497 1 ils052418pro497.txt PROSPECTUS SUPPLEMENT May 24, 2018 PIONEER ILS INTERVAL FUND SUPPLEMENT TO THE PROSPECTUS DATED MARCH 1, 2018 MANAGEMENT Effective June 8, 2018, the following replaces the corresponding information under the heading "Portfolio Managers" in the section entitled "Management of the fund": Day-to-day management of the fund's portfolio is the responsibility of Chin Liu. The portfolio manager is supported by the Adviser's fixed income team. Members of this team manage other Pioneer funds investing primarily in fixed income securities. The portfolio manager and the team also may draw upon the research and investment management expertise of the global research teams, which provide fundamental and quantitative research and include members from one or more of Amundi Pioneer's affiliates. Mr. Liu is a Senior Vice President and Director of Insurance-Linked Securities and Quantitative Research of Amundi Pioneer. He joined Amundi Pioneer in 2007 and has been an investment professional since 2005. Prior to joining Amundi Pioneer, Mr. Liu was a quantitative equity analyst for Numeric Investors and a customer investment researcher for E Trade Financial. Mr. Liu has served as a portfolio manager of the fund since 2014. 31037-00-0518 (Copyright)2018 Amundi Pioneer Distributor, Inc. Underwriter of Pioneer mutual funds Member SIPC