Summary Prospectus by Investment Company - Form 497K

Fixed income mutual fund

Delaware Extended Duration Bond Fund

November 29, 2024

(to be renamed Macquarie Extended Duration Bond Fund on or about December 31, 2024)

What is the Fund's investment objective?

Delaware Extended Duration Bond Fund seeks to provide investors with total return.

What are the Fund's fees and expenses?

The table below describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales-charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in Delaware Funds by Macquarie​® (to be renamed Macquarie Funds on or about December 31, 2024). More information about these and other discounts is available from your financial intermediary, in the Fund's Prospectus under the section entitled "About your account," and in the Fund's statement of additional information (SAI) under the section entitled "Purchasing Shares."

Shareholder fees (fees paid directly from your investment)

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. In addition, the example shows expenses for Class C shares, assuming those shares were not redeemed at the end of those periods. The example also assumes that your investment has a 5% return each year and reflects the Manager's expense waivers and reimbursements for the 1-year contractual period and the total operating expenses without waivers for years 2 through 10. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in the annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 86% of the average value of its portfolio.

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, in corporate bonds (80% policy). The Manager focuses on corporate bonds that have investment grade credit ratings from a nationally recognized statistical rating organization (NRSRO). The bonds the Manager selects for the portfolio are typically rated BBB- and above by Standard & Poor's Financial Services LLC (S&P), Baa3 and above by Moody's

Investors Service, Inc. (Moody's), or similarly rated by another NRSRO. The Manager may also invest in unrated bonds if it believes their credit quality is comparable to those that have investment grade ratings.

In addition, the Manager may seek investment advice and recommendations from its affiliates: Macquarie Investment Management Austria Kapitalanlage AG (MIMAK), Macquarie Investment Management Europe Limited (MIMEL), and Macquarie Investment Management Global Limited (MIMGL) (together, the "Affiliated Sub-Advisors"). The Manager may also permit these Affiliated Sub-Advisors to execute Fund security trades on behalf of the Manager and exercise investment discretion for securities in certain markets where the Manager believes it will be beneficial to utilize an Affiliated Sub-Advisor's specialized market knowledge.

The Fund may also invest up to 20% of its net assets in high yield corporate bonds ("junk bonds"). In addition, the Fund may invest up to 40% of its total assets in foreign securities, but the Fund's total non-US-dollar currency exposure will be limited, in the aggregate, to no more than 25% of net assets.

The average portfolio duration of the Fund will generally vary within two years (plus or minus) of the current average duration of the Bloomberg Long US Corporate Index, which as of December 31, 2023, was approximately 13.05 years. Duration measures a bond's sensitivity to interest rates by indicating the approximate change in a bond or bond fund's price given a 1% change in interest rates. In general, securities with longer durations are more sensitive to interest rate charges.

The 80% policy is nonfundamental and may be changed without shareholder approval. Fund shareholders would be given at least 60 days' notice prior to any such change.

What are the principal risks of investing in the Fund?

Investing in any mutual fund involves the risk that you may lose part or all of the money you invest. Over time, the value of your investment in the Fund will increase and decrease according to changes in the value of the securities in the Fund's portfolio. An investment in the Fund may not be appropriate for all investors. The Fund's principal risks include:

Market risk - The risk that all or a majority of the securities in a certain market - such as the stock or bond market - will decline in value because of factors such as adverse political or economic conditions, future expectations, investor confidence, or heavy institutional selling.

Interest rate risk - The risk that the prices of bonds and other fixed income securities will increase as interest rates fall and decrease as interest rates rise. Interest rate changes are influenced by a number of factors, such as government policy, monetary policy, inflation expectations, and the supply and demand of bonds. Bonds and other fixed income securities with longer maturities or duration generally are more sensitive to interest rate changes. A fund may be subject to a greater risk of rising interest rates when interest rates are low or inflation rates are high or rising.

Credit risk - The risk that an issuer of a debt security, including a governmental issuer or an entity that insures a bond, may be unable to make interest payments and/or repay principal in a timely manner.

Industry and sector risk - The risk that the value of securities in a particular industry or sector (such as banking) will decline because of changing expectations for the performance of that industry or sector.

High yield (junk) bond risk - The risk that high yield securities, commonly known as "junk bonds," are subject to reduced creditworthiness of issuers, increased risk of default, and a more limited and less liquid secondary market. High yield securities may also be subject to greater price volatility and risk of loss of income and principal than are higher-rated securities. High yield bonds are sometimes issued by municipalities that have less financial strength and therefore have less ability to make projected debt payments on the bonds.

Loans and other indebtedness risk - The risk that a fund will not receive payment of principal, interest, and other amounts due in connection with these investments and will depend primarily on the financial condition of the borrower and the lending institution. A fund's ability to sell its loans or to realize their full value upon sale may also be impaired due to the lack of an active trading market, irregular trading activity, wide bid/ask spreads, contractual restrictions, and extended trade settlement periods. In addition, certain loans in which a fund invests may not be considered securities. A fund therefore may not be able to rely upon the anti-fraud provisions of the federal securities laws with respect to these investments.

Foreign risk - The risk that foreign securities (particularly in emerging markets) may be adversely affected by political instability, changes in currency exchange rates, inefficient markets and higher transaction costs, foreign economic conditions, the imposition of economic or trade sanctions, or inadequate or different regulatory and accounting standards.

Liquidity risk - The possibility that investments cannot be readily sold within seven calendar days at approximately the price at which a fund has valued them.

Government and regulatory risk - The risk that governments or regulatory authorities may take actions that could adversely affect various sectors of the securities markets and affect fund performance.

Active management and selection risk - The risk that the securities selected by a fund's management will underperform the markets, the relevant indices, or the securities selected by other funds with similar investment objectives and investment strategies. The securities and sectors selected may vary from the securities and sectors included in the relevant index.

None of the entities noted in this document is an authorized deposit-taking institution for the purposes of the Banking Act 1959 (Commonwealth of Australia) and the obligations of these entities do not represent deposits or other liabilities of Macquarie Bank Limited ABN 46 008 583 542 (Macquarie Bank). Macquarie Bank does not guarantee or otherwise provide assurance in respect of the

obligations of these entities. In addition, if this document relates to an investment (a) each investor is subject to investment risk including possible delays in repayment and loss of income and principal invested and (b) none of Macquarie Bank or any other Macquarie Group company guarantees any particular rate of return on or the performance of the investment, nor do they guarantee repayment of capital in respect of the investment.

How has Delaware Extended Duration Bond Fund performed?

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns for the 1-, 5-, and 10-year or lifetime periods compare with those of a broad measure of market performance and an additional index with characteristics relevant to the Fund. The Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. The returns reflect any expense caps in effect during these periods. The returns would be lower without the expense caps. You may obtain the Fund's most recently available month-end performance by calling 800 523-1918 or by visiting our website at delawarefunds.com/performance.

Calendar year-by-year total return (Class A)

As of September 30, 2024, the Fund's Class A shares had a calendar year-to-date return of 4.66%. During the periods illustrated in this bar chart, Class A's highest quarterly return was 12.51% for the quarter ended December 31, 2023, and its lowest quarterly return was -13.32% for the quarter ended June 30, 2022. The maximum Class A sales charge of 4.50%, which is normally deducted when you purchase shares, is not reflected in the highest/lowest quarterly returns or in the bar chart. If this fee were included, the returns would be less than those shown. The average annual total returns in the table below do include the sales charge.

Average annual total returns for periods ended December 31, 2023

* In connection with new regulatory requirements, effective July 31, 2024, the Fund changed its broad-based securities market benchmark index from the Bloomberg Long US Corporate Index to the Bloomberg US Aggregate Bond Index. Although the Fund will continue to show the performance of the Bloomberg Long US Corporate Index for comparative purposes, the Bloomberg US Aggregate Bond Index can be considered more broadly representative of the overall securities market applicable to the Fund.

After-tax performance is presented only for Class A shares of the Fund. The after-tax returns for other Fund classes may vary. Actual after-tax returns depend on the investor's individual tax situation and may differ from the returns shown. After-tax returns are not relevant for shares held in tax-advantaged investment vehicles such as employer-sponsored 401(k) plans and individual retirement accounts (IRAs). The after-tax returns shown are calculated using the highest individual federal marginal income tax rates in effect during the periods presented and do not reflect the impact of state and local taxes.

Who manages the Fund?

Investment manager

Delaware Management Company, a series of Macquarie Investment Management Business Trust (a Delaware statutory trust)

Sub-advisors

Macquarie Investment Management Austria Kapitalanlage AG

Macquarie Investment Management Europe Limited

Macquarie Investment Management Global Limited

Purchase and redemption of Fund shares

You may purchase or redeem shares of the Fund on any day that the New York Stock Exchange (NYSE) is open for business (Business Day). Shares may be purchased or redeemed: through your financial intermediary; through the Fund's website at delawarefunds.com/account-access; by calling 800 523-1918; by regular mail (c/o Delaware Funds by Macquarie​®, P.O. Box 534437, Pittsburgh, PA 15253-4437); by overnight courier service (c/o Delaware Funds by Macquarie Service Center, Attention: 534437, 500 Ross Street, 154-0520, Pittsburgh, PA 15262); or by wire.

For Class A and Class C shares, the minimum initial investment is generally $1,000 and subsequent investments can be made for as little as $100. The minimum initial investment for IRAs, Uniform Gifts/Transfers to Minors Act accounts, direct deposit purchase plans, and automatic investment plans is $250 and through Coverdell Education Savings Accounts is $500, and subsequent investments in these accounts can be made for as little as $25. For Class R, Institutional Class, and Class R6 shares (except those shares purchased through an automatic investment plan), there is no minimum initial purchase requirement, but certain eligibility requirements must be met. The eligibility requirements are described in this Prospectus under "Choosing a share class" and on the Fund's website. We may reduce or waive the minimums or eligibility requirements in certain cases.

Please refer to the Fund's prospectus and statement of additional information for more details regarding the purchase and sale of Fund shares.

Tax information

The Fund's distributions generally are taxable to you as ordinary income, capital gains, or some combination of both, unless you are investing through a tax-advantaged arrangement, such as a 401(k) plan or an IRA, in which case your distributions may be taxed as ordinary income when withdrawn from the tax-advantaged account.

Payments to broker/dealers and other financial intermediaries

If you purchase shares of the Fund through a broker/dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker/dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary's website for more information.