# EDGAR Filing Document

**Accession Number:** 0001380192
**File Stem:** 0000276776-23-000027
**Filing Date:** 2023-2
**Character Count:** 70358
**Document Hash:** 210c7c691d6ff2e8e170dfdc679c9787
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000276776-23-000027.hdr.sgml**: 20230224

**ACCESSION NUMBER**: 0000276776-23-000027

**CONFORMED SUBMISSION TYPE**: 497K

**PUBLIC DOCUMENT COUNT**: 3

**FILED AS OF DATE**: 20230224

**DATE AS OF CHANGE**: 20230224

**EFFECTIVENESS DATE**: 20230224

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Pioneer Series Trust VI
- **CENTRAL INDEX KEY:** 0001380192
- **IRS NUMBER:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1031

**FILING VALUES:**
- **FORM TYPE:** 497K
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-138560
- **FILM NUMBER:** 23667644

**BUSINESS ADDRESS:**
- **STREET 1:** 60 STATE STREET
- **STREET 2:** 5TH FLOOR
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02109
- **BUSINESS PHONE:** 617-742-7825

**MAIL ADDRESS:**
- **STREET 1:** 60 STATE STREET
- **STREET 2:** 5TH FLOOR
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02109

## Series and Classes Contracts Data

### Pioneer Flexible Opportunities Fund (Series ID: S000028857)

| Class ID   | Class Name                                          | Ticker Symbol   |
|:---|:---|:---|
| C000088499 | Pioneer Flexible Opportunities Fund: Class A Shares | PMARX           |
| C000088500 | Pioneer Flexible Opportunities Fund: Class C Shares | PRRCX           |
| C000088501 | Pioneer Flexible Opportunities Fund: Class Y Shares | PMYRX           |
| C000133350 | Pioneer Flexible Opportunities Fund: Class R Shares | MUARX           |
| C000200524 | Pioneer Flexible Opportunities Fund: Class K        | FLEKX           |

**Pioneer Flexible Opportunities Fund** 

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| | | | | |
|:---|:---|:---|:---|:---|
| **Class A Shares** | **Class C Shares** | **Class K Shares** | **Class R Shares** | **Class Y Shares** |
| **PMARX** | **PRRCX** | **FLEKX** | **MUARX** | **PMYRX** |

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Summary Prospectus \| March 1, 2023

**Before you invest, you may want to review the fund's prospectus, which contains more information about the fund and its risks. You can find the fund's prospectus, statement of additional information, reports to shareholders, and other information about the fund online at https://www.amundi.com/usinvestors/Resources/Download-Literature. You also can obtain this information at no cost by calling 1-800-225-6292 or by sending an email request to US.AskAmundiUS@amundi.com. The fund's current** [**prospectus and statement of additional**](https://www.sec.gov/ix?doc=/Archives/edgar/data/1380192/000119312523048630/d446886d485bpos.htm)[**information**](https://www.sec.gov/ix?doc=/Archives/edgar/data/1380192/000119312523048630/d446886d485bpos.htm)**, dated March 1, 2023, and the independent registered public accounting firm's report and** [**financial statements**](https://www.sec.gov/Archives/edgar/data/1380192/000182126823000017/pio84863.htm) **in the fund's annual report to shareholders dated October 31, 2022, are incorporated by reference into this summary prospectus.**

![](covers_amundipioneer2.jpg)

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**Summary Prospectus**

**Investment objective**

The fund's investment objective is total return.

**Fees and expenses of the fund**

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the fund. **You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.**

You may qualify for sales charge discounts if you or your family invest, or agree to invest in the future, at least $100,000 in Class A shares of the Pioneer funds. More information about these and other discounts is available from your investment professional and in the "Sales charges" section of the prospectus beginning on page 83, the "Intermediary defined sales charge waiver policies" section of the prospectus beginning on page 121, and the "Sales charges" section of the statement of additional information beginning on page 68. If you invest in Class K shares or Class Y shares through an investment professional or financial intermediary, that investment professional or financial intermediary may charge you a commission. Such commissions, if any, are not charged by the fund and are not reflected in the fee table or expense example below.

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**Shareowner fees** <br>(fees paid directly from your investment)

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| | | | | | |
|:---|:---|:---|:---|:---|:---|
|  | **Class A** | **Class C** | **Class K** | **Class R** | **Class Y** |
| Maximum sales charge (load) when you buy shares <br> (as a percentage of offering price)<br>| 4.50% |  |  |  |  |
| Maximum deferred sales charge (load) (as a <br> percentage of offering price or the amount you <br> receive when you sell shares, whichever is less)<br>| None<sup>1</sup> <br>| 1% |  |  |  |

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**Annual fund operating expenses** <br>(expenses that you pay each year as a percentage of the value of your investment)

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| | | | | | |
|:---|:---|:---|:---|:---|:---|
|  | **Class A** | **Class C** | **Class K** | **Class R** | **Class Y** |
| Management Fees | 0.70% | 0.70% | 0.70% | 0.70% | 0.70% |
| Distribution and Service (12b-1) Fees | 0.25% | 1.00% | 0.00% | 0.50% | 0.00% |
| Other Expenses |  |  |  |  |  |
| Other Expenses of the Fund | 0.27% | 0.28% | 0.19% | 0.39% | 0.28% |
| Total Other Expenses | 0.27% | 0.28% | 0.19% | 0.39% | 0.28% |
| Acquired Fund Fees and Expenses<sup>2</sup> <br>| 0.05% | 0.05% | 0.05% | 0.05% | 0.05% |
| Total Annual Fund Operating Expenses Plus <br> Acquired Fund Fees and Expenses<sup>2</sup> <br>| 1.27% | 2.03% | 0.94% | 1.64% | 1.03% |
| Less: Fee Waiver and Expense Reimbursement<sup>3</sup> <br>| -0.02% | 0.00% | 0.00% | 0.00% | -0.08% |
| Net Expenses Plus Acquired Fund Fees and <br> Expenses<sup>3</sup> <br>| 1.25% | 2.03% | 0.94% | 1.64% | 0.95% |

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Class A purchases of $500,000 or more that are not subject to an initial sales charge may be subject to a contingent deferred sales charge of 1%. See "Sales charges."

Total annual fund operating expenses in the table, before and after fee waivers and expense reimbursements, are higher than the corresponding ratios of expenses to average net assets shown in the "Financial Highlights" section, which do not include acquired fund fees and expenses.

The fund's investment adviser has contractually agreed to limit ordinary operating expenses (ordinary operating expenses means all fund expenses other than taxes, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, such as litigation) to the extent required to reduce fund expenses to 1.20% and 0.90% of the average daily net assets attributable to Class A and Class Y shares, respectively. These expense limitations are in effect through March 1, 2024. There can be no assurance that the adviser will extend these expense limitations beyond such time. Net expenses for a Class may exceed the applicable expense limitation to the extent that the fund incurs excluded expenses. While in effect, the arrangement may be terminated for a class only by agreement of the adviser and the Board of Trustees.

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**Summary Prospectus**

**Example**

This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the fund for the time periods shown and then, except as indicated, redeem all of your shares at the end of those periods. It also assumes that (a) your investment has a 5% return each year and (b) the fund's total annual operating expenses remain the same except for year one (which considers the effect of the expense limitation). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

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| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
|  | **If you redeem your shares** | **If you redeem your shares** | **If you redeem your shares** | **If you redeem your shares** | **If you do not redeem your shares** | **If you do not redeem your shares** | **If you do not redeem your shares** | **If you do not redeem your shares** |
|  | **Number of years you own your shares** | **Number of years you own your shares** | **Number of years you own your shares** | **Number of years you own your shares** | **Number of years you own your shares** | **Number of years you own your shares** | **Number of years you own your shares** | **Number of years you own your shares** |
|  | **1** | **3** | **5** | **10** | **1** | **3** | **5** | **10** |
| Class A | $572 | $833 | $1114 | $1913 | $572 | $833 | $1114 | $1913 |
| Class C | 306 | 637 | 1093 | 2358 | 206 | 637 | 1093 | 2358 |
| Class K | 96 | 300 | 520 | 1155 | 96 | 300 | 520 | 1155 |
| Class R | 167 | 517 | 892 | 1944 | 167 | 517 | 892 | 1944 |
| Class Y | 97 | 320 | 561 | 1252 | 97 | 320 | 561 | 1252 |

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**Portfolio turnover**

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 166% of the average value of its portfolio.

**Principal investment strategies**

The fund selects investments from a broad spectrum of asset classes, including both traditional investments, such as equity and fixed income securities, and less traditional or alternative investments, such as commodity-oriented investments, real estate related investments, and currencies. The fund seeks "real return" by holding some investments that historically have not moved in step with broad equity and fixed income markets and selecting investments believed to provide total return in consideration of perceived risk and changing market and economic conditions over time. Real return is considered to be a level of total return that exceeds the rate of inflation over the course of different market environments.

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Equity securities may include common and preferred stocks, depositary receipts, warrants, rights, equity-linked securities and other equity interests. The fund may invest in securities of issuers of any market capitalization. The fund may invest in initial public offerings of equity securities. In addition to direct investment in securities and other instruments, the fund may invest in other funds, including exchange-traded funds ("ETFs"), unit investment trusts, and other pooled investment vehicles that may or may not be registered under the Investment Company Act of 1940 (the "1940 Act"). Some of these funds may be managed by the adviser. The fund may invest in real estate investment trusts ("REITs") and U.S. and non-U.S. real estate companies.

Fixed income securities include those issued by U.S. and non-U.S. governmental, corporate and other issuers, including mortgage-related or mortgage-backed securities (including "sub-prime" mortgages), asset-backed securities, floating rate loans, convertible securities, Treasury Inflation Protected Securities ("TIPS") and other inflation-linked debt securities, subordinated debt securities, insurance-linked securities and municipal securities. The fund may invest in debt securities of any credit quality, including those rated below investment grade (known as "junk bonds") or, if unrated, of equivalent credit quality as determined by the fund's investment adviser. The fund may invest in securities of any maturity. The maturity of a fixed income security is a measure of the time remaining until final payment on the security is due.

The fund's investments may have fixed or variable principal payments and all types of interest rate payment and reset terms, including fixed rate, floating rate, inverse floating rate, zero coupon, contingent, deferred and payment in kind and auction rate features. The fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis.

The fund may gain exposure to commodities (such as oil and precious metals) through investment in commodity-linked derivatives, ETFs and other pooled investment vehicles, exchange-traded notes (ETNs) and leveraged or unleveraged commodity-linked notes (derivative debt instruments with principal and/or coupon payments linked to the performance of commodity indices). The fund also may invest in equity securities of issuers in commodity-related industries. The fund may gain exposure to commodities through investment in a wholly owned subsidiary of the fund organized under the laws of the Cayman Islands (the "Subsidiary") that is expected to invest in commodity-oriented investments. The fund may invest up to 25% of its total assets in the Subsidiary. The Subsidiary is advised by the adviser.

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**Summary Prospectus**

The fund may, but is not required to, use derivatives, such as stock index futures, currency futures, forward foreign currency exchange contracts, and index-based total return swap contracts. The fund may use derivatives for a variety of other purposes, including: in an attempt to hedge against adverse changes in the market price of securities, interest rates or currency exchange rates; as a substitute for purchasing or selling securities; to attempt to increase the fund's return as a non-hedging strategy that may be considered speculative; to manage portfolio characteristics; and as a cash flow management technique. The fund may invest without limit in derivative instruments (other than commodity-related derivative instruments). However, the fund may choose not to make use of derivatives for a variety of reasons, and any use may be limited by applicable law and regulations.

The fund may invest up to 100% of its assets in non-U.S. securities, including securities of emerging market issuers. In addition to investing in securities denominated in non-U.S. currencies, the fund may hold non-U.S. currencies and purchase and sell forward currency exchange contracts in non-U.S. currencies. The fund's currency and currency-related investments may be used to adjust overall currency exposures, including as a means of seeking incremental return, which may be considered a speculative technique.

The fund may take a short position with respect to a security, index or currency, for which the adviser has a negative tactical view, either through the short sale of a security or through a derivative position, such as a futures contract or swap agreement.

The fund may invest up to 100% of its assets in cash and short-term investments as a means of pursuing its investment strategies or for defensive purposes.

As part of its investment strategies, the fund may engage in active and frequent trading of portfolio securities.

In selecting investments, the adviser initially constructs an overall asset allocation model based on its expectations for economic growth and inflation on a global basis. In selecting among asset classes, the adviser considers the relative return potential of particular asset classes in view of their expected relative volatility (the variability of returns from one period to the next). The goal of this process is to identify a combination of asset classes with the potential to provide real return due to a favorable overall risk/return profile. In selecting investments within each asset class, the adviser considers the potential to provide incremental return to the portfolio consistent with the expectations for the asset class. When investing in equity and debt securities, the adviser generally favors those securities it perceives

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to be undervalued. Investments typically are sold when the adviser's overall assessment of market and economic conditions changes or the assessments of the attributes of asset classes or individual holdings change.

The fund is not required to allocate its investments among asset classes in any fixed proportion, nor is it limited by the issuer's geographic location, size or market capitalization. The fund may have none, some or all of its assets invested in each asset class in relative proportions that change over time based upon market and economic conditions.

The 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 's 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 's adviser generally considers ESG information in the context of an issuer's respective sector or industry. The 's 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 's adviser to ESG considerations in making investment decisions will vary and, for any specific decision, they may be given little or no weight. Notwithstanding the foregoing, the 's adviser generally will not invest fund assets in (i) companies that the 's adviser determines have significant involvement in the manufacturing of complete tobacco products, (ii) companies engaged in the production, sale, storage of, or providing services for, certain controversial weapons, including chemical, biological and depleted uranium weapons and certain antipersonnel mines and cluster bombs, or (iii) companies with involvement in the production or sale of nuclear weapons.

**Principal risks of investing in the fund**

You could lose money on your investment in the fund. As with any mutual fund, there is no guarantee that the fund will achieve its objective.

**Market risk.** The market prices of securities or other assets held by the fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, political instability, recessions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets, the spread of infectious illness or other public health issues, armed conflict, market disruptions caused by tariffs, trade disputes,

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**Summary Prospectus**

sanctions or other government actions, or other factors or adverse investor sentiment. If the market prices of the fund's securities and assets fall, the value of your investment will go down. A change in financial condition or other event affecting a single issuer or market may adversely impact securities markets as a whole.

In the past decade, financial markets throughout the world have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. Governmental and non-governmental issuers have defaulted on, or been forced to restructure, their debts. These conditions may continue, recur, worsen or spread. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events; geopolitical events (including wars, terror attacks and economic sanctions); measures to address budget deficits; downgrading of sovereign debt; changes in oil and commodity prices; dramatic changes in currency exchange rates; global pandemics; and public sentiment. The fallout from the COVID-19 pandemic and subsequent variants of COVID-19, and the long-term impact on economies, markets, industries and individual issuers, are not known. Some sectors of the economy and individual issuers have experienced or may experience particularly large losses. Periods of extreme volatility in the financial markets; reduced liquidity of many instruments; and disruptions to supply chains, consumer demand and employee availability, may continue for some time.

Raising the ceiling on U.S. government debt has become increasingly politicized. Any failure to increase the ceiling on U.S. government debt could lead to a default on U.S. government obligations, with unpredictable consequences for economies and markets in the U.S. and elsewhere. Recently, inflation and interest rates have increased and may rise further. These circumstances could adversely affect the value and liquidity of the fund's investments, impair the fund's ability to satisfy redemption requests, and negatively impact the fund's performance. Following Russia's invasion of Ukraine, Russian securities have lost all, or nearly all, their market value. Other securities or markets could be similarly affected by past or future political, geopolitical or other events or conditions.

Governments and central banks, including the U.S. Federal Reserve, have taken extraordinary and unprecedented actions to support local and global economies and the financial markets. These actions have resulted in significant expansion of public debt, including in the U.S. The consequences of high public debt, including its future impact on the economy and securities markets, may not be known for some time. U.S. Federal Reserve or other U.S. or non-U.S. governmental or central bank actions, including increases or decreases in interest rates, or contrary actions by different governments, could negatively affect financial markets generally, increase market volatility and reduce the value and liquidity of securities in which

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the fund invests. Policy and legislative changes in the U.S. and in other countries are affecting many aspects of financial regulation, and these and other events affecting global markets, such as the United Kingdom's exit from the European Union (or Brexit), potential trade imbalances with China or other countries or sanctions or other government actions against Russia, other nations or individuals or companies (or their countermeasures), may contribute to decreased liquidity and increased volatility in the financial markets. The impact of these changes on the markets, and the implications for market participants, may not be fully known for some time.

The United States and other countries are periodically involved in disputes over trade and other matters, which may result in tariffs, investment restrictions and adverse impacts on affected companies and securities. For example, the United States has imposed tariffs and other trade barriers on Chinese exports, has restricted sales of certain categories of goods to China, and has established barriers to investments in China. Trade disputes may adversely affect the economies of the United States and its trading partners, as well as companies directly or indirectly affected and financial markets generally. The United States government has prohibited U.S. persons, such as the fund, from investing in Chinese companies designated as related to the Chinese military. These and possible future restrictions could limit the fund's opportunities for investment and require the sale of securities at a loss or make them illiquid. Moreover, the Chinese government is involved in a longstanding dispute with Taiwan that has included threats of invasion. If the political climate between the United States and China does not improve or continues to deteriorate, if China were to attempt unification of Taiwan by force, or if other geopolitical conflicts develop or get worse, economies, markets and individual securities may be severely affected both regionally and globally, and the value of the fund's assets may go down.

Economies and financial markets throughout the world are increasingly interconnected. Economic, financial or political events, trading and tariff arrangements, armed conflict including Russia's military invasion of Ukraine, terrorism, natural disasters, infectious illness or public health issues, cybersecurity events, supply chain disruptions, sanctions against Russia, other nations or individuals or companies and possible countermeasures, and other circumstances in one country or region could have profound impacts on other countries or regions and on global economies or markets. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to the countries or regions directly affected, the value and liquidity of the fund's investments may be negatively affected. The fund may experience a substantial or complete loss on any security or derivative position.

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**Summary Prospectus**

**Derivatives risk.** Using stock index futures and options, forward foreign currency exchange contracts, index-based total return swap contracts, and other derivatives can increase fund losses and reduce opportunities for gains when market prices, interest rates, currencies or the derivative instruments themselves behave in a way not anticipated by the fund. Using derivatives may increase the volatility of the fund's net asset value and may not provide the result intended. Derivatives may have a leveraging effect on the fund. Some derivatives have the potential for unlimited loss, regardless of the size of the fund's initial investment. Derivatives are generally subject to the risks applicable to the assets, rates, indices or other indicators underlying the derivative. Changes in a derivative's value may not correlate well with the referenced asset or metric. The fund also may have to sell assets at inopportune times to satisfy its obligations. Derivatives may be difficult to sell, unwind or value, and the counterparty may default on its obligations to the fund. Use of derivatives may have different tax consequences for the fund than an investment in the underlying security, and such differences may affect the amount, timing and character of income distributed to shareholders. The U.S. government and foreign governments have adopted and implemented or are in the process of adopting and implementing regulations governing derivatives markets, including mandatory clearing of certain derivatives, margin and reporting requirements. The ultimate impact of the regulations remains unclear. Additional regulation of derivatives may make them more costly, limit their availability or utility, otherwise adversely affect their performance or disrupt markets.

**Credit default swap risk.** Credit default swap contracts, a type of derivative instrument, involve special risks and may result in losses to the fund. Credit default swaps may in some cases be illiquid, and they increase credit risk since the fund has exposure to the issuer of the referenced obligation and either the counterparty to the credit default swap or, if it is a cleared transaction, the brokerage firm through which the trade was cleared and the clearing organization that is the counterparty to that trade.

**Risks of investing in inverse floating rate obligations.** The interest rate on inverse floating rate obligations will generally decrease as short-term interest rates increase, and increase as short-term rates decrease. Due to their leveraged structure, the sensitivity of the market value of an inverse floating rate obligation to changes in interest rates is generally greater than a comparable long-term bond issued by the same issuer and with similar credit quality, redemption and maturity provisions. Inverse floating rate obligations may be volatile and involve leverage risk.

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**Forward foreign currency transactions risk.** The fund may not fully benefit from or may lose money on forward foreign currency transactions if changes in currency rates do not occur as anticipated or do not correspond accurately to changes in the value of the fund's holdings, or if the counterparty defaults. Such transactions may also prevent the fund from realizing profits on favorable movements in exchange rates. Risk of counterparty default is greater for counterparties located in emerging markets.

**Short position risk.** Taking short positions involves leverage of the fund's assets and presents various risks. If the price of the instrument or market on which the fund has taken a short position increases, then the fund will incur a loss, which may be substantial. Because of leverage, taking short positions involves the risk that losses may be exaggerated, potentially more than the actual cost of the investment. Unlike purchasing a financial instrument like a stock, where potential losses are limited to the purchase price and there is no upside limit on potential gain, short sales involve no cap on maximum losses. Also, there is the risk that a counterparty may fail to perform the terms of the arrangement, causing a loss to the fund.

**Leveraging risk.** The value of your investment may be more volatile and other risks tend to be compounded if the fund borrows or uses derivatives or other investments, such as ETFs, that have embedded leverage. Leverage generally magnifies the effect of any increase or decrease in the value of the fund's underlying assets and creates a risk of loss of value on a larger pool of assets than the fund would otherwise have, potentially resulting in the loss of all assets. Engaging in such transactions may cause the fund to liquidate positions when it may not be advantageous to do so to satisfy its obligations. New derivatives regulations require the fund, to the extent it uses derivatives to a material extent, to, among other things, comply with certain overall limits on leverage. These regulations may limit the ability of the fund to pursue its investment strategies and may not be effective to mitigate the fund's risk of loss from derivatives.

**Commodity investments risk.** Exposure to the commodities markets may subject the fund to greater volatility than investments in other securities. The value of commodity-linked notes and other commodity-linked derivatives may be affected by changes in overall market movements, commodity index volatility, changes in interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments. The prices of energy, industrial metals, precious metals, agriculture and livestock sector commodities may fluctuate widely and rapidly due to factors such as changes in value, supply and demand and governmental regulatory policies. Commodity-related investments may be

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**Summary Prospectus**

more volatile and less liquid than the underlying commodities, instruments or measures, which may make it difficult for such investments to be sold at a price acceptable to the adviser or to accurately value them. Commodity-related investments are subject to the credit risks associated with the issuer, and their values may decline substantially if the issuer's creditworthiness deteriorates. As a result, returns of commodity-linked investments may deviate significantly from the return of the underlying commodity, instruments or measures. If the fund has taken a long or short position in a commodity using futures contracts or other derivatives, it might be required to take or make delivery of the underlying commodity under undesirable circumstances. This would cause the fund to incur a number of costs. The fund intends to gain exposure to commodities by investing in the Subsidiary, a foreign entity that will be treated as a corporation for U.S. federal income tax purposes. The fund's ability to invest in commodity-related investments, and the means through which any such investments may be made, will be limited by tax considerations.

**Tax Risk.** To qualify for the tax treatment available to regulated investment companies under the Code, the fund must derive at least 90% of its gross income for each taxable year from sources treated as "qualifying income." Income derived from direct investments in commodities is not "qualifying income." In addition, the Internal Revenue Service has issued a revenue ruling concluding that income and gains from certain commodity-linked derivatives does not constitute "qualifying income."

The fund has obtained a private letter ruling from the Internal Revenue Service establishing that income derived from the Subsidiary will be permissible income for purposes of the 90% income test. There can be no assurance that the Internal Revenue Service will not revoke the private letter ruling it issued to the fund. It is possible that any such revocation could be retroactive to a date to be specified by the Internal Revenue Service. The tax treatment of the Fund's investment in commodity interests or in the Subsidiary could also be adversely affected by future legislation or Treasury regulations.

**Risks of investing in the Subsidiary.** The Subsidiary is not registered under the 1940 Act and is not subject to all of the investor protections of the 1940 Act. Thus, the fund, as an investor in the Subsidiary, will not have all of the regulatory protections offered to investors in registered investment companies. In addition, changes in the laws of the United States and/or the Cayman Islands, under which the fund and the Subsidiary, respectively, are organized, could affect the ability of the fund and/or the Subsidiary to operate as described in this prospectus and could negatively affect the fund and its shareholders.

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**Risks of non-U.S. investments.** Investing in non-U.S. issuers, or in U.S. issuers that have significant exposure to foreign markets, may involve unique risks compared to investing in securities of U.S. issuers. These risks are more pronounced for issuers in emerging markets or to the extent that the fund invests significantly in one region or country. These risks may include different financial reporting practices and regulatory standards, less liquid trading markets, extreme price volatility, currency risks, changes in economic, political, regulatory and social conditions, military conflicts and sanctions, terrorism, sustained economic downturns, financial instability, reduction of government or central bank support, inadequate accounting standards, tariffs, tax disputes or other tax burdens, nationalization or expropriation of assets, arbitrary application of laws and regulations or lack of rule of law, and investment and repatriation restrictions. Lack of information and less market regulation also may affect the value of these securities. Withholding and other non-U.S. taxes may decrease the fund's return. Non-U.S. issuers may be located in parts of the world that have historically been prone to natural disasters. Emerging market economies tend to be less diversified than those of more developed countries. They typically have fewer medical and economic resources than more developed countries and thus they may be less able to control or mitigate the effects of a pandemic. Investing in depositary receipts is subject to many of the same risks as investing directly in non-U.S. issuers. Depositary receipts may involve higher expenses and may trade at a discount (or premium) to the underlying security.

A number of countries in the European Union (EU) have experienced, and may continue to experience, severe economic and financial difficulties. In addition, the United Kingdom has withdrawn from the EU (commonly known as "Brexit"). The range and potential implications of possible political, regulatory, economic, and market outcomes of Brexit cannot be fully known but could be significant, potentially resulting in increased volatility, illiquidity and potentially lower economic growth in the affected markets, which will adversely affect the fund's investments.

If one or more stockholders of a supranational entity such as the World Bank fail to make necessary additional capital contributions, the entity may be unable to pay interest or repay principal on its debt securities. <br>

Sanctions or other government actions against certain countries could negatively impact the fund's investments in securities that have exposure to those countries. Circumstances that impact one country could have profound impacts on other countries and on global economies or markets. China and other developing market countries may be subject to considerable degrees of economic, political and social instability. The U.S. government has imposed restrictions on U.S. investor participation in certain Chinese investments. These matters could adversely affect China's

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**Summary Prospectus**

economy. In addition, China's long-running conflict over Taiwan's sovereignty, border disputes with many neighbors and historically strained relations with other Asian countries could result in military conflict that could adversely impact the economies of China and other Asian countries, disrupt supply chains, and severely affect global economies and markets.

Russia launched a large-scale invasion of Ukraine on February 24, 2022. In response to the military action by Russia, various countries, including the U.S., the United Kingdom, and European Union, issued broad-ranging economic sanctions against Russia and Belarus and certain companies and individuals. Russia has taken retaliatory actions, including preventing repatriation of capital by U.S. and other investors. Since then, Russian securities have lost all, or nearly all, their market value, and many other issuers, securities and markets have been adversely affected. The ongoing conflict has resulted in significant market disruptions, including in certain markets, industries and sectors, such as the oil and natural gas markets, and negatively affected global supply chains, food supplies, inflation and global growth. The U.S. and other countries may impose sanctions on other countries, companies and individuals in light of Russia's military invasion. The extent and duration of the military action or future escalation of such hostilities, the extent and impact of existing and future sanctions, market disruptions and volatility, and the result of any diplomatic negotiations cannot be predicted. These and any related events could have a significant impact on the value and liquidity of certain fund investments, on fund performance and the value of an investment in the fund.

**Currency risk.** The fund could experience losses based on changes in the exchange rate between non-U.S. currencies and the U.S. dollar or as a result of currency conversion costs. Currency exchange rates can be volatile, and are affected by factors such as general economic conditions, the actions of the U.S. and foreign governments or central banks, the imposition of currency controls and speculation.

**Equity securities risk.** Equity securities represent an ownership interest in an issuer, rank junior in a company's capital structure to debt securities and consequently may entail greater risk of loss than debt securities. Equity securities are subject to the risk that stock prices may rise and fall in periodic cycles and may perform poorly relative to other investments. This risk may be greater in the short term.

**Small and mid-size companies risk.** Compared to large companies, small- and mid-size companies, and the market for their equity securities, may be more sensitive to changes in earnings results and investor expectations, or poor economic or market conditions, including those experienced during a recession, have more limited product lines, operating histories, markets or capital resources, may be

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dependent upon a limited management group, experience sharper swings in market values, have limited liquidity, be harder to value or to sell at the times and prices the adviser thinks appropriate, and offer greater potential for gain and loss.

**Risks of investments in real estate related securities.** Investments in real estate securities are affected by economic conditions, interest rates, governmental actions and other factors. In addition, investing in REITs involves unique risks. They are significantly affected by the market for real estate and are dependent upon management skills and cash flow. REITs may have lower trading volumes and may be subject to more abrupt or erratic price movements than the overall securities markets. Mortgage REITs are particularly subject to interest rate and credit risks. In addition to its own expenses, the fund will indirectly bear its proportionate share of any management and other expenses paid by REITs in which it invests. Many real estate companies, including REITs, utilize leverage.

**Risks of initial public offerings.** Companies involved in initial public offerings (IPOs) generally have limited operating histories, and prospects for future profitability are uncertain. The market for IPO issuers has been volatile, and share prices of newly public companies have fluctuated significantly over short periods of time. The purchase of IPO shares may involve high transaction costs.

**Risks of convertible securities.** The market values of convertible securities tend to decline as interest rates increase and, conversely, to increase as interest rates decline. A downturn in equity markets may cause the price of convertible securities to decrease relative to other fixed income securities.

**Preferred stocks risk.** Preferred stocks may pay fixed or adjustable rates of return. Preferred stocks are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company's preferred stocks generally pay dividends only after the company makes required payments to holders of its bonds and other debt. Thus, the value of preferred stocks will usually react more strongly than bonds and other debt to actual or perceived changes in the company's financial condition or prospects. The market value of preferred stocks generally decreases when interest rates rise. Also, the market prices of preferred stocks are more sensitive to changes in the issuer's creditworthiness than are the prices of debt securities. Generally, under normal circumstances, preferred stocks do not carry voting rights. Preferred stocks may trade less frequently and in a more limited volume and may be subject to more abrupt or erratic price movements than other securities. Preferred stocks of smaller companies may be more vulnerable to adverse developments than preferred stocks of larger companies.

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**Summary Prospectus**

**Risks of warrants and rights.** If the price of the underlying stock does not rise above the exercise price before the warrant expires, the warrant generally expires without any value and the fund loses any amount it paid for the warrant. The failure to exercise subscription rights to purchase common shares would result in the dilution of the fund's interest in the issuing company.

**Risks of investment in other funds.** Investing in other investment companies, including exchange-traded funds (ETFs) and closed-end funds, subjects the fund to the risks of investing in the underlying securities or assets held by those funds. When investing in another fund, the fund will bear a pro rata portion of the underlying fund's expenses, including management fees, in addition to its own expenses. ETFs and closed-end funds are bought and sold based on market prices and can trade at a premium or a discount to the ETF's or closed-end fund's net asset value. Such funds may trade at a discount for an extended period and may not ever realize their net asset value.

**Interest rate risk**.The market prices of the fund's fixed income securities may fluctuate significantly when interest rates change. The value of your investment will generally go down when interest rates rise. A rise in rates tends to have a greater impact on the prices of longer term or duration securities. For example, if interest rates increase by 1%, the value of a fund's portfolio with a portfolio duration of ten years would be expected to decrease by 10%, all other things being equal. In recent years, interest rates and credit spreads in the U.S. have been at historic lows. The U.S. Federal Reserve has raised certain interest rates, and interest rates may continue to go up. A general rise in interest rates could adversely affect the price and liquidity of fixed income securities and could also result in increased redemptions from the fund. The maturity of a security may be significantly longer than its effective duration. A security's maturity and other features may be more relevant than its effective duration in determining the security's sensitivity to other factors affecting the issuer or markets generally, such as changes in credit quality or in the yield premium that the market may establish for certain types of securities (sometimes called "credit spread"). In general, the longer its maturity the more a security may be susceptible to these factors. When the credit spread for a fixed income security goes up or "widens," the value of the security will generally go down.

**Credit risk.** If an issuer or guarantor of a security held by the fund or a counterparty to a financial contract with the fund defaults on its obligation to pay principal and/or interest, has its credit rating downgraded or is perceived to be less creditworthy, or the credit quality or value of any underlying assets declines, the value of your

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investment will typically decline. Changes in actual or perceived creditworthiness may occur quickly. The fund could be delayed or hindered in its enforcement of rights against an issuer, guarantor or counterparty.

**Prepayment or call risk.** Many issuers have a right to prepay their securities. If interest rates fall, an issuer may exercise this right. If this happens, the fund will not benefit from the rise in market price that normally accompanies a decline in interest rates, and will be forced to reinvest prepayment proceeds at a time when yields on securities available in the market are lower than the yield on the prepaid security. The fund also may lose any premium it paid on the security.

**Extension risk.** During periods of rising interest rates, the average life of certain types of securities may be extended because of slower than expected principal payments. This may lock in a below market interest rate, increase the security's duration and reduce the value of the security.

**Liquidity risk.** Some securities and derivatives held by the fund may be or become impossible or difficult to purchase, sell or unwind, particularly during times of market turmoil. An instrument's liquidity may be affected by reduced trading volume, a relative lack of market makers or legal restrictions, and illiquid securities and derivatives also may be difficult to value. Liquidity risk may be magnified in an environment of rising interest rates or widening credit spreads. During times of market turmoil, there have been, and may be, no buyers or sellers for securities in entire asset classes. If the fund is forced to sell an illiquid asset or unwind a derivative position to meet redemption requests or other cash needs, or to try to limit losses, the fund may be forced to sell at a substantial loss or may not be able to sell at all. The fund may not receive its proceeds from the sale of certain securities for an extended period (for example, several weeks or even longer). In extreme cases, this may constrain the fund's ability to meet its obligations (including obligations to redeeming shareholders).

**Portfolio selection risk.** The adviser's judgment about a particular security or issuer, or about the economy or a particular sector, region, market segment or industry, or about an investment strategy, may prove to be incorrect or may not produce the desired results, or there may be imperfections, errors or limitations in the models, tools and information used by the adviser.

**ESG risk.** The fund's adviser may consider ESG information in its investment research process. This may mean forgoing some investment opportunities available to funds that do not consider ESG information. In considering ESG information, the adviser may use third party ESG ratings information that it believes to be reliable, but such information may not be accurate or complete, or may be biased.

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**Summary Prospectus**

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.

**Inflation-linked securities risk.** The principal or interest of inflation-linked securities such as TIPS is adjusted periodically to a specified rate of inflation. The inflation index used may not accurately measure the real rate of inflation. Inflation-linked securities may lose value or interest payments on such securities may decline in the event that the actual rate of inflation is different than the rate of the inflation index, and losses may exceed those experienced by other debt securities with similar durations. The values of inflation-linked securities may not be directly correlated to changes in interest rates, for example if interest rates rise for reasons other than inflation.

**U.S. Treasury obligations risk.** The market value of direct obligations of the U.S. Treasury may vary due to changes in interest rates. In addition, changes to the financial condition or credit rating of the U.S. government may cause the value of the fund's investments in obligations issued by the U.S. Treasury to decline.

**U.S. government agency obligations risk.** The fund invests in obligations issued by agencies and instrumentalities of the U.S. government. Government-sponsored entities such as the Federal National Mortgage Association (FNMA), the Federal Home Loan Mortgage Corporation (FHLMC) and the Federal Home Loan Banks (FHLBs), although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt and mortgage-backed securities issued by them are neither guaranteed nor issued by the U.S. government. The maximum potential liability of the issuers of some U.S. government obligations may greatly exceed their current resources, including any legal right to support from the U.S. government. Such debt and mortgage-backed securities are subject to the risk of default on the payment of interest and/or principal, similar to debt of private issuers. Although the U.S. government has provided financial support to FNMA and FHLMC in the past, there can be no assurance that it will support these or other government-sponsored entities in the future.

**Sovereign debt risk.** A governmental entity may delay, refuse or be unable to pay interest or principal on its sovereign debt due to cash flow problems, insufficient foreign currency reserves, political considerations, the relative size of the governmental entity's debt position in relation to the economy or the failure to put in place economic reforms. There may be no legal or bankruptcy process for collecting sovereign debt. Emerging markets countries tend to have economic, political and legal systems that are less fully developed and are less stable than those of more advanced countries.

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**Mortgage-related and asset-backed securities risk.** The value of mortgage-related securities, including commercial mortgage-backed securities, collateralized mortgage-backed securities, credit risk transfer securities, and asset-backed securities, will be influenced by factors affecting the assets underlying such securities. As a result, during periods of declining asset value, difficult or frozen credit markets, swings in interest rates, or deteriorating economic conditions, mortgage-related and asset-backed securities may decline in value, face valuation difficulties, become more volatile and/or become illiquid. Mortgage-backed securities tend to be more sensitive to changes in interest rates than other types of debt securities. These securities are also subject to interest rate, prepayment and extension risks. Some of these securities may receive little or no collateral protection from the underlying assets and are thus subject to the risk of default. The risk of such defaults is generally higher in the case of mortgage-backed investments offered by non-governmental issuers and those that include so-called "sub-prime" mortgages. The structure of some of these securities may be complex and there may be less available information than for other types of debt securities. Upon the occurrence of certain triggering events or defaults, the fund may become the holder of underlying assets at a time when those assets may be difficult to sell or may be sold only at a loss.

**High yield or "junk" bond risk.** Debt securities that are below investment grade, called "junk bonds," are speculative, have a higher risk of default or are already in default, tend to be less liquid and are more difficult to value than higher grade securities. Junk bonds tend to be volatile and more susceptible to adverse events and negative sentiments. These risks are more pronounced for securities that are already in default.

**Risks of investing in loans.** Floating rate loans and similar investments may be illiquid or less liquid than other investments and difficult to value. The value of collateral, if any, securing a floating rate loan can decline or may be insufficient to meet the issuer's obligations or may be difficult to liquidate. Market quotations for these securities may be volatile and/or subject to large spreads between bid and ask prices. No active trading market may exist for many floating rate loans, and many loans are subject to restrictions on resale. Any secondary market may be subject to irregular trading activity and extended trade settlement periods. In particular, loans may take longer than seven days to settle, potentially leading to the sale proceeds of loans not being available to meet redemptions for a substantial period of time after the sale of the loans. To the extent that sale proceeds of loans are not available, the fund may sell securities that have shorter settlement periods or may access other sources of liquidity to meet redemption requests. There is less readily available, reliable information about most senior loans than is the case for many

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**Summary Prospectus**

other types of securities. The adviser's decision not to receive material, non-public information about an issuer of a loan either held by, or considered for investment by, the fund, under normal circumstances could place it at a disadvantage, relative to other loan investors, in assessing a loan or the loan's issuer, and adversely affect the fund's investment performance. Loans may not be considered "securities," and purchasers, such as the fund, therefore may not be entitled to rely on the anti-fraud protections afforded by federal securities laws.

**Risks of investing in insurance-linked securities.** The fund could lose a portion or all of the principal it has invested in an insurance-linked security, and the right to additional interest and/or dividend payments with respect to the security, upon the occurrence of one or more trigger events, as defined within the terms of an insurance-linked security. Trigger events may include natural or other perils of a specific size or magnitude that occur in a designated geographic region during a specified time period, and/or that involve losses or other metrics that exceed a specific amount. The fund may also invest in insurance-linked securities that are subject to "indemnity triggers." An indemnity trigger is a trigger based on the actual losses of the ceding sponsor (i.e., the party seeking reinsurance). Insurance-linked securities subject to indemnity triggers are often regarded as being subject to potential moral hazard, since such insurance-linked securities are triggered by actual losses of the ceding sponsor and the ceding sponsor may have an incentive to take actions and/or risks that would have an adverse effect on the fund. There is no way to accurately predict whether a trigger event will occur and, accordingly, insurance-linked securities carry significant risk. In addition to the specified trigger events, insurance-linked securities may expose the fund to other risks, including but not limited to issuer (credit) default, adverse regulatory or jurisdictional interpretations and adverse tax consequences. Certain insurance-linked securities may have limited liquidity, or may be illiquid. The fund has limited transparency into the individual contracts underlying certain insurance-linked securities, which may make the risk assessment of such securities more difficult. Certain insurance-linked securities may be difficult to value.

**Risks of subordinated securities.** A holder of securities that are subordinated or "junior" to more senior securities of an issuer is entitled to payment after holders of more senior securities of the issuer. Subordinated securities are more likely to suffer a credit loss than non-subordinated securities of the same issuer, any loss incurred by the subordinated securities is likely to be proportionately greater, and any recovery of interest or principal may take more time. As a result, even a perceived decline in creditworthiness of the issuer is likely to have a greater impact on subordinated securities than more senior securities.

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**Exchange-traded note risk.** Exchange-traded notes (ETNs) are debt securities that may be traded on stock exchanges and generally are linked to the performance of an underlying index. An ETN's value generally depends on the performance of the underlying index and the credit rating of the issuer. ETNs may be held to maturity, but there are no periodic interest payments and principal is not protected. The fund is subject to the risk that the issuer of the ETN will not fulfill its contractual obligations. The market price of an ETN may be more volatile than the price of the underlying securities. The cost of owning an ETN may exceed the cost of investing directly in the underlying securities. The fund could lose some or the entire amount invested in an ETN. When the fund invests in an ETN, the fund bears its proportionate share of any fees and expenses borne by the ETN.

**Municipal securities risk.** The municipal bond market can be susceptible to unusual volatility, particularly for lower-rated and unrated securities. Liquidity can be reduced unpredictably in response to overall economic conditions or credit tightening. Municipal issuers may be adversely affected by rising health care costs, increasing unfunded pension liabilities, and by the phasing out of federal programs providing financial support. Unfavorable conditions and developments relating to projects financed with municipal securities can result in lower revenues to issuers of municipal securities, potentially resulting in defaults. Issuers often depend on revenues from these projects to make principal and interest payments. The value of municipal securities can also be adversely affected by changes in the financial condition of one or more individual municipal issuers or insurers of municipal issuers, regulatory and political developments, tax law changes or other legislative actions, and by uncertainties and public perceptions concerning these and other factors. Municipal securities may be more susceptible to downgrades or defaults during recessions or similar periods of economic stress. Financial difficulties of municipal issuers may continue or get worse, particularly in the event of political, economic or market turmoil or a recession. To the extent the fund invests significantly in a single state , city, territory (including Puerto Rico), or region, or in securities the payments on which are dependent upon a single project or source of revenues, or that relate to a sector or industry, the fund will be more susceptible to associated risks and developments.

**Risks of zero coupon bonds, payment in kind, deferred and contingent payment securities.** These securities may be more speculative and may fluctuate more in value than securities which pay income periodically and in cash. In addition, although the fund receives no periodic cash payments on such securities, the fund is deemed for tax purposes to receive income from such securities, which applicable tax rules require the fund to distribute to shareholders. Such distributions may be taxable when distributed to shareholders.

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**Summary Prospectus**

**Risks of investing in "when-issued," delayed delivery, to be announced and forward commitment transactions.** The market value of these transactions may increase or decrease as a result of changes in interest rates. These transactions involve risk of loss if the value of the underlying security changes unfavorably before the settlement date or if the assets set aside to pay for these securities decline in value prior to the settlement date. Therefore, these transactions may have a leveraging effect on the fund, making the value of an investment in the fund more volatile and increasing the fund's overall investment exposure. There is also a risk that the security will not be issued or that the other party to the transaction will default on its obligation to purchase or sell the security, which may result in the fund missing the opportunity to obtain a favorable price or yield elsewhere.

**Market segment risk.** To the extent the fund emphasizes, from time to time, investments in a market segment, the fund will be subject to a greater degree to the risks particular to that segment, and may experience greater market fluctuation than a fund without the same focus.

Industries in the financials segment, such as banks, insurance companies, broker-dealers and real estate investment trusts (REITs), may be sensitive to changes in interest rates, credit rating downgrades, decreased liquidity in credit markets, and general economic activity and are generally subject to extensive government regulation.

**Portfolio turnover risk.** If the fund does a lot of trading, it may incur additional operating expenses, which would reduce performance. A higher level of portfolio turnover may also cause shareholders to incur a higher level of taxable income or capital gains.

**Valuation risk.** The sales price the fund could receive for any particular portfolio investment may differ from the fund's valuation of the investment, particularly for illiquid securities and securities that trade in thin or volatile markets or that are valued using a fair value methodology. These differences may increase significantly and affect fund investments more broadly during periods of market volatility. Investors who purchase or redeem fund shares on days when the fund is holding fair-valued securities may receive fewer or more shares or lower or higher redemption proceeds than they would have received if the securities had not been fair-valued or if a different valuation methodology had been used. The fund's ability to value its investments may also be impacted by technological issues and/or errors by pricing services or other third party service providers.

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**Redemption risk.** The fund may experience heavy redemptions that could cause the fund to liquidate its assets at inopportune times or at a loss or depressed value, or accelerate taxable gains or transaction costs, which could cause the value of your investment to decline.

**Cybersecurity risk.** Cybersecurity failures by and breaches of the fund's adviser, transfer agent, distributor, custodian, fund accounting agent or other service providers may disrupt fund operations, interfere with the fund's ability to calculate its NAV, prevent fund shareholders from purchasing, redeeming or exchanging shares or receiving distributions or receiving timely information regarding the fund or their investment in the fund, cause loss of or unauthorized access to private shareholder information, and result in financial losses to the fund and its shareholders, regulatory fines, penalties, reputational damage, or additional compliance costs.

**Expense risk.** Your actual costs of investing in the fund may be higher than the expenses shown in "Annual fund operating expenses" for a variety of reasons. For example, expense ratios may be higher than those shown if overall net assets decrease. Net assets are more likely to decrease and fund expense ratios are more likely to increase when markets are volatile.

Please note that there are many other factors that could adversely affect your investment and that could prevent the fund from achieving its goals.

An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

**The fund's past performance**

The bar chart and table indicate the risks and volatility of an investment in the fund by showing how the fund has performed in the past. The bar chart shows changes in the performance of the fund's Class A shares from calendar year to calendar year. The table shows the average annual total returns for each class of the fund over time and compares these returns to the returns of the Bloomberg U.S. Treasury TIPS 1-10 Year Index, a broad-based measure of market performance that has characteristics relevant to the fund's investment strategies. <br> You can obtain updated performance information by visiting https://www.amundi.com/usinvestors/Products/Mutual-Funds or by calling 1-800-225-6292.

The fund's past performance (before and after taxes) does not necessarily indicate how it will perform in the future.

The bar chart does not reflect any sales charge you may pay when you buy fund shares. If this amount was reflected, returns would be less than those shown.

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**Summary Prospectus**

**Annual return Class A shares (%)**

(Year ended December 31)

![](flexibleopportunities.jpg)

For the period covered by the bar chart:

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| | | | |
|:---|:---|:---|:---|
|  | **Returns** | **Period Beginning** | **Period Ending** |
| Highest Calendar Quarter | 13.41% | 10/01/2020 to | 12/31/2020 |
| Lowest Calendar Quarter | -19.76% | 01/01/2020 to | 03/31/2020 |

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**Average annual total return (%)**

(for periods ended December 31, 2022)

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| | | | | | |
|:---|:---|:---|:---|:---|:---|
|  | **1 Year** | **5 Years** | **10 Years** | **Since**<br> **Inception**<br>| **Inception**<br> **Date** <br>|
| Class A |  |  |  |  | &nbsp;&nbsp; 5/3/10 |
| Return before taxes | -22.60 | -0.98 | 3.19 | 4.41 |  |
| Return after taxes on distributions | -23.25 | -1.97 | 1.95 | 3.33 |  |
| Return after taxes on distributions and <br> sale of shares<br>| -12.90 | -0.81 | 2.29 | 3.33 |  |
| Class C | -20.32 | -0.83 | 2.87 | 4.00 | &nbsp;&nbsp; 5/3/10 |
| Class K | -18.71 | N/A | N/A | -0.19 | 6/22/18 |
| Class R | -19.34 | -0.97 | N/A | 2.53 | 9/13/13 |
| Class Y | -18.71 | 0.23 | 3.96 | 5.10 | &nbsp;&nbsp; 5/3/10 |
| Bloomberg U.S. Treasury TIPS 1-10 Year <br> Index (reflects no deduction for fees, <br> expenses or taxes)<br>| &nbsp;&nbsp; -7.34 | 2.50 | 1.29 | 2.34 | &nbsp;&nbsp; 5/3/10 |

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor's tax situation and may differ from those shown. The after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. Returns after taxes on distributions and sale of fund shares are higher than returns before taxes for certain periods shown because they reflect the tax benefit of capital losses realized on the sale of fund shares.

After-tax returns are shown only for Class A shares. After-tax returns for Class C, Class K, Class R and Class Y shares will vary.

**Management** 

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| | |
|:---|:---|
| **Investment adviser** | Amundi Asset Management US, Inc. ("Amundi <br> US")<br>|
| **Portfolio management** | Howard Weiss, Senior Vice President and Director <br> of Multi-Asset Solutions, US of Amundi US <br> (portfolio manager of the fund since 2012); and <br> Kenneth J. Taubes, Executive Vice President and <br> Chief Investment Officer, US of Amundi US <br> (portfolio manager of the fund since 2010).<br>|

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**Summary Prospectus**

**Purchase and sale of fund shares**

You may purchase, exchange or sell (redeem) shares each day the New York Stock Exchange is open through your financial intermediary or, for accounts held directly with the fund, by contacting the fund in writing or by telephone: Pioneer Funds, P.O. Box 534427, Pittsburgh, PA 15253-4427, tel. 1-800-225-6292.

Your initial investment for Class A or Class C shares must be at least $1,000. Additional investments must be at least $100 for Class A shares and $500 for Class C shares. Generally, the initial investment for Class K or Class Y shares must be at least $5 million. This amount may be invested in one or more of the Pioneer mutual funds that currently offer Class K or Class Y shares, as applicable. There is no minimum additional investment amount for Class K or Class Y shares. There is no minimum investment amount for Class R shares.

**Tax information**

The fund intends to make distributions that may be taxed as ordinary income, qualified dividend income, or capital gains.

**Payments to broker-dealers and other financial intermediaries**

If you purchase the fund through a broker-dealer or other financial intermediary (such as a bank), the fund and its related companies may pay the intermediary for the sale of fund shares and related services. These payments create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson or investment professional to recommend the fund over another investment. Ask your salesperson or investment professional or visit your financial intermediary's website for more information.

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**Notes** 

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24557-21-0323

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