, economic, political, or other conditions, a sub-advisor may temporarily use a different investment strategy for defensive purposes. If a sub-advisor does so, different factors could affect the Fund’s performance and the Fund may not achieve its investment objective. The Fund’s investment objective is nonfundamental and may be changed without shareholder approval. However, the Fund’s Board of Trustees (Board) must approve any changes to nonfundamental investment objectives, and the Fund’s shareholders would be given at least 60 days’ notice prior to any such change.

Who Manages the Fund? - Sub-advisors

American Century Investment Management, Inc.

Los Angeles Capital Management LLC

Portfolio manager	Title with Los Angeles Capital	Start date on the Fund
Hal W. Reynolds	Co-Chief Investment Officer, Senior Portfolio Manager	January 2023
Daniel Arche	Director, Portfolio Strategy and Senior Portfolio Manager	January 2023
Daniel E. Allen	Chief Executive Officer and Senior Portfolio Manager	January 2023