Summary Prospectus by Investment Company - Form 497K

Fixed income mutual fund

Delaware Investments Ultrashort Fund

July 31, 2024

(to be renamed Macquarie Ultrashort Fund on or about December 31, 2024)

What is the Fund's investment objective?

Delaware Investments Ultrashort Fund seeks total return to the extent consistent with a relatively low volatility of principal.

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.

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. 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 81% of the average value of its portfolio.

What are the Fund's principal investment strategies?

Under normal circumstances, the Fund will invest all of its net assets, plus the amount of any borrowings for investment purposes, in investment grade fixed income securities at the time of purchase, including, but not limited to, fixed income securities issued or guaranteed by the US government, its agencies or instrumentalities, and by US and non-US corporations. Investment grade fixed income securities are securities rated BBB- or higher by Standard & Poor's Financial Services LLC (S&P) or Baa3 or higher by Moody's Investors Service, Inc. (Moody's), or similarly rated by another nationally recognized statistical rating organization (NRSRO), or those that are deemed to be of comparable quality. The Fund will maintain an average effective duration of less than 18 months. 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.

The Fund's investment manager, Delaware Management Company (Manager), will determine how much of the Fund's assets to allocate among the different types of fixed income securities in which the Fund may invest based on the Manager's evaluation of economic and market conditions and the Manager's assessment of the returns and potential for appreciation that can be achieved from various sectors of the fixed income market. 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 the 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 corporate debt obligations in which the Fund may invest include bonds, notes, debentures, and commercial paper of US companies and non-US companies. The Fund may also invest in a variety of securities that are issued or guaranteed as to the payment of principal and interest by the US government, and by various agencies or instrumentalities, which have been established or are sponsored by the US government, and securities issued by foreign governments.

Additionally, the Fund may invest in mortgage-backed securities issued or guaranteed by the US government, its agencies or instrumentalities, or government-sponsored corporations, and mortgage-backed securities issued by certain private, nongovernment entities. The Fund may also invest in securities that are backed by assets such as receivables on home equity and credit card loans, automobile, mobile home, recreational vehicle and other loans, wholesale dealer floor plans, and leases.

The Fund may invest up to 30% of its net assets in foreign securities, including up to 10% of its net assets in securities of issuers located in emerging markets.

The Fund may use a wide range of derivatives instruments, typically including options, futures contracts, options on futures contracts, forward foreign currency contracts, credit default swaps, interest rate swaps, and index swaps. The Fund will use derivatives for both hedging and nonhedging purposes. For example, the Fund may invest in: futures and options to manage duration and for defensive purposes, such as to protect gains or hedge against potential losses in the portfolio without actually selling a security, or to stay fully invested; forward foreign currency contracts to manage foreign currency exposure; interest rate swaps to neutralize the impact of interest rate changes; credit default swaps to hedge against bond defaults, to manage credit exposure, or to enhance total return; and index swaps to enhance return or to effect diversification. The Fund will not use derivatives for reasons inconsistent with its investment objective and will limit its investments in derivatives instruments to 10% of its net assets.

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.

Foreign and emerging markets risk - The risk that international investing (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. The risk associated with international investing will be greater in emerging markets than in more developed foreign markets because, among other things, emerging markets may have less stable political and economic environments. In addition, there often is substantially less publicly available information about issuers and such information tends to be of a lesser quality. Economic markets and structures tend to be less mature and diverse and the securities markets may also be smaller, less liquid, and subject to greater price volatility.

Inflation risk - The risk that the return from your investments will be less than the increase in the cost of living due to inflation.

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.

Derivatives risk - Derivatives contracts, such as futures, forward foreign currency contracts, options, and swaps, may involve additional expenses (such as the payment of premiums) and are subject to significant loss if a security, index, reference rate, or other asset or market factor to which a derivatives contract is associated, moves in the opposite direction from what the Manager anticipated. When used for hedging, the change in value of the derivatives instrument may also not correlate specifically with the currency, rate, or other risk being hedged, in which case a fund may not realize the intended benefits. Derivatives contracts are also subject to the risk that the counterparty may fail to perform its obligations under the contract due to, among other reasons, financial difficulties (such as a bankruptcy or reorganization).

Leveraging risk - The risk that certain fund transactions, such as reverse repurchase agreements, short sales, loans of fund securities, and the use ofwhen-issued, delayed delivery or forward commitment transactions, or derivatives instruments, may give rise to leverage, causing a fund to be more volatile than if it had not been leveraged, which may result in increased losses to the fund.

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.

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.

Mortgage-backed and asset-backed securities risk - Mortgage-backed and asset-backed securities, like other fixed income securities, are subject to credit risk and interest rate risk, and may also be subject to prepayment risk and extension risk. Prepayment risk is the risk that the principal on mortgage-backed or asset-backed securities may be prepaid at any time, which will reduce the yield and market value of the securities and may cause the fund to reinvest the proceeds in lower yielding securities. Extension risk is the risk that principal on mortgage-backed or asset-backed securities will be repaid more slowly than expected, which may reduce the proceeds available for reinvestment in higher yielding securities. In addition, mortgage-backed and asset-backed securities may decline in value, become more volatile, face difficulties in valuation, or experience reduced liquidity due to changes in interest rates or general economic conditions. Certain mortgage-backed or asset-backed securities, such as collateralized mortgage obligations, real estate mortgage investment conduits, and stripped mortgage-backed securities, may be more susceptible to these risks than other mortgage-backed, asset-backed, or fixed-income securities.

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.

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 Investments Ultrashort 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-year, 5-year, and 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 (Institutional Class)

As of June 30, 2024, the Fund's Institutional Class shares had a calendar year-to-date return of 2.55%. During the periods illustrated in this bar chart, Institutional Class's highest quarterly return was 2.85% for the quarter ended June 30, 2020, and its lowest quarterly return was -2.53% for the quarter ended March 31, 2020.

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 ICE BofA 6-Month Treasury Bill Index to the Bloomberg U.S. Aggregate Bond Index. Although the Fund will continue to show the performance of the ICE BofA 6-Month Treasury Bill Index for comparative purposes, the Bloomberg U.S. Aggregate Bond Index can be considered more broadly representative of the overall securities market applicable to the Fund.

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.

The Fund offers only Institutional Class shares. There are no minimum initial purchase or eligibility requirements to purchase Institutional Class shares of the Fund.

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.