# EDGAR Filing Document

**Accession Number:** 0000836487
**File Stem:** 0001133228-26-007589
**Filing Date:** 2026-4
**Character Count:** 39636
**Document Hash:** b7cbca79d3950141cde119b99a132de2
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001133228-26-007589.hdr.sgml**: 20260430

**ACCESSION NUMBER**: 0001133228-26-007589

**CONFORMED SUBMISSION TYPE**: 497K

**PUBLIC DOCUMENT COUNT**: 4

**FILED AS OF DATE**: 20260430

**DATE AS OF CHANGE**: 20260430

**EFFECTIVENESS DATE**: 20260430

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MORGAN STANLEY INSTITUTIONAL FUND INC
- **CENTRAL INDEX KEY:** 0000836487

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** MD
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 497K
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 033-23166
- **FILM NUMBER:** 26927040

**BUSINESS ADDRESS:**
- **STREET 1:** 1585 BROADWAY
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10036
- **BUSINESS PHONE:** 800-548-7786

**MAIL ADDRESS:**
- **STREET 1:** 1585 BROADWAY
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10036

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MORGAN STANLEY DEAN WITTER INSTITUTIONAL FUND INC
- **DATE OF NAME CHANGE:** 19990329

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MORGAN STANLEY INSTITUTIONAL FUND INC
- **DATE OF NAME CHANGE:** 19920703

## Series and Classes Contracts Data

### International Opportunity Portfolio (Series ID: S000027992)

| Class ID   | Class Name   | Ticker Symbol   |
|:---|:---|:---|
| C000198820 | Class IR     | MRNPX           |

![](sp17278img002.jpg) <br>

**Morgan Stanley Institutional** **Fund, Inc.**

International Opportunity Portfolio

**Summary Prospectus** **\|** April 30, 2026<br>

---

| |
|:---|
| **Share Class and Ticker Symbol** |
| **Class IR** |
| MRNPX |

---

Before you invest, you may want to review the Fund's statutory prospectus ("Prospectus"), which contains more information about the Fund and its risks. You can find the Fund's Prospectus and other information about the Fund, including the Statement of Additional Information ("SAI") and the most recent Annual and Semi-Annual Reports to Shareholders ("Shareholder Reports"), online at www.morganstanley.com/im/MSIFInternationalOpportunityIR. You can also get this information at no cost by calling toll-free 1-866-414-6349 or by sending an e-mail request to orders@mysummaryprospectus.com. The Fund's Prospectus and SAI, both dated April 30, 2026 (as may be supplemented from time to time), are incorporated by reference into this Summary Prospectus.

**Investment Objective**

The International Opportunity Portfolio (the "Fund") seeks long-term capital appreciation.

**Fees and Expenses**

The table below describes the fees and expenses that you may pay if you buy, hold and sell Class IR shares of the Fund. The Fund does not charge any sales loads or other fees when you purchase Class IR shares. **You may pay fees other than the fees** **and expenses of the Fund, such as brokerage commissions and other fees charged by financial intermediaries, which are** **not reflected in the tables and examples below.**

**Shareholder Fees** (fees paid directly from your investment)

---

| | |
|:---|:---|
|  | **Class IR** |
| Maximum sales charge (load) imposed on purchases (as a percentage of offering price) |  |
| Maximum deferred sales charge (load) (as a percentage based on the lesser of the offering price or net asset value per share ("NAV") at redemption) |  |
| Redemption Fee (as a percentage of the amount redeemed on redemptions made within 30 days of purchase) | 2.00% |

---

**Annual Fund Operating Expenses** (expenses that you pay each year as a percentage of the value of your investment)

---

| | |
|:---|:---|
|  | **Class IR** |
| Advisory Fee<sup>1</sup> | 0.80% |
| Distribution and/or Shareholder Service (12b-1) Fee |  |
| Other Expenses<sup>2</sup> | 15.10% |
| Total Annual Fund Operating Expenses<sup>3</sup> | 15.90% |

---

![](sp17278img003.jpg) <br>

SU-MSIFIR-13

------

Morgan Stanley Institutional Fund, Inc. Prospectus \| **Fund Summary**

International Opportunity Portfolio (Con't)

---

| | |
|:---|:---|
|  | **Class IR** |
| Fee Waiver and/or Expense Reimbursement<sup>3</sup> | 14.96% |
| Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement<sup>3</sup> | 0.94% |

---

---

| | |
|:---|:---|
| 1 | "Advisory Fee" includes the management fee of a wholly-owned subsidiary of the Fund organized as a company under the laws of the Cayman Islands (the "Subsidiary"). The Fund's "Adviser" and "Administrator," Morgan Stanley Investment Management Inc., has agreed to waive or credit a portion of the advisory fee in an amount equal to the management fee paid to the Adviser by the Subsidiary. |

---

2 "Other Expenses" include expenses of the Fund's and Subsidiary's most recent fiscal year.

---

| | |
|:---|:---|
| 3 | The Adviser has agreed to waive all or a portion of its advisory fee and/or reimburse the Fund so that Total Annual Fund Operating Expenses, excluding acquired fund fees and expenses (as applicable), certain investment related expenses, taxes, interest and other extraordinary expenses (including litigation), will not exceed 0.94% for Class IR. The fee waivers and/or expense reimbursements will continue for at least one year from the date of this Prospectus or until such time as the Board of Directors of Morgan Stanley Institutional Fund, Inc. (the "Company") acts to discontinue all or a portion of such waivers and/or reimbursements when it deems such action is appropriate. |

---

**Example**

The example below is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The example assumes that you invest $10,000 in the Fund, your investment has a 5% return each year and that the Fund's operating expenses remain the same (except that the example incorporates the fee waiver and/or expense reimbursement arrangement for only the first year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

---

| | | | | |
|:---|:---|:---|:---|:---|
| **If You SOLD Your Shares** | **If You SOLD Your Shares** | **If You SOLD Your Shares** | **If You SOLD Your Shares** | **If You SOLD Your Shares** |
|  | **1 Year** | **3 Years** | **5 Years** | **10 Years** |
| Class IR | $96 | $3054 | $5403 | $9369 |

---

---

| | | | | |
|:---|:---|:---|:---|:---|
| **If You HELD Your Shares** | **If You HELD Your Shares** | **If You HELD Your Shares** | **If You HELD Your Shares** | **If You HELD Your Shares** |
|  | **1 Year** | **3 Years** | **5 Years** | **10 Years** |
| Class IR | $96 | $3054 | $5403 | $9369 |

---

**Portfolio Turnover**

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 25% of the average value of its portfolio.

**Principal Investment Strategies**

Under normal market conditions, the Adviser seeks to achieve the Fund's investment objective by investing primarily in established and emerging companies on an international basis, with capitalizations within the range of companies included in the MSCI All Country World ex USA Index.

The Adviser emphasizes a bottom-up stock selection process, seeking attractive investments on an individual company basis. In selecting securities for investment, the Adviser seeks high quality established and emerging companies that the Adviser believes are undervalued at the time of purchase. Fundamental research drives the investment process. The Adviser typically favors companies it believes have sustainable competitive advantages that can be monetized through growth. The investment process integrates analysis of sustainability with respect to disruptive change, financial strength, environmental and social externalities and governance (also referred to as ESG). The Adviser typically focuses a significant portion of the Fund's investments in a limited number of issuers, which may be in the same industry, sector or geographic region. The Adviser generally considers selling a portfolio holding when it determines that the holding no longer satisfies its investment criteria.

The Adviser views incorporating ESG-related potential risks and opportunities within the investment process as important to ensure long-term stewardship of capital. Over extended time horizons, the Adviser believes that ESG risks are more likely to materialize and externalities not borne by the company are more likely to be priced into the value of securities. Since ESG risks could potentially impact the risk and reward profile of investment opportunities, the Adviser typically engages company management in constructive discussions on a range of ESG issues the Adviser deems materially important.

**2**

------

Morgan Stanley Institutional Fund, Inc. Prospectus \| **Fund Summary**

International Opportunity Portfolio (Con't)

The Fund may invest in China A-Shares (shares of publicly traded companies based in mainland China) listed and traded on the Shanghai Stock Exchange through the Shanghai-Hong Kong Stock Connect program, as well as China A-Shares listed and traded on the Shenzhen-Hong Kong Stock Connect program (collectively, "Stock Connect").

The Fund may also invest in American Depositary Receipts ("ADRs"), Global Depositary Receipts ("GDRs") and other types of depositary receipts with respect to issuers located or operating outside of the United States. The Fund may invest in equity securities. The Fund may also invest in privately placed and restricted securities.

The Fund invests primarily in securities of companies located in Europe, Japan, Asia, the Pacific Basin, Latin America, the Middle East and Africa. The Fund may also invest in securities of companies located in the United States to a limited extent.

**Principal Risks**

There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund. Investments in the Fund involve risks and you should not rely on the Fund as a complete investment program. The relative significance of each risk factor summarized below may change over time and you should review each risk factor carefully because any one or more of these risks may result in losses to the Fund. The principal risks of investing in the Fund include:

• **Equity Securities.** In
 general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign
 stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the
 past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or
 widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition
 of the issuer, including general market, economic, political and public health conditions.  During periods when equity
 securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress,
 the Fund's investments in equity securities are subject to heightened risks.

The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund's equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund's equity securities will return to previous levels.

• **Active Management Risk.** In pursuing the Fund's investment objective, the Adviser has considerable leeway in deciding which
 investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in
 its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such
 decisions will affect the Fund's performance.

• **Focused Investing.** Although
 the Fund is a diversified investment company under the Investment Company Act of 1940 (the "1940
 Act"), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same
 industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative
 events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument
 may cause the Fund's overall value to be more volatile and decline to a greater degree than if the Fund were invested
 more widely.

• **Foreign and Emerging Market Securities.** Investments in foreign markets entail special risks, such as currency, political (including
 geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may
 be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards,
 higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation
 associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically
 been considered stable may become more volatile and subject to increased risk due to developments and changing
 conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has
 increased the probability that adverse developments and conditions in one country or region will affect the stability of economies
 and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries
 or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military, or other
 conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities
 and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or
 retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other
 actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or
 the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign
 investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or

**3**

------

Morgan Stanley Institutional Fund, Inc. Prospectus \| **Fund Summary**

International Opportunity Portfolio (Con't)

cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty's legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund's investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund's ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund's investments, significantly delay or prevent the settlement of the Fund's securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund's ability to meet its investment objective or invest in accordance with its investment strategies.

• **Market and Geopolitical Risk.** The value of your investment in the Fund is based on the values of the Fund's investments, which
 change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those
 that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset
 classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or
 income generated by) and liquidity of the Fund's investments, which may in turn impact the Fund's ability to sell securities
 and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social,
 political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics,
 terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat
 and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or
 otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global
 financial markets or economies may occur, the effects that such events may have and the duration of those effects (which
 may last for extended periods). These types of events may negatively impact broad segments of businesses and populations
 and have a significant and rapid negative impact on the performance or value of the Fund's investments, adversely
 affect and increase the volatility of the Fund's share price and exacerbate pre-existing risks to the Fund. The frequency
 and magnitude of resulting changes in the value of the Fund's investments cannot be predicted.

• **Liquidity.** The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in
 response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments
 in other types of securities. These investments may be more difficult to value or sell, particularly in times of market
 turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced
 to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security
 at a loss or for less than its fair value and may be unable to sell the security at all.

• **Information Technology Sector Risk.** To the extent the Fund invests a substantial portion of its assets in the information technology
 sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology
 sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition,
 and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.

• **Consumer Discretionary Sector Risk.** To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary
 sector, the Fund will be particularly susceptible to the risks associated with companies operating in such sector.
 Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall
 domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange
 rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected
 by factors such as reduced disposable household income, reduced consumer spending, and changing demographics
 and consumer tastes.

**4**

------

Morgan Stanley Institutional Fund, Inc. Prospectus \| **Fund Summary**

International Opportunity Portfolio (Con't)

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

• **Financials Sector Risk.** To
 the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have
 an adverse impact on this sector may have a disproportionate impact on the Fund's performance. The financials sector can
 be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and
 asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation,
 and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on
 the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation
 or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations
 and profitability of the financials sector.

• **China Risk.** Investments
 in securities of Chinese issuers involve risks associated with investments in foreign markets as well as
 special considerations not typically associated with investments in the  U.S. markets or other foreign (including emerging) markets.
 For example, the Chinese government has historically exercised substantial control over virtually every sector of the
 Chinese economy through administrative regulation, state ownership and/or other involvement. Actions of the Chinese central
 and local government authorities continue to have a substantial effect on economic conditions in China and operations
 of particular Chinese companies. In addition, the Chinese government has actively intervened in Chinese companies'
 operations and structures and taken (and may continue to take) actions that influenced the prices at which certain
 goods may be sold, encouraged companies to invest or concentrate in particular industries, induced mergers between
 companies in certain industries and induced private companies to publicly offer their securities. Investments in China
 involve risk of a total loss due to government action or inaction or other adverse circumstances.

Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions, trading policies and taxation of imports of its primary trading partners, such as the United States, Japan and South Korea, would adversely impact the Chinese economy and the Fund's investments. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth or the value of investments in China. An economic downturn in China would adversely impact the Fund's investments. In addition, certain securities are, or may in the future, become restricted and/or sanctioned by the U.S. government or other governments and the Fund may be forced to sell or unable to sell such securities and incur a loss as a result and the Fund may be unable to purchase securities of Chinese issuers from time to time.

U.S. relations with China are strained, because of, among other things, a series of trade, international treaty, tax, and sanctions actions taken by the United States and China against each other, including the designation of China as a "foreign adversary" of the U.S., as well as countersanctions or countermeasures from the Chinese government that have been triggered or are expected to be triggered. Moreover, recent developments in relations between the U.S., other trading partners and China have heightened concerns (and the realization) of increased tariffs and restrictions on trade between the two countries, such as the potential for an escalation in trade tensions or a trade war. Increases in tariffs or trade restrictions (and threats thereof) could lead to a significant reduction in international trade, which could have a negative impact on China's export industry, Chinese issuers, the liquidity or price of the Fund's direct or indirect investments in China and, therefore, the Fund's investments.

These and other developments, including government actions or inactions, would likely result in significant illiquidity risk or losses or forced disposition for Chinese investments. The Chinese securities markets are emerging markets characterized by a relatively small number of equity issues and relatively low trading volume, resulting in decreased liquidity, greater price volatility (caused by, among other things, military, diplomatic, or trade conflicts and government intervention in economic and securities markets), and potentially fewer investment opportunities for the Fund. The Fund's investments in Chinese securities are also subject to additional risks associated with differing regulatory and audit requirements in the Chinese securities market as compared to the U.S. securities market, including a lack of reliable audits and other financial information regarding many Chinese companies and heightened risk of market manipulation and fraud, which may be increased through actions taken by the Chinese government. In addition, the relationship between China and Taiwan is particularly sensitive, and hostilities between China and Taiwan, including continued threats by China to invade and control Taiwan, present a significant risk to the Fund's investments in China. Ongoing political tension between the People's Republic of China and the Hong Kong Special Administrative Region may have impacts on the economy of Hong Kong, and these impacts remain uncertain.

*Risks of Investing through Stock Connect.* The Fund may invest in A-shares listed and traded through Stock Connect, or on such other stock exchanges in China which participate in Stock Connect from time to time or in the future. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund's investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program's continued existence or whether future developments regarding the program may restrict or adversely affect the Fund's investments or returns. Because certain

**5**

------

Morgan Stanley Institutional Fund, Inc. Prospectus \| **Fund Summary**

International Opportunity Portfolio (Con't)

transactions through Stock Connect may not be subject to certain investor protection programs, the Fund may be exposed to the risks of default of the broker(s) they engage in their trading in China A Shares.

• **Variable Interest Entities.** Chinese operating companies sometimes rely on variable interest entity ("VIE") structures to raise
 capital from non-Chinese investors because of Chinese government limitations or prohibitions on direct foreign ownership
 in certain industries. In a VIE structure, a series of contractual arrangements are entered into between a holding company
 domiciled outside of China and a Chinese operating company or companies, which are intended to mimic direct ownership
 in the operating company, but in many cases these arrangements have not been tested in court and it is not clear that
 the contracts are enforceable or that the structures will otherwise work as intended. The offshore holding company, which
 is not a Chinese operating company, then issues exchange-traded shares that are sold to the public, including non- Chinese
 investors (such as the Fund). In addition to the risks generally associated with investing in China and a Chinese operating
 company, the shares of the holding company purchased by the Fund would not be equity ownership interests in the
 Chinese operating company and the Fund's interest would be subject to substantial legal, operational and other risks associated
 with the company's use of the VIE structure. For example, the Chinese government has not approved VIE structures
 and at any time without advance notice the Chinese government or a Chinese regulator or court could determine that
 the contractual arrangements constituting part of the VIE structure are unenforceable or do not comply with applicable law
 or regulations, these laws or regulations could change or be interpreted differently in the future, and the Chinese government
 also may with no advance notice otherwise intervene in or exert influence over VIE structures or the related Chinese
 operating companies. If any of these or similar risks or developments materialize, the Fund's investment in the holding
 company may suddenly and significantly decline in value or become worthless because of, among other things, difficulty
 enforcing (or the inability to enforce) the contractual arrangements or materially adverse effects on the Chinese operating
 company's performance. In these circumstances, the Fund could experience significant or total losses with no recourse
 available. From time to time, the Fund's investments in  U.S.-listed shell companies relying on VIE structures to obtain
 exposure to Chinese operating companies could be significant. A decline or worsening in diplomatic or other relations between
 the U.S. and China could increase the risks associated with the VIE structure.

• **Foreign Currency Forward Exchange Contracts.** To the extent the Fund seeks to hedge its foreign currency exposure by the
 use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract
 amounts and the value of the securities involved will not generally be possible because the future value of such securities
 in foreign currencies will change as a consequence of market movements in the value of those securities between the
 date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce
 or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken
 and that foreign currency forward exchange contracts create exposure to currencies in which the Fund's securities are
 not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and
 the risk of loss from the insolvency or bankruptcy of the  counterparty to the contract or the failure of the counterparty to
 make payments or otherwise comply with the terms of the contract.

Please see "Additional Information About Fund Investment Strategies and Related Risks" in the Fund's prospectus for a more detailed description of risks of investing in the Fund. Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.

**Performance Information**

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's Class IR shares' performance from year-to-year and by showing how the Fund's average annual returns for the past one and five year periods and since inception compare with those of a broad measure of market performance. The Fund's past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available online at www.morganstanley.com/im or by calling toll-free 1-800-869-6397.

**6**

------

Morgan Stanley Institutional Fund, Inc. Prospectus \| **Fund Summary**

International Opportunity Portfolio (Con't)

**Annual Total Returns—Calendar Years**

![](sp17278img001.jpg)

During the periods shown in the bar chart above:

---

| | | |
|:---|:---|:---|
| **High Quarter** | 06/30/20 | 34.04% |
| **Low Quarter** | 03/31/22 | -26.32% |

---

**Average Annual Total Returns**

(for the calendar periods ended December 31, 2025)

---

| | | | |
|:---|:---|:---|:---|
|  | **Past**<br>**One Year** | **Past**<br>**Five Years** | **Since**<br>**Inception** |
| **Class IR** (commenced operations on 6/15/2018) | **Class IR** (commenced operations on 6/15/2018) |  |  |
| Return Before Taxes | 12.74% | -2.74% | 4.88% |
| Return After Taxes on Distributions<sup>1</sup> | 12.86% | -3.15% | 4.57% |
| Return After Taxes on Distributions and Sale of Fund Shares | 7.66% | -2.08% | 3.83% |
| MSCI All Country World ex USA Net Index (reflects no deduction for fees, expenses or taxes)<sup>2</sup> | 32.39% | 7.91% | 7.40%<sup>3</sup> |

---

1 These returns do not reflect any tax consequences from a sale of your shares at the end of each period.

---

| | |
|:---|:---|
| 2 | The MSCI All Country World ex USA Net Index is a free float-adjusted market capitalization weighted index designed to measure the equity market performance of developed and emerging markets, excluding the United States. The term "free float" represents the portion of shares outstanding that are deemed to be available for purchase in the public equity markets by investors. The performance of the index is listed in U.S. dollars and assumes reinvestment of net dividends. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties. It is not possible to invest directly in an index. |

---

3 Since Inception reflects the inception date of Class IR.

The after-tax returns shown in the table above are calculated using the historical highest individual federal marginal income tax rates during the period shown and do not reflect the impact of state and local taxes. After-tax returns for the Fund's other classes will vary from Class IR shares' returns. Actual after-tax returns depend on the investor's tax situation and may differ from those shown, and after-tax returns are not relevant to investors who hold their Fund shares through tax deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns may be higher than before-tax returns due to an assumed benefit from capital losses that would have been realized had Fund shares been sold at the end of the relevant periods, as applicable.

**7**

------

Morgan Stanley Institutional Fund, Inc. Prospectus \| **Fund Summary**

International Opportunity Portfolio (Con't)

**Fund Management**

**Adviser.** Morgan Stanley Investment Management Inc.

**Portfolio Managers**. The Fund is managed by members of the Global Opportunity team. Information about the member primarily responsible for the day-to-day management of the Fund is shown below:

---

| | | |
|:---|:---|:---|
| **Name** | **Title with Adviser** | **Date Began**<br>**Managing Fund** |
| Kristian Heugh | Managing Director of the Adviser | Since inception |

---

**Purchase and Sale of Fund Shares**

To purchase Class IR shares, an investor must meet a minimum initial investment of $5 million or be a defined contribution, defined benefit or other employer sponsored employee benefit plan, in each case provided that the plan trades through an intermediary that combines its clients' assets in a single omnibus account, whether or not such plan is qualified under the Internal Revenue Code of 1986, as amended (the "Code"), and in each case subject to the discretion of the Adviser. The minimum initial investment may be waived for certain investments. For more information, please refer to the section of the Prospectus entitled "Shareholder Information—Minimum Investment Amounts."

Shares of the Fund may be purchased or sold on any day the New York Stock Exchange ("NYSE") is open for business directly from the Fund by mail (c/o SS&C Global Investor and Distribution Solutions, Inc., P.O. Box 219804, Kansas City, MO 64121-9804), by telephone (1-800-869-6397) or by contacting an authorized third-party, such as a broker-dealer or other financial intermediary that has entered into a selling agreement with the Fund's "Distributor," Morgan Stanley Distribution, Inc. (each, a "Financial Intermediary"). For more information, please refer to the sections of the Prospectus entitled "Shareholder Information—How To Purchase Fund Shares" and "—How To Redeem Fund Shares."

**Tax Information**

The Fund intends to make distributions that may be taxed as ordinary income or capital gains, unless you are investing through a tax-deferred arrangement, such as a 401(k) plan or an individual retirement account.

**Payments to Broker-Dealers and Other Financial Intermediaries**

If you purchase Class IR shares of the Fund through a Financial Intermediary (such as a bank), the Adviser and/or the Distributor may pay the Financial Intermediary for the sale of Class IR shares and related services. These payments, which may be significant in amount, may create a conflict of interest by influencing the Financial Intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your Financial Intermediary's web site for more information. For additional information about the Fund's revenue sharing arrangements for Class IR shares, see the section of the Statement of Additional Information entitled "Revenue Sharing."

------©2026 Morgan Stanley SU-MSIFIR-13