0001094521 2021-10-01 2021-10-01 0001094521 pioneer:S000015510Member pioneer:Cik0001380192Member 2021-10-01 2021-10-01 0001094521 pioneer:S000003948Member pioneer:Cik0000869356Member 2021-10-01 2021-10-01 0001094521 pioneer:S000031914Member pioneer:Cik0001174520Member 2021-10-01 2021-10-01 0001094521 pioneer:S000031915Member pioneer:Cik0001174520Member 2021-10-01 2021-10-01 0001094521 pioneer:S000010131Member pioneer:Cik0001077452Member 2021-10-01 2021-10-01 0001094521 pioneer:S000004009Member pioneer:Cik0001051010Member 2021-10-01 2021-10-01 0001094521 pioneer:S000010136Member pioneer:Cik0000078758Member 2021-10-01 2021-10-01 0001094521 pioneer:S000004143Member pioneer:Cik0000863334Member 2021-10-01 2021-10-01 0001094521 pioneer:S000003994Member pioneer:Cik0001094521Member 2021-10-01 2021-10-01 0001094521 pioneer:S000010121Member pioneer:Cik0001341256Member 2021-10-01 2021-10-01 0001094521 pioneer:S000004137Member pioneer:Cik0001174520Member 2021-10-01 2021-10-01 0001094521 pioneer:S000035110Member pioneer:Cik0001331854Member 2021-10-01 2021-10-01 0001094521 pioneer:S000010203Member pioneer:Cik0001140157Member 2021-10-01 2021-10-01 0001094521 pioneer:S000010084Member pioneer:Cik0001265389Member 2021-10-01 2021-10-01 0001094521 pioneer:S000010228Member pioneer:Cik0001286364Member 2021-10-01 2021-10-01 0001094521 pioneer:S000004011Member pioneer:Cik0000893660Member 2021-10-01 2021-10-01 0001094521 pioneer:S000028857Member pioneer:Cik0001380192Member 2021-10-01 2021-10-01 0001094521 pioneer:S000010093Member pioneer:Cik0001306349Member 2021-10-01 2021-10-01 0001094521 pioneer:S000065786Member pioneer:Cik0001077452Member 2021-10-01 2021-10-01 0001094521 pioneer:S000071520Member pioneer:Cik0001077452Member 2021-10-01 2021-10-01 0001094521 pioneer:S000003927Member pioneer:Cik0000276776Member 2021-10-01 2021-10-01 pure iso4217:USD 2021-10-01 PIONEER HIGH YIELD FUND 0001094521 false 2021-10-01 2021-10-01 2021-10-01 N-1A 497 October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC October 1, 2021Pioneer FundsSupplement to the Prospectus and Summary Prospectus, as in effect and as may be amended from time to time, for:FundDate of ProspectusPioneer Strategic Income FundFebruary 1, 2021Pioneer Emerging Markets Equity FundFebruary 1, 2021Pioneer Equity Income FundMarch 1, 2021Pioneer Flexible Opportunities FundMarch 1, 2021Pioneer Floating Rate FundMarch 1, 2021Pioneer Global High Yield FundMarch 1, 2021Pioneer High Yield FundMarch 1, 2021Pioneer Mid Cap Value FundMarch 1, 2021Pioneer International Equity FundApril 1, 2021Pioneer Select Mid Cap Growth FundApril 1, 2021Pioneer Core Equity FundMay 1, 2021Pioneer Intrinsic Value FundMay 7, 2021Pioneer Multi-Asset Ultrashort Income FundAugust 1, 2021Pioneer Fundamental Growth FundAugust 1, 2021Pioneer Bond FundNovember 1, 2020Pioneer Multi-Asset Income FundDecember 1, 2020Pioneer Disciplined Growth FundDecember 31, 2020Pioneer Disciplined Value FundDecember 31, 2020Pioneer Global Equity FundDecember 31, 2020Pioneer Corporate High Yield FundDecember 31, 2020Pioneer Short Term Income FundDecember 31, 2020The following supplements information in the sections entitled “Fund summary - Principal investment strategies” and “More on the fund’s investment objective(s) and strategies - Principal investment strategies” in the Prospectus and “Principal investment strategies” in the Summary Prospectus.ESG considerationsThe adviser integrates environmental, social and corporate governance (ESG) considerations into its investment research process by evaluating the business models and practices of issuers and their ESG-related risks. The adviser believes ESG analysis is a meaningful facet of fundamental research, the process of evaluating an issuer based on its financial position, business operations, competitive standing and management. This process considers ESG information, where available, in assessing an investment’s performance potential. The adviser generally considers ESG information in the context of an issuer’s respective sector or industry. The adviser may consider ESG ratings provided by third parties or internal sources, as well as issuer disclosures and public information, in evaluating issuers. ESG considerations are not a primary focus of the fund, and the weight given by the adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight.32671-00-1021 ©2021 Amundi Distributor US, Inc. Underwriter of Pioneer mutual funds Member SIPC