OPTIMUM FUND TRUST

Optimum Fixed Income Fund (the “Fund”)

Supplement to the Fund’s Prospectus dated July 29, 2020

Effective September 30, 2020, the following replaces the information in the section entitled “Fund summaries — Optimum Fixed Income Fund — Who manages the Fund? — Investment manager”:

Investment manager

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

Effective September 30, 2020, the following replaces the biographical information in the section entitled “Who manages the Funds — Sub-advisors and portfolio managers — Optimum Fixed Income Fund”:

J. David Hillmeyer and Daniela Mardarovici are primarily responsible for the day-to-day management of the Manager's share of the Fund's assets.  When making decisions for the Fund, Mr. Hillmeyer and Ms. Mardarovici regularly consult with other investment professionals.

Mr. Hillmeyer co-leads of the firm’s US Multisector Fixed Income team for Macquarie Investment Management Fixed Income (MFI) with responsibility for investment strategy and business development across the full suite of US multisector strategies. In addition, Hillmeyer has responsibility for our global credit strategies. Mr. Hillmeyer is also a member of MFI’s Global Leadership Group which is responsible for the overall management of MFI including setting and executing on the team’s strategic vision. Prior to joining Macquarie Investment Management (MIM) in August 2007 as a vice president and corporate bond trader, he worked for more than 11 years in various roles at Hartford Investment Management Company, including senior corporate bond trader, high yield portfolio manager / trader, and quantitative analyst. He began his career as an investment advisor in January 1989 at Shawmut Bank, leaving the firm as an investment officer in November 1995. Hillmeyer earned his bachelor’s degree from Colorado State University, and he is a member of the CFA Society of Philadelphia and the Philadelphia Council for Business Economics. Mr. Hillmeyer assumed Fund responsibilities in April 2011.

Ms. Mardarovici co-leads of the firm’s US Multisector Fixed Income team for Macquarie Investment Management Fixed Income (MFI) with responsibility for investment strategy and business development across the full suite of US multisector strategies. Mardarovici is also a member of MFI’s Global Leadership Group which is responsible for the overall management of MFI including setting and executing on the team’s strategic vision. Prior to joining Macquarie Investment Management (MIM) in March 2019, she spent more than 13 years at BMO Global Asset Management as a senior portfolio manager. Since 2014, she was a member of the management committee of Taplin, Canida & Habacht (TCH), BMO’s US fixed income group, and helped lead business strategy and development efforts. Mardarovici was also responsible for driving investment strategy and managing institutional portfolios and mutual funds across a wide spectrum of strategies, including core, core plus, credit, multisector, and liability-driven investing (LDI). Previously, she led investment management efforts for mortgage-backed securities at Harris

Investment Management. She started her career in 2000 as a proprietary trader at Gelber Group. In 2018, Mardarovici was named one of the top 20 female portfolio managers by CityWire. She graduated magna cum laude with a major in economics and finance/banking from the University of Nebraska at Omaha. She is a member of the CFA Society New York and the CFA Institute. Ms. Mardarovici assumed Fund responsibilities in March 2019.

Pacific Investment Management Company LLC (PIMCO), located at 650 Newport Center Drive, Newport Beach, CA 92660, was founded in 1971. As of March 31, 2020, PIMCO manages $1.78 trillion in assets, including $1.37 trillion in third-party client assets. Assets include $15.3 billion in assets of clients contracted with Gurtin Fixed Income Management, LLC, an affiliate and wholly-owned subsidiary of PIMCO. PIMCO has held its Fund responsibilities since April 2010.

Marc P. Seidner is primarily responsible for the day-to-day management of PIMCO's share of the Fund's assets.

Mr. Seidner is CIO Non-traditional Strategies, a managing director and head of portfolio management in the New York office. He is also a generalist portfolio manager and a member of the Investment Committee. He rejoined PIMCO in November 2014 after serving as head of fixed income at GMO LLC, and previously he was a PIMCO managing director, generalist portfolio manager and member of the Investment Committee until January 2014. Prior to joining PIMCO in 2009, he was a managing director and domestic fixed income portfolio manager at Harvard Management Company. Previously, he was director of active core strategies at Standish Mellon Asset Management and a senior portfolio manager at Fidelity Management and Research. He has 33 years of investment experience and holds an undergraduate degree in economics from Boston College. He has held his Fund responsibilities since January 2015.

In addition, PIMCO has an Investment Committee, which oversees the setting of investment policy decisions, including duration positioning, yield curve management, sector rotation, credit quality and overall portfolio composition, for all PIMCO portfolios and strategies, including PIMCO's share of the Fund's assets.

Macquarie Investment Management Austria Kapitalanlage AG (MIMAK), located at Kaerntner Strasse 28, 1010 Vienna, Austria, is an affiliate of the Manager and a part of Macquarie Investment Management (MIM). MIM is the marketing name for certain companies comprising the asset management division of Macquarie Group Limited. As of June 30, 2020, MIM managed more than $250.0 billion in assets for institutional and individual clients. Although the Manager has principal responsibility for the Manager’s portion of the Fund, the Manager may seek investment advice and recommendations from MIMAK and the Manager may also permit MIMAK 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 MIMAK’s specialized market knowledge.

Macquarie Investment Management Europe Limited, (MIMEL), located at 28 Ropemaker Street, London, England, is an affiliate of the Manager and a part of MIM. Although the Manager has principal responsibility for the Manager’s portion of the Fund, the Manager may seek investment advice and recommendations from MIMEL and the Manager may also permit MIMEL 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 MIMEL’s specialized market knowledge.

Macquarie Investment Management Global Limited, (MIMGL), located at 50 Martin Place, Sydney, Australia, is an affiliate of the Manager and a part of MIM. Although the Manager has principal responsibility for the Manager’s portion of the Fund, the Manager may seek investment advice and recommendations from MIMGL and the Manager may also permit MIMGL 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 MIMGL’s specialized market knowledge.

The SAI provides additional information about each portfolio manager’s compensation, other accounts managed by each portfolio manager, and each portfolio manager’s ownership of Fund shares.

Because everyone’s tax situation is unique, you should consult your tax professional about federal, state, local, or foreign tax consequences before making an investment in the Fund.

Delaware Management Company (Manager) is an indirect wholly owned subsidiary of Macquarie Group Limited (MGL). Other than Macquarie Bank Limited (MBL), a subsidiary of MGL and an affiliate of the Manager, none of the entities noted are authorized deposit-taking institutions for the purposes of the Banking Act 1959 (Commonwealth of Australia). The obligations of these entities do not represent deposits or other liabilities of MBL. MBL does not guarantee or otherwise provide assurance in respect of the obligations of these entities, unless noted otherwise. The Fund is governed by US laws and regulations.

Please keep this Supplement for future reference.

This Supplement is dated August 26, 2020.