Information regarding each Fund’s principal investment strategies, principal risks and risk management strategies, the effects of each Fund’s leverage, and each Fund’s fundamental investment restrictions, including a summary of certain changes thereto during the most recent fiscal year, can be found within the relevant sections of this report. Please refer to the Table of Contents for further information.

We believe that bond funds have an important role to play in a well-diversified investment portfolio. It is important to note, however, that in an environment where interest rates may trend upward, rising rates would negatively impact the performance of most bond funds, and fixed-income securities and other instruments held by a Fund are likely to decrease in value. A wide variety of factors can cause interest rates or yields of U.S. Treasury securities (or yields of other types of bonds) to rise (e.g., central bank monetary policies, inflation rates, general economic conditions, etc.). In addition, changes in interest rates can be sudden and unpredictable, and there is no guarantee that Fund management will anticipate such movement accurately. A Fund may experience losses as a result of movements in interest rates.

Changing interest rates may have unpredictable effects on markets, which may detract from Fund performance. It is uncertain whether rates will remain steady, increase or decrease in the future. As such, the Funds may face a heightened level of risk associated with changing interest rates and/or bond yields. This could be driven by a variety of factors, including but not limited to central bank monetary policies, changing inflation or real growth rates, general economic conditions, increasing bond issuances or reduced market demand for certain types of bonds or bonds generally. Further, while bond markets have steadily grown over time, dealer inventories of corporate bonds are near historic lows in relation to market size. As a result, there has been a significant reduction in the ability of dealers to “make markets”.

Bond funds and individual bonds with a longer duration (a measure used to determine the sensitivity of a security’s price to changes in interest rates) tend to be more sensitive to changes in interest rates, usually making them more volatile than funds or securities with shorter durations. All of the factors mentioned above, individually or collectively, could potentially lead to decreased liquidity and increased volatility in the fixed income markets, or negatively impact a Fund’s performance or cause a Fund to incur losses.

A Fund may enter into opposite sides of multiple interest rate swaps or other derivatives with respect to the same underlying reference instrument (e.g., a 10-year U.S. treasury) that have different effective dates with respect to interest accrual time periods also for the principal purpose of generating distributable gains (characterized as ordinary income for tax purposes) that are not part of a Fund’s duration or yield curve management strategies. In such a “paired swap transaction”, a

Fund would generally enter into one or more interest rate swap agreements whereby a Fund agrees to make regular payments starting at the time a Fund enters into the agreements equal to a floating interest rate in return for payments equal to a fixed interest rate (the “initial leg”). A Fund would also enter into one or more interest rate swap agreements on the same underlying instrument, but take the opposite position (i.e., in this example, a Fund would make regular payments equal to a fixed interest rate in return for receiving payments equal to a floating interest rate) with respect to a contract whereby the payment obligations do not commence until a date following the commencement of the initial leg (the “forward leg”).

A Fund may engage in investment strategies, including those that employ the use of paired swap transactions, the use of interest rate swaps to seek to capitalize on differences between short-term and long-term interest rates and other derivatives transactions, to, among other things, seek to generate current, distributable income, even if such strategies could potentially result in declines in a Fund’s net asset value (“NAV”). A Fund’s income and gain-generating strategies, including certain derivatives strategies, may generate current income and gains taxable as ordinary income sufficient to support monthly distributions even in situations when a Fund has experienced a decline in net assets due to, for example, adverse changes in the broad U.S. or non-U.S. equity markets or a Fund’s debt investments, or arising from its use of derivatives. For instance, a portion of a Fund’s monthly distributions may be sourced from paired swap transactions utilized to produce current distributable ordinary income for tax purposes on the initial leg, with a substantial possibility that a Fund will later realize a corresponding capital loss and potential decline in its NAV with respect to the forward leg (to the extent there are not corresponding offsetting capital gains being generated from other sources). Because some or all of these transactions may generate capital losses without corresponding offsetting capital gains, portions of a Fund’s distributions recognized as ordinary income for tax purposes (such as from paired swap transactions, for example) may be economically similar to a taxable return of capital when considered together with such capital losses. More generally, sales of a Fund’s portfolio holdings may result in short-term capital gains (which are generally taxed to shareholders at ordinary income tax rates when distributed net of short-term capital losses and net of long-term capital losses), potentially subjecting shareholders of a Fund to adverse tax consequences.

Classifications of the Funds’ portfolio holdings in this report are made according to financial reporting standards. The classification of a particular portfolio holding as shown in the Allocation Breakdown and Schedule of Investments or Consolidated Schedule of Investments sections of this report may differ from the classification used for the

Funds’ compliance calculations, including those used in the Funds’ then-current prospectus, investment objectives, regulatory and other investment limitations and policies, which may be based on different asset class, sector or geographical classifications. Each Fund is separately monitored for compliance with respect to prospectus and regulatory requirements.

The geographical classification of foreign securities in this report, if any, is classified by the country of incorporation of a holding. In certain instances, a security’s country of incorporation may be different from its country of economic exposure.

In February 2022, Russia launched an invasion of Ukraine. As a result, Russia and other countries, persons and entities that provided material aid to Russia’s aggression against Ukraine, have been the subject of economic sanctions and import and export controls imposed by countries throughout the world, including the United States. Such measures have had and may continue to have an adverse effect on the Russian, Belarusian and other securities and economies, which may, in turn, negatively impact a Fund. The extent, duration and impact of Russia’s military action in Ukraine, related sanctions and retaliatory actions are difficult to ascertain, but could be significant and have severe adverse effects on the region, including significant adverse effects on the regional, European and global economies and the markets for certain securities and commodities, such as oil and natural gas, as well as other sectors. Further, a Fund may have investments in securities and instruments that are economically tied to the region and may have been negatively impacted by the sanctions and counter-sanctions by Russia, including declines in value and reductions in liquidity. The sanctions may cause a Fund to sell portfolio holdings at a disadvantageous time or price or to continue to hold investments that a Fund may no longer seek to hold. In addition, the armed conflict among the United States, Israel, and Iran has caused, and could continue to cause, significant market disruptions and volatility. The conflict has had a particular negative impact on oil and gas markets, which could have a broader adverse effect on many sectors of the global economy in the future.

The United States’ enforcement of restrictions on U.S. investments in certain issuers and tariffs on goods from certain other countries has contributed to and may continue to contribute to international trade tensions and may impact portfolio securities. The U.S. government has indicated an intent to alter its approach to international trade policy, including in some cases renegotiating, modifying or terminating certain bilateral or multi-lateral trade arrangements with foreign countries, and it has proposed to take and/or taken related actions, including the imposition of or stated potential imposition of a broad range of tariffs. The imposition of tariffs, trade restrictions, currency restrictions or similar actions (or retaliatory measures taken in response) could lead

to, for example, price volatility, reduced market sentiment, and changes in inflation expectations. These and other geopolitical events may contribute to increased instability in the U.S. and global economies and markets, which may have an adverse effect on the performance of a Fund and its investments.

The common shares of the Funds trade on the New York Stock Exchange. As with any stock, the price of a Fund’s common shares will fluctuate with market conditions and other factors. If you sell your common shares of a Fund, the price received may be more or less than your original investment. Shares of management investment companies, such as the Funds, frequently trade at a discount from their NAV and may trade at a price that is less than the initial offering price and/or the NAV of such shares. Further, if a Fund’s shares trade at a price that is more than the initial offering price and/or the NAV of such shares, including at a substantial premium and/or for an extended period of time, there is no assurance that any such premium will be sustained for any period of time and will not decrease, or that the shares will not trade at a discount to NAV thereafter.

Increased volatility in the U.S. and global markets could be harmful to the Funds, issuers in which they invest and other market participants and Fund service providers. For example, if a bank at which a Fund or issuer has an account fails, any cash or other assets in bank or custody accounts, which may be substantial in size, could be temporarily inaccessible or permanently lost by the Fund or issuer. If a bank that provides a subscription line credit facility, asset-based facility, other credit facility and/or other services to an issuer or to a fund fails, the issuer or fund could be unable to draw funds under its credit facilities or obtain replacement credit facilities or other services from other lending institutions with similar terms.

Issuers in which a Fund may invest can be affected by volatility in the banking sector. Even if banks used by issuers in which the Funds invest remain solvent, volatility in the banking sector could contribute to, cause or intensify an economic recession, increase the costs of capital and banking services or result in the issuers being unable to obtain or refinance indebtedness at all or on as favorable terms as could otherwise have been obtained. Conditions in the banking sector are evolving, and the scope of any potential impacts to a Fund and issuers, both from market conditions and also potential legislative or regulatory responses, is uncertain. Such conditions and responses, as well as a changing interest rate environment, can contribute to decreased market liquidity and erode the value of certain holdings. Market volatility and uncertainty and/or a downturn in market and economic and financial conditions, as a result of developments in the banking sector or otherwise (including as a result of delayed access to cash or credit facilities), could have an adverse impact on the Funds and issuers in which they invest.

On each Fund Summary page in this Shareholder Report, the Average Annual Total Return table and Cumulative Returns chart measure performance assuming that any dividend and capital gain distributions were reinvested. Total return is calculated by determining the percentage change in NAV or market price (as applicable) in the specified period. Returns do not reflect the deduction of taxes that a shareholder would pay on Fund distributions. Total return for a period of more than one year represents the average annual total return. Performance at market price will differ from results at NAV. Although market price returns tend to reflect investment results over time, during shorter periods returns at market price can also be influenced by factors such as changing views about a Fund, market conditions, supply and demand for the Fund’s shares, or changes in the Fund’s dividends. Performance shown is net of fees and expenses. Historical NAV performance for a Fund may have been positively impacted by fee waivers or expense limitations in place during some or all of the periods shown, if applicable. Future performance (including total return or yield) and distributions may be negatively impacted by the expiration or reduction of any such fee waivers or expense limitations.

The dividend rate that a Fund pays on its common shares may vary as portfolio and market conditions change, and will depend on a number of factors, including without limit the amount of a Fund’s undistributed net investment income and net short- and long-term capital gains, as well as the costs of any leverage obtained by a Fund. As portfolio and market conditions change, the rate of distributions on the common shares and a Fund’s dividend policy could change. There can be no assurance that a change in market conditions or other factors will not result in a change in a Fund’s distribution rate or that the rate will be sustainable in the future.

The following table discloses the inception date and diversification status of each Fund:

An investment in a Fund is not a bank deposit and is not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency. It is possible to lose money on investments in a Fund.

The Trustees are responsible generally for overseeing the management of the Funds. The Trustees authorize the Funds to enter into service agreements with Pacific Investment Management Company LLC (“PIMCO”) and other service providers in order to provide, and in some

cases authorize service providers to procure through other parties, necessary or desirable services on behalf of the Funds. Shareholders are not parties to or third-party beneficiaries of such service agreements. Neither a Fund’s prospectus or Statement of Additional Information (“SAI”), any press release or shareholder report, any contracts filed as exhibits to a Fund’s registration statement, nor any other communications, disclosure documents or regulatory filings (including this report) from or on behalf of a Fund creates a contract between or among any shareholders of a Fund, on the one hand, and the Fund, a service provider to the Fund, and/or the Trustees or officers of the Fund, on the other hand.

The Trustees (or the Funds and their officers, service providers or other delegates acting under authority of the Trustees) may amend its most recent prospectus or use a new prospectus or SAI with respect to a Fund, adopt and disclose new or amended policies and other changes in press releases and shareholder reports and/or amend, file and/or issue any other communications, disclosure documents or regulatory filings, and may amend or enter into any contracts to which a Fund is a party, and interpret the investment objective(s), policies, restrictions and contractual provisions applicable to any Fund, without shareholder input or approval, except in circumstances in which shareholder approval is specifically required by law (such as changes to fundamental investment policies) or where a shareholder approval requirement was specifically disclosed in a Fund’s then-current prospectus, SAI or shareholder report and is otherwise still in effect.

PIMCO has adopted written proxy voting policies and procedures (“Proxy Policy”) as required by Rule under the Investment Advisers Act of 1940, as amended. The Proxy Policy has been adopted by the Funds as the policies and procedures that PIMCO will use when voting proxies on behalf of the Funds. A description of the policies and procedures that PIMCO uses to vote proxies relating to portfolio securities of each Fund, and information about how each Fund voted proxies relating to portfolio securities held during the most recent twelve-month period ended June 30, are available without charge, upon request, by calling the Funds at (844) on the Funds’ website at www.pimco.com, and on the Securities and Exchange Commission’s (“SEC”) website at www.sec.gov.

The Funds file their complete schedules of portfolio holdings with the SEC for the first and third quarters of each fiscal year as an exhibit to their reports on Form N-PORT. The Funds’ Form N-PORT reports are available to the public on the SEC’s website at www.sec.gov and on PIMCO’s website at www.pimco.com, and upon request by calling PIMCO at (844) In August 2024, the SEC adopted amendments to Form N-PORT requiring funds to file Form N-PORT reports on a monthly basis and within 30 days of month end, with each report being made public 60 days after month end. On April 16, 2025,

the SEC extended the compliance date for Form N-PORT amendments and fund groups with $1 billion or more in net assets will be required to comply with the amendments for reports filed on or after November 17, 2027. On February 18, 2026, the SEC extended the compliance date for Form N-PORT reporting requirements related to Rule 35d-1 (the “Names Rule”) to November 17, 2027 for fund groups with net assets of $10 billion or more.

SEC rules allow the Funds to fulfill their obligation to deliver shareholder reports to investors by providing access to such reports online free of charge and by mailing a notice that the report is electronically available. Investors may elect to receive all future reports in paper free of charge by contacting their financial intermediary or, if invested directly with a Fund, investors can inform the Fund by calling (844) 33-PIMCO. Any election to receive reports in paper will apply to all funds held with the fund complex if invested directly with a Fund or to all funds held in the investor’s account if invested through a financial intermediary. Paper copies of the Funds’ shareholder reports are required to be provided free of charge by the Fund or financial intermediary upon request.

PIMCO Corporate & Income Opportunity Fund

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The following table is intended to assist investors in understanding the fees and expenses (annualized) that an investor in Common Shares of the Fund would bear, directly or indirectly, as a result of an offering. The table reflects the use of leverage attributable to the Fund’s reverse repurchase agreements averaged over the fiscal year ended June 30, 2026 in an amount equal to 17.62% of the Fund’s average total managed assets, including the assets attributable to such leverage (or 21.39% of the Fund’s average total net assets attributable to Common Shares) and shows Fund expenses as a percentage of net assets attributable to Common Shares. The percentages above do not reflect the Fund’s use of other forms of economic leverage, such as credit default swaps or other derivative instruments. The table and example below are based on the Fund’s capital structure as of June 30, 2026. The extent of the Fund’s assets attributable to leverage following an offering, and the Fund’s associated expenses, are likely to vary (perhaps significantly) from these assumptions.

The following example illustrates the expenses that you would pay on a $1,000 investment in Common Shares of the Fund, assuming (1) that the Fund’s net assets do not increase or decrease, (2) that the Fund incurs total annual expenses of 1.52% of net assets attributable to Common Shares in years 1 through 10 (assuming assets attributable to reverse repurchase agreements representing 17.62% of the Fund’s total managed assets) and (3) a 5% annual return:

PIMCO Corporate & Income Strategy Fund

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The following table is intended to assist investors in understanding the fees and expenses (annualized) that an investor in Common Shares of the Fund would bear, directly or indirectly, as a result of an offering. The table reflects the use of leverage attributable to the Fund’s reverse repurchase agreements averaged over the fiscal year ended June 30, 2026 in an amount equal to 14.64% of the Fund’s average total managed assets, including the assets attributable to such leverage (or 17.15% of the Fund’s average total net assets attributable to Common Shares) and shows Fund expenses as a percentage of net assets attributable to Common Shares. The percentages above do not reflect the Fund’s use of other forms of economic leverage, such as credit default swaps or other derivative instruments. The table and example below are based on the Fund’s capital structure as of June 30, 2026. The extent of the Fund’s assets attributable to leverage following an offering, and the Fund’s associated expenses, are likely to vary (perhaps significantly) from these assumptions.

The following example illustrates the expenses that you would pay on a $1,000 investment in Common Shares of the Fund, assuming (1) that the Fund’s net assets do not increase or decrease, (2) that the Fund incurs total annual expenses of 1.53% of net assets attributable to Common Shares in years 1 through 10 (assuming assets attributable to reverse repurchase agreements representing 14.64% of the Fund’s total managed assets) and (3) a 5% annual return:

PIMCO High Income Fund

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The following table is intended to assist investors in understanding the fees and expenses (annualized) that an investor in Common Shares of the Fund would bear, directly or indirectly, as a result of an offering. The table reflects the use of leverage attributable to the Fund’s reverse repurchase agreements averaged over the fiscal year ended June 30, 2026 in an amount equal to 19.97% of the Fund’s average total managed assets, including the assets attributable to such leverage (or 24.95% of the Fund’s average total net assets attributable to Common Shares) and shows Fund expenses as a percentage of net assets attributable to Common Shares. The percentages above do not reflect the Fund’s use of other forms of economic leverage, such as credit default swaps or other derivative instruments. The table and example below are based on the Fund’s capital structure as of June 30, 2026. The extent of the Fund’s assets attributable to leverage following an offering, and the Fund’s associated expenses, are likely to vary (perhaps significantly) from these assumptions.

The following example illustrates the expenses that you would pay on a $1,000 investment in Common Shares of the Fund, assuming (1) that the Fund’s net assets do not increase or decrease, (2) that the Fund incurs total annual expenses of 1.78% of net assets attributable to Common Shares in years 1 through 10 (assuming assets attributable to reverse repurchase agreements representing 19.97% of the Fund’s total managed assets) and (3) a 5% annual return:

PIMCO Income Strategy Fund

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The following table is intended to assist investors in understanding the fees and expenses (annualized) that an investor in Common Shares of the Fund would bear, directly or indirectly, as a result of an offering. The table reflects the use of leverage attributable to the Fund’s reverse repurchase agreements averaged over the fiscal year ended June 30, 2026 in an amount equal to 7.68% of the Fund’s average total managed assets, including the assets attributable to such leverage (or 8.32% of the Fund’s average total net assets attributable to Common Shares) and shows Fund expenses as a percentage of net assets attributable to Common Shares. The percentages above do not reflect the Fund’s use of other forms of economic leverage, such as credit default swaps or other derivative instruments. The table and example below are based on the Fund’s capital structure as of June 30, 2026. The extent of the Fund’s assets attributable to leverage following an offering, and the Fund’s associated expenses, are likely to vary (perhaps significantly) from these assumptions.

The following example illustrates the expenses that you would pay on a $1,000 investment in Common Shares of the Fund, assuming (1) that the Fund’s net assets do not increase or decrease, (2) that the Fund incurs total annual expenses of 1.29% of net assets attributable to Common Shares in years 1 through 10 (assuming assets attributable to reverse repurchase agreements representing 7.68% of the Fund’s total managed assets) and (3) a 5% annual return:

PIMCO Income Strategy Fund II

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