PIMCO Funds Supplement dated August 30, 2021 to the Asset Allocation Funds Prospectus, Bond Funds Prospectus, Credit Bond Funds Prospectus, Equity-Related Strategy Funds Prospectus, International Bond Funds Prospectus, Municipal Value Funds Prospectus, Real Return Strategy Funds Prospectus and Tax-Efficient Strategy Funds Prospectus, each dated July 30, 2021, as supplemented from time to time (the “Prospectuses”) and the PIMCO All Asset All Authority Fund, PIMCO All Asset Fund, PIMCO California Intermediate Municipal Bond Fund, PIMCO California Municipal Bond Fund, PIMCO California Short Duration Municipal Income Fund, PIMCO Climate Bond Fund, PIMCO Diversified Income Fund, PIMCO Global Advantage® Strategy Bond Fund, PIMCO Global Bond Opportunities Fund (U.S. Dollar-Hedged), PIMCO Global Bond Opportunities Fund (Unhedged), PIMCO Global Core Asset Allocation Fund, PIMCO GNMA and Government Securities Fund, PIMCO Municipal Bond Fund, PIMCO High Yield Municipal Bond Fund, PIMCO Income Fund, PIMCO Inflation Response Multi-Asset Fund, PIMCO International Bond Fund (U.S. Dollar-Hedged), PIMCO International Bond Fund (Unhedged), PIMCO Investment Grade Credit Bond Fund, PIMCO Long Duration Total Return Fund, PIMCO Long-Term Credit Bond Fund, PIMCO Long-Term Real Return Fund, PIMCO Long-Term U.S. Government Fund, PIMCO Low Duration Income Fund, PIMCO Moderate Duration Fund, PIMCO Mortgage-Backed Securities Fund, PIMCO New York Municipal Bond Fund, PIMCO Real Return Fund, PIMCO Short Duration Municipal Income Fund, PIMCO StocksPLUS® Long Duration Fund, PIMCO Total Return Fund, PIMCO Total Return Fund II, PIMCO Total Return Fund IV and PIMCO Total Return ESG Fund Summary Prospectuses, each dated July 30, 2021, each as supplemented from time to time (the “Summary Prospectuses) The Bloomberg Barclays fixed income indices have been renamed in connection with the rebranding of the indices as the “Bloomberg Fixed Income Indices.” In addition, the Bloomberg Barclays MSCI indices have been renamed in connection with the rebranding of the indices as the “Bloomberg MSCI ESG Fixed Income Indices.” Accordingly, effective immediately, all references in the Prospectuses and Summary Prospectuses to the indexes listed in the “Previous Index Name” column below are hereby removed and replaced with the indexes listed in the “New Index Name” column below. Previous Index Name New Index Name Bloomberg Barclays MSCI Green Bond Index Bloomberg MSCI Green Bond Index Bloomberg Barclays GNMA Index Bloomberg GNMA Index Bloomberg Barclays U.S. Credit Index Bloomberg U.S. Credit Index Bloomberg Barclays Long-Term Government/Credit Bloomberg Long-Term Government/Credit Index Index Bloomberg Barclays Long-Term Treasury Index Bloomberg Long-Term Treasury Index Bloomberg Barclays Intermediate Government/ Bloomberg Intermediate Government/Credit Index Credit Index Bloomberg Barclays U.S. MBS Fixed Rate Index Bloomberg U.S. MBS Fixed Rate Index Bloomberg Barclays U.S. Aggregate Index Bloomberg U.S. Aggregate Index Bloomberg Barclays U.S. Aggregate 1-3 Years Index Bloomberg U.S. Aggregate 1-3 Years Index Bloomberg Barclays Global Aggregate (USD Bloomberg Global Aggregate (USD Unhedged) Unhedged) Index Index Bloomberg Barclays Global Aggregate (USD Bloomberg Global Aggregate (USD Hedged) Index Hedged) Index Bloomberg Barclays California 1-10 Year (1-12) Bloomberg California 1-10 Year (1-12) Municipal Municipal Securities Index Securities Index Bloomberg Barclays U.S. TIPS Index Bloomberg U.S. TIPS Index Previous Index Name New Index Name Bloomberg Barclays U.S. TIPS: 1-10 Year Index Bloomberg U.S. TIPS: 1-10 Year Index Bloomberg Barclays Global Credit Hedged USD Bloomberg Global Credit Hedged USD Index Index Bloomberg Barclays Global Aggregate Credit ex Bloomberg Global Aggregate Credit ex Emerging Emerging Markets (USD Hedged) Index Markets (USD Hedged) Index Bloomberg Barclays Global Aggregate ex-USD Bloomberg Global Aggregate ex-USD (USD (USD Unhedged) Index Unhedged) Index Bloomberg Barclays Global Aggregate ex-USD Bloomberg Global Aggregate ex-USD (USD (USD Hedged) Index Hedged) Index Bloomberg Barclays High Yield Municipal Bond Bloomberg High Yield Municipal Bond Index Index Bloomberg Barclays California Municipal Bond Bloomberg California Municipal Bond Index Index Bloomberg Barclays California Intermediate Bloomberg California Intermediate Municipal Bond Municipal Bond Index Index Bloomberg Barclays California 1 Year Municipal Bloomberg California 1 Year Municipal Bond Index Bond Index Bloomberg Barclays 1 Year Municipal Bond Index Bloomberg 1 Year Municipal Bond Index Bloomberg Barclays Municipal Bond 1-10 Year Bloomberg Municipal Bond 1-10 Year Blend (1-12) Blend (1-12) Index Index Bloomberg Barclays Municipal Bond Index Bloomberg Municipal Bond Index Bloomberg Barclays 1-15 Year Municipal Bond Bloomberg 1-15 Year Municipal Bond Index Index Bloomberg Barclays New York Municipal Bond Bloomberg New York Municipal Bond Index Index Bloomberg Barclays U.S. Long Credit Index Bloomberg U.S. Long Credit Index Bloomberg Barclays U.S. Treasury Inflation Notes: Bloomberg U.S. Treasury Inflation Notes: 10+ Years 10+ Years Index Index Investors Should Retain This Supplement for Future Reference PIMCO_SUPP3_083021 PIMCO Funds Supplement Dated July 30, 2021 to the Bond Funds Prospectus (the “Prospectus”) dated July 30, 2021, as supplemented from time to time Disclosure Related to the PIMCO Dynamic Bond Fund (the “Fund”) As previously disclosed in a supplement dated February 4, 2021 to the Prospectus dated July 31, 2020, as supplemented from time to time, Pacific Investment Management Company LLC (“PIMCO”) has announced that Mohsen Fahmi will retire from PIMCO effective December 31, 2021. Mr. Fahmi will continue to serve as a portfolio manager of the Fund until December 31, 2021 or such earlier date to be disclosed in a subsequent supplement. Investors Should Retain This Supplement for Future Reference PIMCO_SUPP2_073021 PIMCO Funds Prospectus July 30, 2021 Bond Funds Inst I-2 I-3 Admin A C R PIMCO Climate Bond Fund PCEIX PCEPX PCEWX – PCEBX PCECX – PIMCO Dynamic Bond Fund PFIUX PUCPX PFNUX – PUBAX PUBCX PUBRX PIMCO Extended Duration Fund PEDIX PEDPX – – – – – PIMCO GNMA and Government PDMIX PPGNX PANNX PAGNX PCGNX – – Securities Fund PIMCO Investment Grade Credit Bond PIGIX PBDPX PCNNX PGCAX PBDAX PBDCX – Fund PIMCO Long Duration Total Return PLRIX PLRPX PLRAX PLRCX – – – Fund PIMCO Long-Term U.S. Government PGOVX PLTPX PLGBX PFGAX PFGCX – – Fund PIMCO Moderate Duration Fund PMDRX PMOPX – – – – – PIMCO Mortgage-Backed Securities PTRIX PMRPX PSANX PMRAX PMRCX – – Fund PIMCO Mortgage Opportunities and PMZIX PMZPX PMZNX PMZAX PMZCX – – Bond Fund PIMCO Strategic Bond Fund PUTIX PUTPX – – ATMAX ATMCX – PIMCO Total Return Fund PTTRX PTTPX PTTNX PTRAX PTTAX PTTCX PTRRX PIMCO Total Return Fund II PMBIX PMTPX – PRADX – – – PIMCO Total Return Fund IV PTUIX – – – PTUZX – – PIMCO Total Return ESG Fund PTSAX PRAPX – PRFAX PTGAX PTGCX – As with other mutuaI funds, neither the U.S. Securities and Exchange Commission nor the U.S. Commodity Futures Trading Commission has approved or disapproved these securities, or determined if this prospectus is truthfuI or compIete. Any representation to the contrary is a criminaI offense. As permitted by reguIations adopted by the Securities and Exchange Commission, paper copies of the Fund's annuaI and semi-annuaI sharehoIder reports wiII no Ionger be sent by maiI, unIess you specificaIIy request paper copies of the reports from the Fund or from your financiaI intermediary, such as a broker-deaIer or bank. Instead, the reports wiII be made avaiIabIe on the Fund's website, pimco.com/Iiterature, and you wiII be notified by maiI each time a report is posted and provided with a website Iink to access the report. If you aIready eIected to receive sharehoIder reports eIectronicaIIy, you wiII not be affected by this change and you need not take any action. You may eIect to receive sharehoIder reports and other communications from the Fund eIectronicaIIy by visiting pimco.com/edeIivery or by contacting your financiaI intermediary, such as a broker-deaIer or bank. You may eIect to receive aII future reports in paper free of charge. If you own these shares through a financiaI intermediary, such as a broker-deaIer or bank, you may contact your financiaI intermediary to request that you continue to receive paper copies of your sharehoIder reports. If you invest directIy with the Fund, you can inform the Fund that you wish to continue receiving paper copies of your sharehoIder reports by caIIing 888.87.PIMCO (888.877.4626). Your eIection to receive reports in paper wiII appIy to aII funds heId with the fund compIex if you invest directIy with the Fund or to aII funds heId in your account if you invest through a financiaI intermediary, such as a broker-deaIer or bank. Table of Contents Page Fund Summaries 1 PIMCO Climate Bond Fund 1 PIMCO Dynamic Bond Fund 6 PIMCO Extended Duration Fund 10 PIMCO GNMA and Government Securities Fund 14 PIMCO Investment Grade Credit Bond Fund 18 PIMCO Long Duration Total Return Fund 22 PIMCO Long-Term U.S. Government Fund 26 PIMCO Moderate Duration Fund 30 PIMCO Mortgage-Backed Securities Fund 34 PIMCO Mortgage Opportunities and Bond Fund 38 PIMCO Strategic Bond Fund 42 PIMCO Total Return Fund 46 PIMCO Total Return Fund II 50 PIMCO Total Return Fund IV 53 PIMCO Total Return ESG Fund 57 Summary of Other Important Information Regarding Fund Shares 62 Description of Principal Risks 63 Disclosure of Portfolio Holdings 74 Management of