424B3

PIMCO Income Strategy Fund II

(the “Fund”)

Supplement dated June 24, 2026 to the Fund’s Prospectus and Statement of Additional Information, each dated April 24, 2024, and each as supplemented from time to time

(respectively, the “Prospectus” and the “SAI”)

This supplement provides new and additional information beyond that contained in the Prospectus and SAI and should be read in conjunction with the Prospectus and SAI.

Effective immediately, the Prospectus and SAI are revised as follows:

The following paragraph is added after the second full paragraph on page ii of the cover to the Prospectus:

The Fund may invest in and/or originate loans, including, without limitation, residential and/or commercial real estate or mortgage-related loans, consumer loans or other types of loans, which may be in the form of, and without limitation as to a loan’s level of seniority within a capital structure, whole loans, assignments, participations, secured and unsecured notes, senior and second lien loans, mezzanine loans, bridge loans or similar investments, including to borrowers that are unrated or have credit ratings that are determined by one or more nationally recognized statistical rating organizations (“NRSROs”) and/or PIMCO to be below investment grade. The Fund may invest in and/or originate loans to corporations and/or other legal entities and individuals, including

foreign (non-U.S.)

entities and individuals. When acquiring and/or originating loans, the Fund is not restricted by any particular borrower credit criteria. Accordingly, certain loans acquired or originated by the Fund may be subprime in quality, or may become subprime in quality.

The following paragraph is added before the first full paragraph on page 4 in the “Prospectus Summary – Portfolio Contents” section of the Prospectus:

The Fund may invest in and/or originate loans, including, without limitation, residential and/or commercial real estate or mortgage-related loans, consumer loans or other types of loans, which may be in the form of, and without limitation as to a loan’s level of seniority within a capital structure, whole loans, assignments, participations, secured and unsecured notes, senior and second lien loans, mezzanine loans, bridge loans or similar investments, including to borrowers that are unrated or have credit ratings that are determined by one or more NRSROs and/or PIMCO to be below investment grade. The Fund may invest in and/or originate loans to corporations and/or other legal entities and individuals, including

foreign (non-U.S.)

The

sections entitled

“

Loans and Other Indebtedness; Loan Acquisitions, Participations and

Assignments Risk

”

in the

“

Prospectus Summary –Principal Risks of the Fund

”

section of the Prospectus

, and the section entitled

“

Loans and Other Indebtedness; Loan Acquisitions, Participations and

Assignments Risk

”

in the

“

Principal Risks of the Fund

”

section of the Prospectus, are stricken in their entirety and each replaced with the following:

Loans and Other Indebtedness; Loan Acquisitions, Participations and Assignments Risk

Loan interests may take the form of (i) direct interests acquired during a primary distribution or other purchase of a loan, (ii) loans originated by the Fund or (iii) assignments of, novations of or participations in all or a portion of

a loan acquired in secondary markets. In addition to credit risk and interest rate risk, the Fund’s exposure to loan interests may be subject to additional risks. For example, purchasers of loans and other forms of direct indebtedness depend primarily upon the creditworthiness of the borrower for payment of principal and interest. Loans are subject to the risk that scheduled interest or principal payments will not be made in a timely manner or at all, either of which may adversely affect the value of the loan. If the Fund does not receive scheduled interest or principal payments on such indebtedness, the Fund’s share price and yield could be adversely affected. Loans that are fully secured may offer the Fund more protection than an unsecured loan in the event of

non-payment

of scheduled interest or principal if the Fund is able to access and monetize the collateral. However, the collateral underlying a loan, if any, may be unavailable or insufficient to satisfy a borrower’s obligation. If the Fund becomes owner, whole or in part, of any collateral after a loan is foreclosed, the Fund may incur costs associated with owning and/or monetizing its ownership of the collateral.

During periods of deteriorating economic conditions, such as recessions or periods of rising unemployment, or changing interest rates (notably increases), delinquencies and losses generally increase, sometimes dramatically, with respect to obligations under such loans. An economic downturn or individual corporate developments could adversely affect the market for these instruments and reduce the Fund’s ability to sell these instruments at an advantageous time or price. An economic downturn could also lead to a higher

non-payment

rate and, a loan may lose significant market value before a default occurs.

Investments in loans through a purchase of a loan, loan origination or a direct assignment of a financial institution’s interests with respect to a loan may involve additional risks to the Fund. For example, if a loan is foreclosed, the Fund could become owner, in whole or in part, of any collateral, which could include, among other assets, real estate or other real or personal property, and would bear the costs and liabilities associated with owning and holding or disposing of the collateral.

Moreover, the purchaser of an assignment typically succeeds to all the rights and obligations under the loan agreement with the same rights and obligations as the assigning lender. Assignments may, however, be arranged through private negotiations between potential assignees and potential assignors, and the rights and obligations acquired by the purchaser of an assignment may differ from, and be more limited than, those held by the assigning lender. The Fund may also invest in loans that are not secured by collateral which typically present greater risks than collateralized loans.

In connection with purchasing loan participations, the Fund generally will have no right to enforce compliance by the borrower with the terms of the loan agreement relating to the loan, nor any rights of

set-off against

the borrower, and the Fund may not directly benefit from any collateral supporting the loan in which it has purchased the loan participation. As a result, the Fund will be subject to the credit risk of both the borrower and the lender that is selling the participation. In the event of the insolvency of the lender selling a participation, the Fund may be treated as a general creditor of the lender and may not benefit from any

set-off

between the lender and the borrower. Certain loan participations may be structured in a manner designed to prevent purchasers of participations from being subject to the credit risk of the lender, but even under such a structure, in the event of the lender’s insolvency, the lender’s servicing of the participation may be delayed and the assignability of the participation impaired.

The Fund may have difficulty disposing of loans and loan participations. Because there may not be a liquid market for many such investments, the Fund anticipates that such investments could be sold only to a limited number of institutional investors. The lack of a liquid secondary market may have an adverse impact on the value of such investments and the Fund’s ability to dispose of particular loans and loan participations when that would be desirable, including in response to a specific economic event such as a deterioration in the creditworthiness of the borrower. The lack of a liquid secondary market for loans and loan participations also may make it more difficult for the Fund to assign a value to these securities for purposes of valuing the Fund’s portfolio.

Investments in loans may include participations in bridge loans, which are loans taken out by borrowers for a short period (typically less than one year) pending arrangement of more permanent financing through, for example, the issuance of bonds, frequently high yield bonds issued for the purpose of acquisitions.

Investments in loans may include acquisitions of, or participation in, delayed draw and delayed funding loans and revolving credit facilities. These commitments may have the effect of requiring the Fund to increase its investment in a borrower at a time when it might not otherwise decide to do so (including at a time when the company’s financial condition makes it unlikely that such amounts will be repaid). Delayed draw and delayed funding loans and revolving credit facilities may be subject to restrictions on transfer, and only limited opportunities may exist to resell such instruments. As a result, the Fund may be unable to sell such investments at an opportune time or may have to resell them at less than fair market value. Further, the Fund may need to hold liquid assets in order to provide funding for these types of commitments, meaning the Fund may not be able to invest in other attractive investments, or the Fund may need to liquidate existing assets in order to provide such funding.

To the extent the Fund invests in loans, including, but not limited to, bank loans,

non-syndicated

loans, the residual or equity tranches of mortgage-related and other asset-backed securities, which may be referred to as subordinate mortgage-backed or asset-backed securities and interest-only mortgage-backed or asset-backed securities, and other investments, or originates loans, the Fund may be subject to greater levels of credit risk, call risk, settlement risk, risk of subordination to other creditors, insufficient or lack of protection under federal securities laws and liquidity risk. These instruments are considered predominantly speculative with respect to an issuer’s continuing ability to make principal and interest payments and may be more volatile than other types of securities. The Fund may also be subject to greater levels of liquidity risk than funds that do not invest in loans. In addition, the loans in which the Fund invests may not be listed on any exchange and a secondary market for such loans may be comparatively illiquid relative to markets for other more liquid fixed income securities. Consequently, transactions in loans may involve greater costs than transactions in more actively traded securities. In connection with certain loan transactions, transaction costs that are borne by the Fund may include the expenses of third parties that are retained to assist with reviewing and conducting diligence, negotiating, structuring and servicing a loan transaction, and/or providing other services in connection therewith. Furthermore, the Fund may incur such costs in connection with loan transactions that are pursued by the Fund but not ultimately consummated

(so-called

“broken deal costs”). Restrictions on transfers in loan agreements, a lack of publicly-available information, irregular trading activity and wide bid/ask spreads, among other factors, may, in certain circumstances, make loans more difficult to sell at an advantageous time or price than other types of securities or instruments. These factors may result in the Fund being unable to realize full value for the loans and/or may result in the Fund not receiving the proceeds from a sale of a loan for an extended period after such sale, each of which could result in losses to the Fund. Some loans may have extended trade settlement periods, including settlement periods of greater than seven days, which may result in cash not being immediately available to the Fund. If an issuer of a loan prepays or redeems the loan prior to maturity, the Fund may have to reinvest the proceeds in other loans or similar instruments that may pay lower interest rates. Because of such risks involved in investing in loans, an investment in the Fund should be considered speculative.

The Fund’s investments in subordinated and unsecured loans generally are subject to similar risks as those associated with investments in secured loans. Subordinated or unsecured loans are lower in priority of payment to secured loans and are subject to the additional risk that the cash flow of the borrower and property securing the loan or debt, if any, may be insufficient to meet scheduled payments after giving effect to the senior secured obligations of the borrower. This risk is generally higher for subordinated unsecured loans or debt, which are not backed by a security interest in any specific collateral. Subordinated and unsecured loans generally have greater price volatility than secured loans and may be less liquid. There is also a possibility that originators will not be able to sell participations in subordinated or unsecured loans, which would create greater credit risk exposure for the holders of such loans. Subordinate and unsecured loans share the same risks as other below investment grade securities.

There may be less readily available information about most loans and the underlying borrowers than is the case for many other types of securities. Loans may be issued by borrowers that are not subject to SEC reporting requirements and therefore may not be required to file reports with the SEC or may file reports that are not required to comply with SEC form requirements. In addition, such borrowers may be subject to a less stringent liability disclosure regime than companies subject to SEC reporting requirements. Loans may not be considered

“securities,” and purchasers, such as the Fund, therefore may not be entitled to rely on the anti-fraud protections of the federal securities laws. Because there is limited public information available regarding loan investments, the Fund is particularly dependent on the analytical abilities of the Fund’s portfolio managers.

Economic exposure to loan interests through the use of derivative transactions may involve greater risks than if the Fund had invested in the loan interest directly during a primary distribution, through direct originations or through assignments of, novations of or participations in a loan acquired in secondary markets since, in addition to the risks described above, certain derivative transactions may be subject to leverage risk and greater illiquidity risk, counterparty risk, valuation risk and other risks.

The following sections are added after the section entitled “Loans and Other Indebtedness; Loan Acquisitions, Participations and Assignments Risk” in the “Prospectus Summary—Principal Risks of the Fund” section of the Prospectus and after the section entitled “Loans and Other Indebtedness; Loan Acquisitions, Participations and Assignments Risk” in the “Principal Risks of the Fund” section of the Prospectus:

Loan Origination Risk

The Fund may originate loans, including, without limitation, residential and/or commercial real estate or mortgage-related loans, consumer loans or other types of loans, which may be in the form of, and without limitation as to a loan’s level of seniority within a capital structure, whole loans, assignments, participations, secured and unsecured notes, senior and second lien loans, mezzanine loans, bridge loans or similar investments. The Fund may originate loans to corporations and/or other legal entities and individuals, including foreign

(non-U.S.) and

emerging market entities and individuals. Loans may carry significant credit risks (for example, a borrower may not have a credit rating or score or may have a rating or score that indicates significant credit risk). This may include loans to public or private firms or individuals, such as in connection with housing development projects. The loans the Fund invests in or originates may vary in maturity and/or duration. The Fund is not limited in the amount, size or type of loans it may invest in and/or originate, including with respect to a single borrower or with respect to borrowers that are determined to be below investment grade, other than pursuant to any applicable law. The Fund’s investment in or origination of loans may also be limited by the requirements the Fund intends to observe under Subchapter M of the Code in order to qualify as a RIC. The Fund may subsequently offer such investments for sale to third parties; provided, that there is no assurance that the Fund will complete the sale of such an investment. If the Fund is unable to sell, assign or successfully close transactions for the loans that it originates, the Fund will be forced to hold its interest in such loans for an indeterminate period of time. This could result in the Fund’s investments having high exposure to certain borrowers. The Fund will be responsible for the expenses associated with originating a loan (whether or not consummated). This may include significant legal and due diligence expenses, which will be indirectly borne by the Fund and Common Shareholders.

Bridge loans are generally made with the expectation that the borrower will be able to obtain permanent financing in the near future. Any delay in obtaining permanent financing subjects the bridge loan investor to increased risk. A borrower’s use of bridge loans also involves the risk that the borrower may be unable to locate permanent financing to replace the bridge loan, which may impair the borrower’s perceived creditworthiness.

Loan origination and servicing companies are routinely involved in legal proceedings concerning matters that arise in the ordinary course of their business. In addition, a number of participants in the loan origination and servicing industry (including control persons of industry participants) have been the subject of regulatory actions by state regulators, including state attorneys general, and by the federal government. Governmental investigations, examinations or regulatory actions, or private lawsuits, including purported class action lawsuits, may adversely affect such companies’ financial results. To the extent the Fund engages in origination and/or servicing directly, or has a financial interest in, or is otherwise affiliated with, an origination or servicing company, the Fund will be subject to enhanced risks of litigation, regulatory actions and other proceedings. As a result, the Fund may be required to pay legal fees, settlement costs, damages, penalties or other charges, any or all of which could materially adversely affect the Fund and its holdings.

Foreign Loan Originations Risk

The Fund may originate loans to foreign entities and individuals, including foreign

(non-U.S.)

and emerging market entities and individuals. Such loans may involve risks not ordinarily associated with exposure to loans to United States entities and individuals. The foreign lending industry may be subject to less governmental supervision and regulation than exists in the United States; conversely, foreign regulatory regimes applicable to the lending industry may be more complex and more restrictive than those in the United States, resulting in higher costs associated with such investments, and such regulatory regimes may be subject to interpretation or change without prior notice to investors, such as the Fund. Foreign lending may not be subject to accounting, auditing, and financial reporting standards and practices comparable to those in the United States Due to differences in legal systems, there may be difficulty in obtaining or enforcing a court judgment outside the United States In addition, to the extent that investments are made in a limited number of countries, events in those countries will have a more significant impact on the Fund. The Fund’s loans to foreign entities and individuals may be subject to risks of increased transaction costs, potential delays in settlement or unfavorable differences between the U.S. economy and foreign economies.

The Fund’s exposure to loans to foreign entities and individuals may be subject to withholding and other foreign taxes, which may adversely affect the net return on such investments. In addition, fluctuations in foreign currency exchange rates and exchange controls may adversely affect the market value of the Fund’s exposure to loans to foreign entities and individuals. The Fund is unlikely to be able to pass through to its shareholders foreign income tax credits in respect of any foreign income taxes it pays.

The following paragraph is added after the second full paragraph on page 38 in the “Portfolio Contents” section of the Prospectus:

foreign (non-U.S.)

entities and individuals. The loans the Fund invests in or originates may vary in maturity and/or duration. The Fund is not limited in the amount, size or type of loans it may invest in and/or originate, including with respect to a single borrower or with respect to borrowers that are determined to be below investment grade, other than pursuant to any applicable law. The Fund’s investment in or origination of loans may also be limited by the requirements the Fund intends to observe under Subchapter M of the Code in order to qualify as a RIC. When acquiring and/or originating loans, the Fund is not restricted by any particular borrower credit criteria. Accordingly, certain loans acquired or originated by the Fund may be subprime in quality, or may become subprime in quality.

The section entitled “Portfolio Contents—Loans and Other Indebtedness; Loan Acquisitions, Participations and Assignments” in the Prospectus is stricken in its entirety and replaced with the following:

Loans and Other Indebtedness; Loan Acquisitions, Participations and Assignments

borrower, and generally are offered by banks or other financial institutions or lending syndicates. The Fund may participate in such syndications, or can buy all or part of a loan, becoming a part lender. When purchasing indebtedness and loan participations, the Fund assumes the credit risk associated with the borrower and may assume the credit risk associated with an interposed bank or other financial intermediary. The indebtedness and loan participations that the Fund may acquire may not be rated by any NRSRO.

A financial institution’s employment as agent bank might be terminated in the event that it fails to observe a requisite standard of care or becomes insolvent. A successor agent bank would generally be appointed to replace the terminated agent bank, and assets held by the agent bank under the loan agreement should remain available to holders of such indebtedness. However, if assets held by the agent bank for the benefit of the Fund were determined to be subject to the claims of the agent bank’s general creditors, the Fund might incur certain costs and delays in realizing payment on a loan or loan participation and could suffer a loss of up to its entire investment, including principal and/or interest. In situations involving other interposed financial institutions (e.g., an insurance company or governmental agency) similar risks may arise.

Purchasers of loans and other forms of direct indebtedness depend primarily upon the creditworthiness of the borrower for payment of principal and interest. Loans are subject to the risk that scheduled interest or principal payments will not be made in a timely manner or at all, either of which may adversely affect the values of the loan. If the Fund does not receive scheduled interest or principal payments on such indebtedness, yield could be adversely affected. Loans that are fully secured may offer the Fund more protection than an unsecured loan in the event of

non-payment

of scheduled interest or principal if the Fund is able to access and monetize the collateral. However, the collateral underlying a loan, if any, may be unavailable or insufficient to satisfy a borrower’s obligation. In the event of the bankruptcy of a borrower, the Fund could experience delays or limitations in its ability to realize the benefits of any collateral securing a loan.

The Fund may acquire loans and loan participations, or originate loans with credit quality comparable to that of issuers of its securities investments. Indebtedness of borrowers whose creditworthiness is poor and/or subprime in quality involves substantially greater risks, and may be highly speculative. Some borrowers may never pay off their indebtedness, or may pay only a small fraction of the amount owed.

Consequently, when acquiring indebtedness of borrowers with poor credit, the Fund bears a substantial risk of losing the entire amount invested. The Fund may make purchases of indebtedness and loan participations to achieve income and/or capital appreciation, rather than to seek income.

The Fund limits the amount of its total assets that it will invest in issuers within the same industry. For purposes of this limit, the Fund generally will treat the borrower as the “issuer” of indebtedness held by the Fund. In the case of loan participations where a bank or other lending institution serves as a financial intermediary between the Fund and the borrower, if the participation does not shift to the Fund the direct debtor-creditor relationship with the borrower, the Fund will treat both the lending bank or other lending institution and the borrower as “issuers.” Treating a financial intermediary as an issuer of indebtedness may restrict the Fund’s ability to invest in indebtedness related to a single financial intermediary, or a group of intermediaries engaged in the same industry, even if the underlying borrowers represent many different companies and industries.

Loans and other types of direct indebtedness (which the Fund acquires or otherwise gains exposure to) may not be readily marketable and may be subject to restrictions on resale. In connection with certain loan transactions, transaction costs that are borne by the Fund may include the expenses of third parties that are retained to assist with reviewing and conducting diligence, negotiating, structuring and servicing a loan transactions, and/or

providing other services in connection therewith. Furthermore, the Fund may incur such costs in connection with loan transactions that are pursued by the Fund but not ultimately consummated

(so-called

“broken deal costs”). In some cases, negotiations involved in disposing of indebtedness may require weeks to complete.

Consequently, some indebtedness may be difficult or impossible to dispose of readily at what the Investment Manager believes to be a fair price. In addition, valuation of illiquid indebtedness involves a greater degree of judgment in determining the Fund’s NAV than if that value were based on available market quotations, and could result in significant variations in the Fund’s daily share price. At the same time, some loan interests are traded among certain financial institutions and accordingly may be deemed liquid. As the market for different types of indebtedness develops, the liquidity of these instruments may improve. Investments in loan participations are considered to be debt obligations for purposes of the Fund’s investment restriction relating to the lending of funds or assets.

In purchasing loans, the Fund will compete with a broad spectrum of lenders. Increased competition for, or a diminishment in the available supply of, qualifying loans could result in lower yields on such loans, which could reduce Fund performance. Investments in loans through a purchase of a loan, loan origination or direct assignment of a financial institution’s interests with respect to a loan may involve additional risks to the Fund. The purchaser of an assignment typically succeeds to all the rights and obligations under the loan agreement with the same rights and obligations as the assigning lender. Assignments may, however, be arranged through private negotiations between potential assignees and potential assignors, and the rights and obligations acquired by the purchaser of an assignment may differ from, and be more limited than, those held by the assigning lender. For example, if a loan is foreclosed, the Fund could become owner, in whole or in part, of any collateral, and would bear the costs and liabilities associated with owning and holding or disposing of the collateral. In addition, it is conceivable that under emerging legal theories of lender liability, the Fund could be held liable. It is unclear whether loans and other forms of direct indebtedness offer securities law protections against fraud and misrepresentation. In the absence of definitive regulatory guidance, the Fund relies on the Investment Manager’s research in an attempt to avoid situations where fraud or misrepresentation could adversely affect the Fund.

For whole loans purchased by the Fund (which would not include, for example, underlying loans in a securitized product held by the Fund), it is expected that a qualified custodian of the Fund will typically receive or be provided with access to an executed loan package. While the executed packages may differ for certain investments, it is typically comprised of evidence in the form of a promissory note or similar document, an executed copy of the underlying loan agreement or security instrument, and an executed copy of the loan assignment. Although the Fund’s custodian would have access to loan files, whether in electronic form or otherwise, it is expected that the enforcement of the loans will generally be handled by the loan servicer.

The Fund

may invest in debtor-in-possession

financings (commonly known as “DIP financings”). DIP financings are arranged when an entity seeks the protections of the bankruptcy court under Chapter 11 of the U.S. Bankruptcy Code. These financings allow the entity to continue its business operations while reorganizing under Chapter 11. Such financings constitute senior liens on unencumbered security (i.e., security not subject to other creditors’ claims). There is a risk that the entity will not emerge from Chapter 11 and be forced to liquidate its assets under Chapter 7 of the U.S. Bankruptcy Code. In the event of liquidation, the Fund’s only recourse will be against the property securing the DIP financing.

The following section is added after the section entitled “Portfolio Contents—Loans and Other Indebtedness; Loan Acquisitions, Participations and Assignments” in the Prospectus:

Loan Origination

(non-U.S.)

entities and individuals. Such borrowers may have credit ratings that are

determined by one or more NRSROs or PIMCO to be below investment grade. The loans the Fund originates may vary in maturity and/or duration. The Fund is not limited in the amount, size or type of loans it may originate, including with respect to a single borrower or with respect to borrowers that are determined to be below investment grade, other than pursuant to any applicable law. The Fund’s origination of loans may also be limited by the Fund’s intention to continue to qualify as a RIC. The Fund will retain all fees received in connection with originating or structuring the terms of any such loan.

The Fund may make investments in debt instruments and other securities directly or through one or more wholly owned and controlled subsidiaries formed by the Fund. References herein to the Fund include references to a wholly owned and controlled subsidiary in respect of the Fund’s investment exposure. The Fund will treat a wholly owned and controlled subsidiary’s assets as assets of the Fund for purposes of determining compliance with various provisions of the 1940 Act applicable to the Fund, including those relating to investment policies (Section 8), capital structure and leverage (Section 18) and affiliated transactions and custody (Section 17).

In determining whether to make a direct loan, the Fund will rely primarily upon the creditworthiness of the borrower and/or any collateral for payment of interest and repayment of principal. In making a direct loan, the Fund is exposed to the risk that the borrower may default or become insolvent and, consequently, that the Fund will lose money on the loan. Furthermore, direct loans may subject the Fund to liquidity and interest rate risk and certain direct loans may be deemed illiquid. Direct loans are not publicly traded and may not have a secondary market. The lack of a secondary market for direct loans may have an adverse impact on the ability of the Fund to dispose of a direct loan and/or to value the direct loan.

When engaging in direct lending, the Fund’s performance may depend, in part, on the ability of the Fund to originate loans on advantageous terms. In originating and purchasing loans, the Fund will often compete with a broad spectrum of lenders. Increased competition for, or a diminishment in the available supply of, qualifying loans could result in lower yields on and/or less advantageous terms of such loans, which could reduce Fund performance.

As part of its lending activities, the Fund may originate loans (including subprime loans) to borrowers that are experiencing significant financial or business difficulties, including borrowers involved in bankruptcy or other reorganization and liquidation proceedings or that are rated ”below investment grade” by an NRSRO or unrated. Although the terms of such financing may result in significant financial returns to the Fund, they involve a substantial degree of risk. The level of analytical sophistication, both financial and legal, necessary for successful financing to borrowers experiencing significant business and financial difficulties is unusually high. Different types of assets may be used as collateral for the Fund’s loans and, accordingly, the valuation of and risks associated with such collateral will vary by loan. There is no assurance that the Fund will correctly evaluate the value of the assets collateralizing the Fund’s loans or the prospects for a successful reorganization or similar action. In any reorganization or liquidation proceeding relating to a borrower that the Fund funds, the Fund may lose all or part of the amounts advanced to the borrower or may be required to accept collateral with a value less than the amount of the loan advanced by the Fund or its affiliates to the borrower. Furthermore, in the event of a default by a borrower, the Fund may have difficulty disposing of the assets used as collateral for a loan.

Bridge loans are short-term loan arrangements (e.g., 12 to 18 months) typically made by a borrower in anticipation of intermediate-term or long-term permanent financing. Most bridge loans are structured as floating-rate debt with

step-up

provisions under which the interest rate on the bridge loan rises over time. Thus, the longer the loan remains outstanding, the more the interest rate increases. In addition, bridge loans commonly contain a conversion feature that allows the bridge loan investor to convert its loan interest into senior exchange notes if the loan has not been prepaid in full on or prior to its maturity date.

Bridge loans may be subordinate to other debt and may be secured or unsecured. Like any loan, bridge loans involve credit risk. Bridge loans are generally made with the expectation that the borrower will be able to obtain permanent financing in the near future. Any delay in obtaining permanent financing subjects the bridge loan

investor to increased risk. A borrower’s use of bridge loans also involves the risk that the borrower may be unable to locate permanent financing to replace the bridge loan, which may impair the borrower’s perceived creditworthiness.

Various state licensing requirements could apply to the Fund with respect to the origination, acquisition, holding, servicing, foreclosure and/or disposition of, loans and similar assets. The licensing requirements could apply depending on the location of the borrower, the location of the collateral securing the loan, or the location where the Fund or PIMCO operates or has offices. In states in which it is licensed, the Fund or PIMCO will be required to comply with applicable laws and regulations, including consumer protection and anti-fraud laws, which could impose restrictions on the Fund’s or PIMCO’s ability to take certain actions to protect the value of its holdings in such assets and impose compliance costs. Failure to comply with such laws and regulations could lead to, among other penalties, a loss of the Fund’s or PIMCO’s license, which in turn could require the Fund to divest assets located in or secured by real property located in that state. These risks will also apply to issuers and entities in which the Fund invests that hold similar assets, as well as any origination company or servicer in which the Fund owns an interest. Loan origination and servicing companies are routinely involved in legal proceedings concerning matters that arise in the ordinary course of their business. These legal proceedings range from actions involving a single plaintiff to class action lawsuits with potentially tens of thousands of class members. In addition, a number of participants in the loan origination and servicing industry (including control persons of industry participants) have been the subject of regulatory actions by state regulators, including state attorneys general, and by the federal government. Governmental investigations, examinations or regulatory actions, or private lawsuits, including purported class action lawsuits, may adversely affect such companies’ financial results. To the extent the Fund seeks to engage in origination and/or servicing directly, or has a financial interest in, or is otherwise affiliated with, an origination or servicing company, the Fund will be subject to enhanced risks of litigation, regulatory actions and other proceedings. As a result, the Fund may be required to pay legal fees, settlement costs, damages, penalties or other charges, any or all of which could materially adversely affect the Fund and its holdings.

The fourth paragraph of the “Management of the Fund—Investment Management Agreement” section of the Prospectus is hereby amended to read:

The Fund (and not PIMCO) will be responsible for certain fees and expenses that are not covered by the unified fee under the Investment Management Agreement. These include fees and expenses, including travel expenses, and fees and expenses of legal counsel retained for their benefit, of Trustees who are not officers, employees, partners, shareholders or members of PIMCO or its subsidiaries or affiliates; the salaries and other compensation or expenses, including travel expenses, of any of the Fund’s executive officers and employees, if any, who are not officers, directors, shareholders, members, partners or employees of PIMCO or its subsidiaries or affiliates; taxes and governmental fees, if any, levied against the Fund; brokerage fees and commissions, any costs associated with originating loans, and other portfolio transaction expenses incurred by or for the Fund (including, without limitation, fees and expenses of outside legal counsel or third-party consultants retained in connection with reviewing, negotiating and structuring specialized loans and other investments made by the Fund, and subject to specific or general authorization by the Fund’s Board of Trustees (for example,

so-called

respect to share offerings following the Fund’s initial offering, such as rights and shelf offerings (including expenses associated with offerings made pursuant to this prospectus), and expenses associated with tender offers and other share repurchases and redemptions; extraordinary expenses, including extraordinary legal expenses as may arise, including expenses incurred in connection with litigation, proceedings, other claims, and the legal obligations of the Fund to indemnify its Trustees, officers, employees, shareholders, distributors, and agents with respect thereto; and expenses of the Fund which are capitalized in accordance with generally accepted accounting principles.

The section entitled “Investment Objectives and Polices – Loans and Other Indebtedness; Loan Acquisitions, Participations and Assignments” within the SAI is stricken in its entirety and replaced with the following:

Loans and Other Indebtedness; Loan Acquisitions, Participations and Assignments

The Fund may purchase indebtedness and participations in loans held and/or originated by private financial institutions, including commercial and residential mortgage loans, corporate loans and consumer loans, as well as interests and/or servicing or similar rights in such loans. Such instruments may be secured or unsecured and may be newly-originated (and may be specifically designed for the Fund). Indebtedness is different from traditional debt securities in that debt securities are part of a large issue of securities to the public whereas indebtedness may not be a security and may represent a specific commercial loan to a borrower. Loan participations typically represent direct participation, together with other parties, in a loan to a borrower, and generally are offered by banks or other financial institutions or lending syndicates. The Fund may participate in such syndications, or can buy part or all of a loan. When purchasing indebtedness and loan participations, the Fund assumes the credit risk associated with the corporate borrower and may assume the credit risk associated with an interposed bank or other financial intermediary. The indebtedness and loan participations that the Fund may acquire may not be rated by any NRSROs.

A loan is often administered by an agent bank acting as agent for all holders. The agent bank administers the terms of the loan, as specified in the loan agreement. In addition, the agent bank is normally responsible for the collection of principal and interest payments from the corporate borrower and the apportionment of these payments to the credit of all institutions which are parties to the loan agreement. Unless, under the terms of the loan or other indebtedness, the Fund has direct recourse against the corporate borrower, the Fund may have to rely on the agent bank or other financial intermediary to apply appropriate credit remedies against a borrower. This may subject the Fund to delays, expenses and risks that are greater than those that would be involved if the Fund could enforce its rights directly against the borrower. Also, in the event of the insolvency of the lender or interposed bank or other financial intermediary who sold the participation interest to the Fund, the Fund may not have any exclusive or senior claim with respect to the lender’s interest in the corporate loan, or in the collateral securing the corporate loan. If the Fund has purchased the whole loan, the Fund would assume all of the rights of the lender in a commercial loan, including the right to receive payments of principal and interest and other amounts directly from the borrower and to enforce its rights as a lender directly against the borrower.

A financial institution’s employment as agent bank might be terminated in the event that it fails to observe a requisite standard of care or becomes insolvent. A successor agent bank would generally be appointed to replace the terminated agent bank, and assets held by the agent bank under the loan agreement would likely remain available to holders of such indebtedness. However, if assets held by the agent bank for the benefit of the Fund were determined to be subject to the claims of the agent bank’s general creditors, the Fund might incur certain costs and delays in realizing payment on a loan or loan participation and could suffer a loss of principal and/or interest. In situations involving other interposed financial institutions (e.g., an insurance company or governmental agency) similar risks may arise.

Purchasers of loans and other forms of direct indebtedness depend primarily upon the creditworthiness of the borrower for payment of principal and interest. If the Fund does not receive scheduled interest or principal payments on such indebtedness, the Fund’s share price and/or yield of the Common Shares could be adversely affected. Loans that are fully secured offer the Fund more protection than an unsecured loan in the event of

non-payment

of scheduled interest or principal. However, there is no assurance that the liquidation of collateral from a secured loan would satisfy the borrower’s obligation, or that the collateral can be liquidated. In the event of the bankruptcy of a borrower, the Fund could experience delays or limitations in its ability to realize the benefits of any collateral securing a loan.

The Fund may acquire loans and loan participations with credit quality comparable to that of issuers of its securities investments. Indebtedness of companies whose creditworthiness is poor and/or subprime in quality involves substantially greater risks, and may be highly speculative. Some companies may never pay off their indebtedness, or may pay only a small fraction of the amount owed. Consequently, when acquiring indebtedness of companies with poor credit, the Fund bears a substantial risk of losing the entire amount of the instrument acquired. The Fund may make purchases of indebtedness and loan participations to achieve income and/or capital appreciation. Because the Fund establishes a direct contractual relationship with the lender or participant, the Fund is subject to the credit risk of the lender or participant in addition to the usual credit risk of the borrower and any agent bank. Under normal market conditions, loan participations that sell at a discount to the secondary loan price may indicate the borrower has credit problems or other issues associated with the credit risk of the loan. To the extent the credit problems are not resolved, loan participations may not appreciate in value.

The Fund will limit the amount of its total assets that it will invest in any one issuer and the Fund will limit the amount of its total assets that it will invest in issuers within the same industry. For purposes of this limit, the Fund generally will treat the corporate borrower as the “issuer” of indebtedness held by the Fund. In the case of loan participations where a bank or other lending institution serves as a financial intermediary between the Fund and the borrower, if the participation does not shift to the Fund the direct debtor-creditor relationship with the borrower, SEC interpretations require the Fund to treat both the lending bank or other lending institution and the borrower as ”issuers.” Treating a financial intermediary as an issuer of indebtedness may restrict the Fund’s ability to invest in indebtedness related to a single financial intermediary, or a group of intermediaries engaged in the same industry, even if the underlying borrowers represent many different companies and industries.

Loans and other types of direct indebtedness (which the Fund may purchase or otherwise gain exposure to) may not be readily marketable and may be subject to restrictions on resale. A secondary market in corporate loans may be subject to irregular trading activity, wide bid/ask spreads and extended trade settlement periods, which may impair the ability to accurately value existing and prospective investments and to realize in a timely fashion the full value on sale of a corporate loan. In connection with certain loan transactions, transaction costs that are borne by the Fund may include the expenses of third parties that are retained to assist with reviewing and conducting due diligence, negotiating, structuring and servicing a loan transaction, and/or providing other services in connection therewith. Furthermore, the Fund may incur such costs in connection with loan transactions that are pursued by the Fund but not ultimately consummated

(so-called

“broken deal costs”). In some cases, negotiations involved in disposing of indebtedness may require weeks to complete. Consequently, some indebtedness may be difficult or impossible to dispose of readily at what PIMCO believes to be a fair price. In addition, valuation of illiquid indebtedness involves a greater degree of judgment in determining the Fund’s net asset value than if that value were based on available market quotations, and could result in significant variations in the Fund’s daily share price. At the same time, some loan interests are traded among certain financial institutions and accordingly may be deemed liquid. As the market for different types of indebtedness develops, the liquidity of these instruments may improve. Acquisitions of loan participations are considered to be debt obligations for purposes of the Fund’s investment restriction relating to the lending of funds or assets by the Fund.

Investments in loans through a purchase of a loan or a direct assignment of a financial institution’s interests with respect to a loan may involve additional risks to the Fund. The purchaser of an assignment typically succeeds to all the rights and obligations under the loan agreement with the same rights and obligations as the assigning lender. Assignments may, however, be arranged through private negotiations between potential

assignees and potential assignors, and the rights and obligations acquired by the purchaser of an assignment may differ from, and be more limited than, those held by the assigning lender. For example, if a loan is foreclosed, the Fund could become owner, in whole or in part, of any collateral, which could include, among other assets, real estate or other real or personal property, and would bear the costs and liabilities associated with owning and holding or disposing of the collateral (see ”Real Estate Assets and Related Derivatives” above). In addition, it is conceivable that under emerging legal theories of lender liability, the Fund could be held liable as

co-lender.

It is unclear whether loans and other forms of direct indebtedness offer securities law protections against fraud and misrepresentation. In the absence of definitive regulatory guidance, the Fund relies on the Investment Manager’s research in an attempt to avoid situations where fraud or misrepresentation could adversely affect the Fund.

The Fund may make, participate in or acquire

debtor-in-possession

financings (commonly known as “DIP financings”). DIP financings are arranged when an entity seeks the protections of the bankruptcy court under Chapter 11 of the U.S. Bankruptcy Code (“Chapter 11”). These financings allow the entity to continue its business operations while reorganizing under Chapter 11. Such financings constitute senior liens on unencumbered security (i.e., security not subject to other creditors’ claims). There is a risk that the entity will not emerge from Chapter 11 and be forced to liquidate its assets under Chapter 7 of the U.S. Bankruptcy Code. In the event of liquidation, the Fund’s only recourse will be against the property securing the DIP financing.

The Fund may acquire residential mortgage loans and unsecured consumer loans through direct or indirect fully-owned Subsidiaries (each, a “Subsidiary” and collectively, the “Subsidiaries”). The Subsidiaries directly holding a beneficial interest in loans will be formed as domestic common law or statutory trusts with a federally chartered bank serving as trustee. Each such fully-owned Subsidiary trust will hold the beneficial interests of loans and the federally chartered bank acting as trustee will hold legal title to the loans for the benefit of the Subsidiary trust and/or the trust’s beneficial owners (i.e., the Fund or its direct or indirect fully-owned Subsidiary). State licensing laws typically exempt federally chartered banks from their licensing requirements, and federally chartered banks may also benefit from federal preemption of state laws, including any licensing requirements. The use of common law or statutory trusts with a federally chartered bank serving as trustee is intended to address any state licensing requirements that may be applicable to purchasers or holders of loans, including state licensing requirements related to foreclosure. The Fund believes that such direct or indirect fully-owned Subsidiary trusts will not be treated as associations or publicly traded partnerships taxable as corporations for U.S. federal income tax purposes, and that therefore, the Subsidiary trusts will not be subject to U.S. federal income tax at the Subsidiary level. Investments in residential mortgage loans or unsecured consumer loans through entities that are not so treated can potentially be limited by the Fund’s intention to qualify as a RIC under Subchapter M of the Code, and limit the Fund’s ability to qualify as such.

If the Fund or its direct or indirect fully-owned Subsidiary trust is required to be licensed in any particular jurisdiction in order to originate, acquire, hold, dispose or foreclose loans, obtaining the required license may not be viable (because, for example, it is not possible or practical) and the Fund or its Subsidiary trust may be unable to restructure its holdings to address the licensing requirement. In that case, the Fund or its Subsidiary trust may be forced to cease activities involving the affected loans, or may be forced to sell such loans. If a state regulator or court were to determine that the Fund or its Subsidiary trust acquired, held or foreclosed a loan without a required state license, the Fund or its Subsidiary trust could be subject to penalties or other sanctions, prohibited or restricted in its ability to enforce its rights under the loan, or subject to litigation risk or other losses or damages.

Investments in loans may include unfunded loan commitments, which are contractual obligations for future funding. Unfunded loan commitments may include revolving credit facilities, which may obligate the Fund to supply additional cash to the borrower on demand. Unfunded loan commitments represent a future obligation in full, even though a percentage of the committed amount may not be utilized by the borrower. When investing in a loan participation, the Fund has the right to receive payments of principal, interest and any fees to which it is entitled only from the agent selling the loan agreement and only upon receipt of payments by the agent from the borrower. The Fund may receive a commitment fee based on the undrawn portion of the underlying line of credit portion of a loan. In certain circumstances, the Fund may receive a penalty fee upon the prepayment of a loan by a borrower.

Some lending platforms (or their affiliates) may attempt to take advantage of policies in certain states that allow lenders to make loans at advantageous interest rates by incorporating choice of law provisions into loan agreements that hold that the agreements are to be governed by the laws of those lender-friendly states. In the event that a borrower or state regulator successfully invalidates such

choice-of-law

clause, platforms (of their affiliates) may not be able to collect some or all of the interest and principal due on such loans, such loans may not be found to be enforceable or the platforms (or their affiliates) could become subject to penalties and damages. Other platforms may engage in arrangements with funding banks where the platform assists the bank in originating loans that are funded by the bank. In some cases, the loans are sold to the platforms and the platforms as assignees of the bank under applicable law and precedent utilize the bank’s rate and fee exportation authority. At least one federal circuit court has cast doubt upon this theory and other litigation challenges the ability of assignees to utilize a bank’s exportation authority as an assignee of the bank’s loans.

10.

The following section is added after the “Investment Objectives and Polices – Loans and Other Indebtedness; Loan Acquisitions, Participations and Assignments” section of the SAI:

Loan Origination

The Fund may also seek to originate loans, including, without limitation, residential and/or commercial real estate or mortgage-related loans, consumer loans or other types of loans, which may be in the form of, and without limitation as to a loan’s level of seniority within a capital structure, whole loans, assignments, participations, secured and unsecured notes, senior and second lien loans, mezzanine loans, bridge loans or similar investments, including to borrowers that are unrated or have credit ratings that are determined by one or more NRSROs and/or PIMCO to be below investment grade. The Fund may invest in and/or originate loans to corporations and/or other legal entities and individuals, including

foreign (non-U.S.)

entities and individuals. The loans the Fund invests in and/or originates may vary in maturity and/or duration. The Fund is not limited in the amount, size or type of loans it may invest in and/or originate, including with respect to a single borrower or with respect to borrowers that are determined to be below investment grade, other than pursuant to any applicable law. The Fund’s investments in and/or origination of loans may also be limited by the Fund’s intention to continue to qualify as a regulated investment company (“RIC”). The Fund may subsequently offer such investments for sale to third parties; provided, that there is no assurance that the Fund will complete the sale of such an investment. If the Fund is unable to sell, assign or successfully close transactions for the loans that it originates, the Fund will be forced to hold its interest in such loans for an indeterminate period of time. This could result in the Fund’s investments having high exposure to certain borrowers. The Fund will be responsible for the expenses associated with originating a loan (whether or not consummated). This may include significant legal and due diligence expenses, which will be indirectly borne by the Fund and Common Shareholders.

Direct loans between the Fund and a borrower may not be administered by an underwriter or agent bank. The Fund may provide financing to borrowers directly or through companies acquired (or created) and owned by or otherwise affiliated with the Fund. The terms of the direct loans, including the duration of the loan, are negotiated with borrowers in private transactions and the Fund is not limited in the size of loans it may originate, including with respect to a single borrower, other than pursuant to any applicable law. A direct loan may be secured or unsecured. The Fund will retain all fees received in connection with originating or structuring the terms of any such investment.

broad spectrum of lenders. Increased competition for, or a diminishment in the available supply of, qualifying loans could result in lower yields on and/or less advantageous terms of such loans, which could reduce Fund performance.

As part of its lending activities, the Fund may originate loans to companies that are experiencing significant financial or business difficulties, including companies involved in bankruptcy or other reorganization and liquidation proceedings or that are rated “below investment grade” by a national recognized ratings agency. Although the terms of such financing may result in significant financial returns to the Fund, they involve a substantial degree of risk. The level of analytical sophistication, both financial and legal, necessary for successful financing to companies experiencing significant business and financial difficulties is unusually high. Different types of assets may be used as collateral for the Fund’s loans and, accordingly, the valuation of and risks associated with such collateral will vary by loan. There is no assurance that the Fund will correctly evaluate the value of the assets collateralizing the Fund’s loans or the prospects for a successful repayment or a successful reorganization or similar action. In any reorganization or liquidation proceeding relating to a company that the Fund funds, the Fund may lose all or part of the amounts advanced to the borrower or may be required to accept collateral with a value less than the amount of the loan advanced by the Fund or its affiliates to the borrower. Furthermore, in the event of a default by a borrower, the Fund may have difficulty disposing of the assets used as collateral for a loan.

Various state licensing requirements could apply to the Fund with respect to the origination, acquisition, holding, servicing, foreclosure and/or disposition of loans and similar assets. The licensing requirements could apply depending on the location of the borrower, the location of the collateral securing the loan, or the location where the Fund or PIMCO operates or has offices. In states in which it is licensed, the Fund or PIMCO will be required to comply with applicable laws and regulations, including consumer protection and anti-fraud laws, which could impose restrictions on the Fund’s or PIMCO’s ability to take certain actions to protect the value of its holdings in such assets and impose compliance costs. Failure to comply with such laws and regulations could lead to, among other penalties, a loss of the Fund’s or PIMCO’s license, which in turn could require the Fund to divest assets located in or secured by real property located in that state. These risks will also apply to issuers and entities in which the Fund invests that hold similar assets, as well as any origination company or servicer in which the Fund owns an interest.

In addition to laws governing the activities of lenders and servicers, certain states may require, or may in the future require, purchasers or holders of certain loans, including residential mortgage loans and unsecured consumer loans, to be licensed or registered in order to purchase, hold or foreclose such loans, or, in certain states, to collect a rate of interest above a specified rate. To the extent required or determined to be necessary or advisable by the Fund, the Fund will take appropriate steps intended to address any applicable state licensing requirements, which may include acquiring and holding such loans through structures designed to preempt state licensing laws, in order to pursue its objective and strategies. To the extent the Fund (or its direct or indirect

fully-owned Subsidiary) obtains licenses or is required to comply with related regulatory requirements, the Fund could be subject to increased costs and regulatory oversight by governmental authorities, which may have an adverse effect on its results or operations.

11.

The fifth paragraph of the “Investment Manager—Investment Management Agreement” section of the SAI is hereby amended to read:

The Fund (and not PIMCO) will be responsible for certain fees and expenses that are not covered by the unified fee under the Investment Management Agreement. These include fees and expenses, including travel expenses, and fees and expenses of legal counsel retained for their benefit, of Trustees who are not officers, employees, partners, shareholders or members of PIMCO or its subsidiaries or affiliates; the salaries and other compensation or expenses, including travel expenses, of the Fund’s executive officers and employees, if any, who are not officers, directors, shareholders, members, partners or employees of PIMCO or its subsidiaries or affiliates; taxes and governmental fees, if any, levied against the Fund; brokerage fees and commissions, any costs associated with originating loans, and other portfolio transaction expenses incurred by or for the Fund (including, without limitation, fees and expenses of outside legal counsel or third-party consultants retained in connection with reviewing, negotiating and structuring specialized loans and other investments made by the Fund, subject to specific or general authorization by the Board (for example,

so-called

“broken-deal costs” (e.g., fees, costs, expenses and liabilities, including, for example, due diligence-related fees, costs, expenses and liabilities, with respect to unconsummated investments))); expenses of the Fund’s securities lending (if any), including any securities lending agent fees, as governed by a separate securities lending agreement; costs, including interest expenses, of borrowing money or engaging in other types of leverage financing, including, without limitation, through the use by the Fund of reverse repurchase agreements, tender option bonds, bank borrowings and credit facilities; costs, including dividend cost and/or interest expenses and other costs (including, without limitation, offering and related legal costs, fees to brokers, fees to auction agents, fees to transfer agents, fees to ratings agencies and fees to auditors associated with satisfying ratings agency requirements for preferred shares or other securities issued by the Fund and other related requirements in the Fund’s organizational documents) associated with the Fund’s issuance, offering, redemption and maintenance of preferred shares, commercial paper or other senior securities for the purpose of incurring leverage; fees and expenses of any underlying funds or other pooled vehicles in which the Fund invests; dividend and interest expenses on short positions taken by the Fund; organizational and offering expenses of the Fund, including with respect to share offerings following the Fund’s initial offering, such as rights and shelf offerings (including expenses associated with offerings made pursuant to the Prospectus), and expenses associated with tender offers and other share repurchases and redemptions; extraordinary expenses including extraordinary legal expenses as may arise, including expenses incurred in connection with litigation, proceedings, other claims, and the legal obligations of the Fund to indemnify its Trustees, officers, employees, shareholders, distributors, and agents with respect thereto; and expenses of the Fund which are capitalized in accordance with generally accepted accounting principles.

12.

The following subsection is added to the “Taxation” section of the SAI following the subsection entitled “Catastrophe Bonds:”

Loan Origination

Income and gains from certain of the Fund’s activities, including fees received in connection with the origination of loans, may not constitute qualifying income to a RIC for purposes of the 90% gross income test described above. If the Fund’s income or gain from a particular investment or activity were determined to constitute

non-qualifying

income, which in certain cases may be determined retroactively, and the Fund’s nonqualifying income from all sources were to exceed 10% of its gross income in any taxable year, the Fund would fail to qualify as a RIC unless it were eligible to and did pay a tax at the Fund level.

Investors Should Retain This Supplement for Future Reference

PFN_SUPP1_062426

SEC Form 424B3 filed by PIMCO Income Strategy Fund II