Morgan Stanley Institutional Fund, Inc.

Developing Opportunity Portfolio

Summary Prospectus | April 30, 2021


Share Class and Ticker Symbols
Class I	Class A	Class C	Class IS
MDOEX	MDOAX	MDOBX	MDODX

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/DevelopingOpportunityPortfolio. 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, 2021 (as may be supplemented from time to time), are incorporated by reference into this Summary Prospectus.

Investment Objective

The Developing 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 shares of the Fund. 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.

For purchases of Class A shares, you may qualify for a sales charge discount if the cumulative net asset value per share (“NAV”) of Class A shares of the Fund being purchased in a single transaction, together with the NAV of any Class A and Class C shares of the Fund already held in Related Accounts (as defined in the section of the Prospectus entitled “Shareholder Information—Sales Charges Applicable to Purchases of Class A Shares”) as of the date of the transaction as well as Class A, Class L and Class C shares of any other Morgan Stanley Multi-Class Fund excluding Morgan Stanley Institutional Fund Trust Short Duration Income, Ultra-Short Income and Ultra-Short Municipal Income Portfolios (as defined in the section of the Prospectus entitled “Shareholder Information—Exchange Privilege”) and including shares of Morgan Stanley Money Market Funds (as defined in the section of the Prospectus entitled “Shareholder Information—Exchange Privilege”) that you acquired in an exchange of Class A or Class C shares of the Fund or Class A, Class L or Class C shares of another Morgan Stanley Multi-Class Fund excluding Morgan Stanley Institutional Fund Trust Short Duration Income, Ultra-Short Income and Ultra-Short Municipal Income Portfolios already held in Related Accounts as of the date of the transaction, amounts to $25,000 or more. More information about this combined purchase discount and other discounts is available from your authorized financial intermediary, on page 43 of the Prospectus in the section entitled “Shareholder Information—Sales Charges Applicable to Purchases of Class A Shares” and in Appendix A attached to the Prospectus.

Class I shares may be available on brokerage platforms of firms that have agreements with the Fund’s principal underwriter permitting such firms to (i) offer Class I shares solely when acting as an agent for the investor and (ii) impose on an investor transacting in Class I shares through such platforms a commission and/or other forms of compensation to the broker. Shares of the Fund are available in other share classes that have different fees and expenses.

Morgan Stanley Institutional Fund, Inc. Prospectus | Fund Summary

Developing Opportunity Portfolio (Con’t)

Shareholder Fees (fees paid directly from your investment)


	Class I	Class A	Class C	Class IS
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	None	5.25%	None	None
Maximum deferred sales charge (load) (as a percentage based on the lesser of the offering price or NAV at redemption)	None	None¹	1.00%²	None
Redemption Fee (as a percentage of the amount redeemed on redemptions made within 30 days of purchase)	2.00%	2.00%	2.00%	2.00%

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


	Class I	Class A	Class C	Class IS
Advisory Fee³	0.90%	0.90%	0.90%	0.90%
Distribution and/or Shareholder Service (12b-1) Fee	None	0.25%	1.00%	None
Other Expenses⁴	0.52%	0.58%	0.64%	16.78%
Total Annual Fund Operating Expenses⁵	1.42%	1.73%	2.54%	17.68%
Fee Waiver and/or Expense Reimbursement⁵	0.27%	0.23%	0.29%	16.58%
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement⁵	1.15%	1.50%	2.25%	1.10%

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 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). After eight years, Class C shares of the Fund generally will convert automatically to Class A shares of the Fund. The example for Class C shares reflects the conversion to Class A shares after eight years. Please refer to the section of the Prospectus entitled “Shareholder Information—Conversion Features” for more information. Although your actual costs may be higher or lower, based on these assumptions your costs would be:


If You SOLD Your Shares
	1 Year	3 Years	5 Years	10 Years
Class I	$ 117	$ 423	$ 751	$ 1,679
Class A	$ 670	$ 1,020	$ 1,394	$ 2,441
Class C	$ 328	$ 763	$ 1,325	$ 2,655
Class IS	$ 112	$ 3,335	$ 5,792	$ 9,676


If You HELD Your Shares
	1 Year	3 Years	5 Years	10 Years
Class I	$ 117	$ 423	$ 751	$ 1,679
Class A	$ 670	$ 1,020	$ 1,394	$ 2,441
Class C	$ 228	$ 763	$ 1,325	$ 2,655
Class IS	$ 112	$ 3,335	$ 5,792	$ 9,676

Investments in Class A shares that are not subject to any sales charges at the time of purchase are subject to a contingent deferred sales charge (“CDSC”) of 1.00% that will be imposed if you sell your shares within 18 months after the last day of the month of purchase, except for certain specific circumstances. See “Shareholder Information—How To Redeem Fund Shares” for further information about the CDSC waiver categories.

2	The Class C CDSC is only applicable if you sell your shares within one year after purchase. See “Shareholder Information—How To Redeem Fund Shares” for a complete discussion of the CDSC.

“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,” 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.

4	“Other Expenses” include expenses of the Fund’s most recent fiscal year and estimated expenses of the Subsidiary. Other Expenses have been restated to reflect current estimated fees.

The Fund’s Adviser has agreed to reduce 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 1.15% for Class I, 1.50% for Class A, 2.25% for Class C and 1.10% for Class IS. The fee waivers and/or expense reimbursements will continue for at least one year 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. Total Annual Fund Operating Expenses and Fee Waiver and/or Expense Reimbursement have been restated to reflect current estimated fees.

Morgan Stanley Institutional Fund, Inc. Prospectus | Fund Summary

Developing Opportunity Portfolio (Con’t)

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 period February 14, 2020 (commencement of operations) through December 31, 2020, the Fund’s portfolio turnover rate was 18% 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 equity securities of issuers located or operating in developing or emerging market countries, with capitalizations within the range of companies included in the MSCI Emerging Markets Net Index. For purposes of this prospectus, “developing markets,” “developing market countries,” “emerging markets” and “emerging market countries” and similar terms are used interchangeably but refer to the same underlying markets and countries.

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 companies within developing markets 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 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.

Under normal market conditions, at least 80% of the Fund’s assets will be invested in equity securities of issuers located or operating in developing markets. This policy may be changed without shareholder approval; however, you would be notified upon 60 days’ notice in writing of any changes.

For purposes of the Fund’s 80% policy, developing market countries will include frontier emerging market countries. The term “frontier emerging markets” refers to those emerging market countries outside the “mainstream” emerging markets, whose capital markets have traditionally been difficult for foreign investors to enter or are in early stages of capital market and/or economic development. The countries that comprise frontier emerging markets may change from time to time.

For purposes of maintaining exposure of at least 80% of the Fund’s assets to equity securities of issuers located or operating in developing markets, 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 in developing markets. 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”).

Principal Risks

There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this 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. The prices of equity securities fluctuate, and sometimes widely fluctuate, 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 and political conditions.

•

Foreign and Emerging Market Securities. Investments in foreign markets entail special risks such as currency, political, economic and market risks. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs, 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 ongoing 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

Morgan Stanley Institutional Fund, Inc. Prospectus | Fund Summary

Developing Opportunity Portfolio (Con’t)

capital and are more vulnerable to diplomatic developments, the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental 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 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 in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market 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. 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 markets 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. To the extent hedged 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 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. Economic sanctions may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar governmental actions could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities or groups of securities, and thus may make the Fund’s investments in such securities less liquid or more difficult to value. In addition, as a result of economic sanctions, the Fund may be forced to sell or otherwise dispose of investments at inopportune times or prices.

•

Frontier Emerging Market Securities. Investing in the securities of issuers operating in frontier emerging markets involves a high degree of risk and special considerations not typically associated with investing in the securities of other foreign or U.S. issuers. In addition, the risks associated with investing in the securities of issuers operating in emerging market countries are magnified when investing in frontier emerging market countries. These types of investments could be affected by factors not usually associated with investments in U.S. issuers, including risks associated with expropriation and/or nationalization, political or social instability, pervasiveness of corruption and crime, armed conflict, the impact on the economy of civil war, religious or ethnic unrest and the withdrawal or non-renewal of any license enabling the Fund to trade in securities of a particular country, confiscatory taxation, restrictions on transfers of assets, lack of uniform accounting, auditing and financial reporting standards, less publicly available financial and other information, less stringent investor protections and disclosure standards, diplomatic development which could affect U.S. investments in those countries and potential difficulties in enforcing contractual obligations. These risks and special considerations make investments in companies operating in frontier emerging market countries highly speculative in nature and, accordingly, an investment in the Fund must be viewed as highly speculative in nature and may not be suitable for an investor who is not able to afford the loss of his or her entire investment. To the extent that the Fund invests a significant percentage of its assets in a single frontier emerging market country, the Fund will be subject to heightened risk associated with investing in frontier emerging market countries and additional risks associated with that particular country. A government of a frontier emerging market country may limit or cause delay in the convertibility or repatriation of its currency and therefore could adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. From time to time, certain of the companies in which the Fund expects to invest may operate in, or have dealings with, countries subject to sanctions or embargoes imposed by the U.S. Government and the United Nations and/or countries identified by the U.S. Government as state sponsors of terrorism. A company may suffer damage to its reputation if it is identified as such a company and, as an investor in such companies, the Fund will be indirectly subject to those risks. Certain frontier 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. 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 frontier markets countries. In addition, a substantial portion of 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. To the extent hedged 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

Morgan Stanley Institutional Fund, Inc. Prospectus | Fund Summary

Developing Opportunity Portfolio (Con’t)

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 could reduce or preclude the opportunity for gain if the value of the currency moves 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 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. Economic sanctions may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar governmental actions could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities or groups of securities, and thus may make the Fund’s investments in such securities less liquid or more difficult to value. In addition, as a result of economic sanctions, the Fund may be forced to sell or otherwise dispose of investments at inopportune times or prices.

•

China Risk. Investments in securities of Chinese issuers, including A-shares, involve risks associated with investments in foreign markets as well as special considerations not typically associated with investments in the U.S. securities markets. For example, the Chinese government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation and/or state ownership and actions of the Chinese central and local government authorities continue to have a substantial effect on economic conditions in China. In addition, the Chinese government has taken 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. Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions 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 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 the Fund may be forced to sell such restricted securities and incur a loss as a result.

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.

•

Liquidity. The Fund may make investments that are illiquid or restricted or that may become 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.

•

Focused Investing. To the extent that the Fund invests in a limited number of issuers, the Fund will be more susceptible to negative events affecting those issuers and a decline in the value of a particular instrument may cause the Fund’s overall value to decline to a greater degree than if the Fund were invested more widely.

•

Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which may change due to economic and other events that affect markets generally, as well as those that affect particular regions, countries, industries, companies or governments. These events may be sudden and unexpected, and could adversely affect the liquidity of the Fund’s investments, which may in turn impact valuation, 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, epidemics and pandemics, terrorism, conflicts and social unrest) adversely interrupt the global economy and financial markets. It is difficult to predict when events affecting the U.S. or global financial markets may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance 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.

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.

Morgan Stanley Institutional Fund, Inc. Prospectus | Fund Summary

Developing Opportunity Portfolio (Con’t)

Performance Information

As of the date hereof, the Fund has not yet completed a full calendar year of investment operations. Upon the completion of a full calendar year of investment operations by the Fund, this section will include charts that provide some indication of the risks of an investment in the Fund, by showing the difference in annual total returns, highest and lowest quarterly returns and average annual total returns (before and after taxes) compared to a benchmark index selected for the Fund. Performance information for the Fund will be available online at www.morganstanley.com/im or by calling toll-free 1-800-548-7786.

Fund Management

Adviser. Morgan Stanley Investment Management Inc.

Sub-Adviser. Morgan Stanley Investment Management Company.

Portfolio Manager. 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 or Sub-Adviser	Date Began Managing Fund
Kristian Heugh	Managing Director of the Sub-Adviser	Since Inception

Purchase and Sale of Fund Shares

The minimum initial investment generally is $5 million for Class I shares and $1,000 for each of Class A and Class C shares of the Fund. To purchase Class IS shares, an investor must meet a minimum initial investment of $10 million or be a defined contribution, defined benefit or other employer sponsored employee benefit plan, in each case provided that the plan trades on an omnibus level, whether or not 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 DST Asset Manager Solutions, Inc., P.O. Box 219804, Kansas City, MO 64121-9804), by telephone (1-800-548-7786) 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”). In addition, you can sell Fund shares at any time by enrolling in a systematic withdrawal plan. If you sell Class A shares or Class C shares, your net sale proceeds are reduced by the amount of any applicable CDSC. 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 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 Fund 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.

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