Form POS AMI PIMCO FUNDS

PIMCO Funds

Private Account Portfolio Series

Amendment Dated November 20, 2025 to the PIMCO All Asset Funds Offering Memorandum

dated August 1, 2025, as amended from time to time (the “Offering Memorandum”)

Disclosure Regarding PIMCO All Asset: Multi-RAE PLUS Fund and PIMCO All Authority: Multi-RAE PLUS Fund (each, a “Fund” and together, the “Funds”)

Effective December 22, 2025, the “Principal Investment Strategies” section of each Fund’s Fund Summary in the Offering Memorandum is deleted in its entirety and replaced with the following:

PIMCO All Asset: Multi-RAE PLUS Fund

The Fund seeks to achieve its investment objective by obtaining exposures to a portfolio of stocks and complementing these equity exposures with an absolute return bond alpha strategy (“AR Bond Alpha Strategy”). In addition to long equity exposures, the Fund may also obtain short exposure to equity markets, but will not normally seek to obtain a net short equity exposure.

In managing the Fund’s equity exposures, PIMCO utilizes an approach that is designed to have flexibility with respect to different equity markets, segments and issuers, such as global regions and countries, sectors and market capitalizations. The Fund expects to use long exposure and short exposure in addition to or in place of investments in stocks and/or equity-related underlying funds (such as exchange-traded funds) to obtain exposure to a portfolio of stocks. The Fund may seek equity exposure through any of the foregoing instruments, without limitation, in PIMCO’s and Research Affiliates’ (“Sub-Adviser’s”) discretion, as applicable. The Sub-Adviser will determine the target mix of long and short equity exposures for the Fund. In doing so, the Sub-Adviser considers a broad range of quantitative data and qualitative inputs, both in isolation and to a material degree as inputs into a series of quantitative models that inform the final allocation and trading decisions, which are made by the Fund’s portfolio managers. The quantitative data and qualitative inputs considered include (but are not limited to) macroeconomic data relating to U.S. and foreign economies (such as economic growth measures, inflation measures, production and consumption measures, trade figures, fiscal policies and monetary policies) and financial market data relating to U.S. and foreign asset classes (such as yield levels, income growth rates, valuation measures, credit and default risk measures and financial statement data). These data points are primarily used as inputs to a series of quantitative models, which collectively enable the Sub-Adviser to construct multiple optimized model portfolios for consideration in determining the Fund’s actual allocation and trading approach. These include models relating to capital markets expectations, macroeconomic regimes, risk regimes and portfolio construction. Multiple model portfolios are constructed, each optimized to different return and risk parameters, so that the portfolio managers can assess the implications, attributes and tradeoffs of different asset allocation approaches in determining the final allocation and trading decisions, in seeking to achieve the objectives of the Fund. In addition to these quantitative and model-driven considerations, which comprise a majority of the asset allocation investment process, the portfolio managers also may consider various qualitative inputs in refining their final allocation and trading decisions. These may include qualitative macroeconomic and financial market views held by the Sub-Adviser and PIMCO, as well as subjective assessments of liquidity risk, risk premia attractiveness, expected net flows into the Fund and investor behavioral factors.

The Fund may use derivatives (such as, but not limited to, futures contracts, swap agreements or options) to obtain its equity exposures. The Sub-Adviser provides investment advisory services in connection with the Fund’s equity exposure by, among other things, providing PIMCO, or counterparties designated by PIMCO, with the designated equity exposure for purposes of developing certain derivatives positions. For example, the Sub-Adviser may assist in the development of equity total return swaps for the Fund. In a typical swap agreement, the Fund will receive the total return of the desired equity exposure from the counterparty to the swap agreement in exchange for paying the counterparty an agreed upon short-term interest rate. There may be a limited number of counterparties willing or able to serve as counterparties to a swap agreement. The Fund may invest in other instruments, “baskets” of stocks, or individual securities to replicate the performance of the desired equity portfolio.

In managing the Fund’s investments in the AR Bond Alpha Strategy, PIMCO seeks to enhance the Fund’s total return. The AR Bond Alpha Strategy invests in a diversified portfolio of Fixed Income Instruments and related derivatives, which may include forwards or derivatives such as options, futures contracts or swap agreements. “Fixed Income Instruments” include bonds, debt securities and other similar instruments issued by various U.S. and non-U.S. public or private-sector entities. The AR Bond Alpha Strategy is not designed to systematically provide bond market exposure, although the returns may (or may not) be positively correlated with the returns of the bond market. The AR Bond Alpha Strategy seeks to maintain an overall portfolio duration which normally varies from (negative) 3 years to positive 8 years based on PIMCO’s market forecasts among other factors. Duration is a measure used to determine the sensitivity of a security’s price to changes in interest rates. The longer a security’s duration, the more sensitive it will be to changes in interest rates. In addition to duration, the AR Bond Alpha Strategy has flexibility with respect to overall sector exposures, non-U.S. exposures and credit quality, both as a function of the strategy’s investment guidelines and lack of a bond market index benchmark. Further, PIMCO, in its discretion, may seek to reduce the overall risk in the Fund’s portfolio of Fixed Income Instruments when the Fund’s short equity positions have generated or generate higher levels of income.

In selecting investments for the Fund, PIMCO and the Sub-Adviser, as applicable, may use proprietary quantitative models that are developed and maintained by PIMCO or the Sub-Adviser, as applicable, and which are subject to change over time without notice in PIMCO’s or the Sub-Adviser’s discretion, as applicable.

The Fund may invest, without limitation, in common stocks (including any equity-related underlying funds) and derivative instruments, such as options, futures contracts or swap agreements, or in mortgage- or asset backed securities subject to applicable law and any other restrictions described in the Fund’s Offering Memorandum or Offering Memorandum Supplement. The Fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis and may engage in short sales. The Fund may also engage in financing transactions, such as reverse repurchase agreements and/or total return swaps. The Fund may invest up to 20% of its total assets in high yield securities (“junk bonds”) rated B or higher by Moody’s Ratings (“Moody’s”), Standard & Poor’s Ratings Services (“S&P”) or Fitch Ratings, Inc. (“Fitch”), or, if unrated, as determined by PIMCO (except that within such 20% limitation, the Fund may invest in mortgage- and asset-backed securities rated below B). In the event that ratings services assign different ratings to the same security, PIMCO will use the highest rating as the credit rating for that security.

The Fund may also invest, without limitation, in securities denominated in foreign currencies and in U.S. dollar-denominated securities of foreign issuers. With respect to the AR Bond Alpha Strategy, the Fund may invest up to 25% of its total assets in securities and instruments that are economically tied to emerging market countries (this limitation does not apply to investment grade sovereign debt denominated in the local currency with less than 1 year remaining to maturity, which means the Fund may invest in such instruments without limitation subject to any applicable legal or regulatory limitation). With respect to the Fund’s fixed income investments, the Fund will normally limit its net foreign currency exposure (from non-U.S. dollar-denominated securities or currencies) to 35% of its total assets. With respect to the Fund’s fixed income investments, the Fund will normally limit its exposure (from non-U.S. dollar-denominated securities or currencies) to each non-U.S. currency to 10% of its total assets. The Fund will normally limit its aggregate U.S. dollar exposure from transactions or instruments that reference the relative return of a non-U.S. currency or currencies as compared to the U.S. dollar to 20% of its total assets. The Fund may also invest up to 10% of its total assets in preferred securities.

PIMCO All Authority: Multi-RAE PLUS Fund

The Fund seeks to achieve its investment objective by obtaining exposures to a portfolio of stocks and complementing these equity exposures with an absolute return bond alpha strategy (“AR Bond Alpha Strategy”). While the Fund is expected in most market environments to have a net long equity exposure, it may have a net short equity exposure under certain market conditions.

In managing the Fund’s equity exposures, PIMCO utilizes an approach that is designed to have flexibility with respect to different equity markets, segments and issuers, such as global regions and countries, sectors and

market capitalizations. The Fund expects to use long exposure and short exposure in addition to or in place of investments in stocks and/or equity-related underlying funds (such as exchange-traded funds) to obtain exposure to a portfolio of stocks. The Fund may seek equity exposure through any of the foregoing instruments, without limitation, in PIMCO’s and Research Affiliates’ (“Sub-Adviser’s”) discretion, as applicable. The Sub-Adviser will determine the target mix of long and short equity exposures for the Fund. In doing so, the Sub-Adviser considers a broad range of quantitative data and qualitative inputs, both in isolation and to a material degree as inputs into a series of quantitative models that inform the final allocation and trading decisions, which are made by the Fund’s portfolio managers. The quantitative data and qualitative inputs considered include (but are not limited to) macroeconomic data relating to U.S. and foreign economies (such as economic growth measures, inflation measures, production and consumption measures, trade figures, fiscal policies and monetary policies) and financial market data relating to U.S. and foreign asset classes (such as yield levels, income growth rates, valuation measures, credit and default risk measures and financial statement data). These data points are primarily used as inputs to a series of quantitative models, which collectively enable the Sub-Adviser to construct multiple optimized model portfolios for consideration in determining the Fund’s actual allocation and trading approach. These include models relating to capital markets expectations, macroeconomic regimes, risk regimes and portfolio construction. Multiple model portfolios are constructed, each optimized to different return and risk parameters, so that the portfolio managers can assess the implications, attributes and tradeoffs of different asset allocation approaches in determining the final allocation and trading decisions, in seeking to achieve the objectives of the Fund. In addition to these quantitative and model-driven considerations, which comprise a majority of the asset allocation investment process, the portfolio managers also may consider various qualitative inputs in refining their final allocation and trading decisions. These may include qualitative macroeconomic and financial market views held by the Sub-Adviser and PIMCO, as well as subjective assessments of liquidity risk, risk premia attractiveness, expected net flows into the Fund and investor behavioral factors.

The Fund may use derivatives (such as, but not limited to, futures contracts, swap agreements or options) to obtain its equity exposures. The Sub-Adviser provides investment advisory services in connection with the Fund’s equity exposure by, among other things, providing PIMCO, or counterparties designated by PIMCO, with the designated equity exposure for purposes of developing certain derivatives positions. For example, the Sub-Adviser may assist in the development of equity total return swaps for the Fund. In a typical swap agreement, the Fund will receive the total return of the desired equity exposure from the counterparty to the swap agreement in exchange for paying the counterparty an agreed upon short-term interest rate. There may be a limited number of counterparties willing or able to serve as counterparties to a swap agreement. The Fund may invest in other instruments, “baskets” of stocks, or individual securities to replicate the performance of the desired equity portfolio.

In managing the Fund’s investments in the AR Bond Alpha Strategy, PIMCO seeks to enhance the Fund’s total return. The AR Bond Alpha Strategy invests in a diversified portfolio of Fixed Income Instruments and related derivatives, which may include forwards or derivatives such as options, futures contracts or swap agreements. “Fixed Income Instruments” include bonds, debt securities and other similar instruments issued by various U.S. and non-U.S. public or private-sector entities. The AR Bond Alpha Strategy is not designed to systematically provide bond market exposure, although the returns may (or may not) be positively correlated with the returns of the bond market. The AR Bond Alpha Strategy seeks to maintain an overall portfolio duration which normally varies from (negative) 3 years to positive 8 years based on PIMCO’s market forecasts among other factors. Duration is a measure used to determine the sensitivity of a security’s price to changes in interest rates. The longer a security’s duration, the more sensitive it will be to changes in interest rates. In addition to duration, the AR Bond Alpha Strategy has flexibility with respect to overall sector exposures, non-U.S. exposures and credit quality, both as a function of the strategy’s investment guidelines and lack of a bond market index benchmark. Further, PIMCO, in its discretion, may seek to reduce the overall risk in the Fund’s portfolio of Fixed Income Instruments when the Fund’s short equity positions have generated or generate higher levels of income.

In selecting investments for the Fund, PIMCO and the Sub-Adviser, as applicable, may use proprietary quantitative models that are developed and maintained by PIMCO or the Sub-Adviser, as applicable, and which are subject to change over time without notice in PIMCO’s or the Sub-Adviser’s discretion, as applicable.

The Fund may invest, without limitation, in common stocks (including any equity-related underlying funds) and derivative instruments, such as options, futures contracts or swap agreements, or in mortgage- or asset backed securities subject to applicable law and any other restrictions described in the Fund’s Offering Memorandum or Offering Memorandum Supplement. The Fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis and may engage in short sales. The Fund may also engage in financing transactions, such as reverse repurchase agreements and/or total return swaps. The Fund may invest up to 20% of its total assets in high yield securities (“junk bonds”) rated B or higher by Moody’s Ratings (“Moody’s”), Standard & Poor’s Ratings Services (“S&P”) or Fitch Ratings, Inc. (“Fitch”), or, if unrated, as determined by PIMCO (except that within such 20% limitation, the Fund may invest in mortgage- and asset-backed securities rated below B). In the event that ratings services assign different ratings to the same security, PIMCO will use the highest rating as the credit rating for that security. The Fund is non-diversified, which means that it may invest its assets in a smaller number of issuers than a diversified fund.

The Fund may also invest, without limitation, in securities denominated in foreign currencies and in U.S. dollar-denominated securities of foreign issuers. With respect to the AR Bond Alpha Strategy, the Fund may invest up to 25% of its total assets in securities and instruments that are economically tied to emerging market countries (this limitation does not apply to investment grade sovereign debt denominated in the local currency with less than 1 year remaining to maturity, which means the Fund may invest in such instruments without limitation subject to any applicable legal or regulatory limitation). With respect to the AR Bond Alpha Strategy, the Fund will normally limit its net foreign currency exposure (from non-U.S. dollar-denominated securities or currencies) to 35% of its total assets. With respect to the AR Bond Alpha Strategy, the Fund will normally limit its exposure (from non-U.S. dollar-denominated securities or currencies) to each non-U.S. currency to 10% of its total assets. With respect to the AR Bond Alpha Strategy, the Fund will normally limit its aggregate U.S. dollar exposure from transactions or instruments that reference the relative return of a non-U.S. currency or currencies as compared to the U.S. dollar to 20% of its total assets. The Fund may also invest up to 10% of its total assets in preferred securities.

Effective December 22, 2025, “Model Risk” in the “Description of Principal Risks” section of the Offering Memorandum is deleted in its entirety and replaced with the following:

In making investment allocation decisions, PIMCO or the Sub-Adviser may utilize proprietary quantitative models. These models are used by PIMCO or the Sub-Adviser to determine the Fund’s investment allocation decisions. The Fund’s investment models used in making investment allocation decisions may not adequately take into account certain factors, may contain design flaws or faulty assumptions, and may rely on incomplete or inaccurate data, any of which may result in a decline in the value of the investment. There can be no assurance that the models used by PIMCO or the Sub-Adviser will remain viable, due to various factors, which may include the quality of the data input into the models and the assumptions underlying such models, which to varying degrees involve the exercise of judgment, as well as the possibility of errors in constructing or using the model.

The success of models relies on accurate market data inputs. If inaccurate market data is entered into a model, the resulting information will be incorrect. In addition, the models used may be predictive in nature and such models may result in an incorrect assessment of future events. The models evaluate securities or securities markets based on certain assumptions concerning the interplay of market factors. The markets or the prices of individual securities may be affected by factors not foreseen in developing the models. The performance of the investment models may be impacted by software or other technology malfunctions, human error, programming inaccuracies, and other similar circumstances. In addition, when relying on a quantitative model and/or data supplied by third parties, PIMCO or the Sub-Adviser may have less insight into the construction, coding or testing of the third-party model or data, and PIMCO or the Sub-Adviser will be exposed to systems, cyber security and other risks associated with the third party that provides the model or data.

The use of models can be complex and involves financial, economic, econometric and statistical theories, research and modeling; and the results of those processes must then be translated into computer code. Although PIMCO or the Sub-Adviser seeks to hire individuals and/or third parties, as applicable, skilled in each of these functions and to provide appropriate levels of oversight, the complexity of the individual tasks, the difficulty of

integrating such tasks, and the limited ability to perform “real world” testing of a model’s end product raises the chances that a finished model may contain an error; one or more of such errors could adversely affect a Fund’s performance.

In addition, effective December 22, 2025, “Acquired Fund Risk” is added as a Principal Risk of investing in each Fund. Accordingly, corresponding changes are made to the table in the Section titled “Description of Principal Risks” in the Offering Memorandum and the following is added under “Description of Principal Risks” in the Offering Memorandum:

Because PIMCO All Asset: Multi-RAE PLUS Fund and PIMCO All Authority: Multi-RAE PLUS Fund may invest its assets in Acquired Funds, the risks associated with investing in the Funds may be closely related to the risks associated with the securities and other investments held by the Funds. The ability of the Funds to achieve their investment objectives may depend upon the ability of the Acquired Funds to achieve their respective investment objectives. Investments in Acquired Funds that are exchange-traded funds are also subject to market risk, tracking error, the potential for trading at a discount or premium to their net asset value, bid/ask spread risk as well as the risks of the underlying securities they hold. In addition, a Fund’s performance will be reduced by the Fund’s proportionate amount of the expenses of any Acquired Funds in which it invests. There can be no assurance that the investment objective of any Acquired Fund will be achieved. Unless a fee waiver or expense reimbursement arrangement fully covers a Fund’s investment in an Acquired Fund, shareholders in a Fund will indirectly bear fees and expenses charged by the Acquired Funds in addition to a Fund’s direct fees and expenses.

A Fund’s net asset value (“NAV”) will fluctuate in response to changes in the NAVs or market prices, as applicable, of the Acquired Funds in which it invests. The extent to which the investment performance and risks associated with a Fund correlates to those of a particular Acquired Fund will depend upon the extent to which the Fund’s assets are allocated from time to time for investment in the Acquired Fund, which may vary.

Effective December 22, 2025, the following is added as the last sentence under “Derivatives” in the “Characteristics and Risks of Securities and Investment Techniques” section of the Offering Memorandum:

Each Fund may invest in derivatives on carbon equivalent emissions allowances eligible for trading under the European Union Emissions Trading Scheme, California Cap-and-Trade Program, and Regional Greenhouse Gas Initiatives. For more information, please see Greenhouse Gas “Cap-and-Trade” Programs. A description of various risks associated with these particular instruments is included in “Investment Objectives and Policies” in the Offering Memorandum Supplement. PIMCO All Asset: Multi-Real Fund may invest in such instruments to a lesser degree.

Investors Should Retain This Supplement for Future Reference