(MSIF Insight Portfolio - Class IS) | (Insight Portfolio)

Investment Objective

The Insight 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 and hold Class IS shares of the Fund. The Fund does not charge any sales loads or other fees when you purchase or redeem Class IS shares.

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

Annual Fund Operating Expenses - (Insight Portfolio)	Class IS ­
Advisory Fee	0.80%
Distribution and/or Shareholder Service (12b-1) Fee	none
Other Expenses	14.32%	[1]
Total Annual Fund Operating Expenses	15.12%	[2]
Fee Waiver and/or Expense Reimbursement	14.12%	[2]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	1.00%	[2]

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). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If You SOLD Your Shares

Expense Example - (Insight Portfolio)	1 Year	3 Years
Class IS | ­ | USD ($)	102	2,937

If You HELD Your Shares

Expense Example, No Redemption - (Insight Portfolio)	1 Year	3 Years
Class IS | ­ | USD ($)	102	2,937

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 Fund performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 101% 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 cyclical companies with market capitalizations within the range of companies included in the Russell 3000® Value Index. As of December 31, 2017, these market capitalizations ranged between $16.4 million and $381 billion.

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 to invest in companies with strong name recognition, sustainable competitive advantages and ample growth prospects at an attractive discount to future cash flow generation capacity or asset value. The Adviser typically favors companies with the ability to generate attractive free cash flow yields. The Adviser generally considers selling a portfolio holding when it determines that the holding no longer satisfies its investment criteria.

The Fund's equity investments may include common and preferred stocks, convertible securities and equity-linked securities, rights and warrants to purchase common stocks, depositary receipts, exchange-traded funds ("ETFs"), limited partnership interests and other specialty securities having equity features. The Fund may invest in privately placed and restricted securities.

The Fund may invest up to 25% of its total assets in foreign securities, which may include emerging market securities.

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. To the extent that the Fund invests in convertible securities, and the convertible security's investment value is greater than its conversion value, its price will be likely to increase when interest rates fall and decrease when interest rates rise. If the conversion value exceeds the investment value, the price of the convertible security will tend to fluctuate directly with the price of the underlying security.

• Small and Medium Capitalization Companies. Investments in small and medium capitalization companies may involve greater risk than investments in larger, more established companies. The securities issued by small and medium capitalization companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.

• 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, 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. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed 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.

• Liquidity. The Fund's investments in restricted and illiquid securities may entail greater risk than investments in other types of securities. These securities may be more difficult to sell, particularly in times of market turmoil. Additionally, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Illiquid securities may be more difficult to value. If the Fund is forced to sell an illiquid 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.

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 I 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, as well as indices that represent groups of similar mutual funds, over time. 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 (800) 548-7786.

Annual Total Returns—Calendar Years

High Quarter	03/31/13	13.32%
Low Quarter	09/30/15	-9.06%

Average Annual Total Returns (for the calendar periods ended December 31, 2017)

Average Annual Total Returns - (Insight Portfolio) - ­		Past One Year	Past Five Years	Since Inception		Inception Date
Class I	[1]	18.28%	16.97%	18.75%		Dec. 28, 2011
Class I | Return After Taxes on Distributions	[1],[2]	17.04%	14.11%	15.89%		Dec. 28, 2011
Class I | Return After Taxes on Distributions and Sale of Fund Shares	[1]	10.71%	12.68%	14.31%		Dec. 28, 2011
Class IS	[1]
Russell 3000® Value Index (reflects no deduction for fees, expenses or taxes)	[3]	13.19%	13.95%	14.66%	[4]
Lipper Multi-Cap Core Funds Index (reflects no deduction for taxes)	[5]	20.54%	14.24%	14.68%	[4]

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 Class IS shares will vary from Class I 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.

[1] Other Expenses have been estimated for the current fiscal year.

[2] The Fund's "Adviser," Morgan Stanley Investment Management Inc., has agreed to reduce its advisory fee and/or reimburse the Fund so that Total Annual Fund Operating Expenses, excluding certain investment related expenses, taxes, interest and other extraordinary expenses (including litigation), will not exceed 1.00% 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.

[1] Class I shares are not offered in the Prospectus. Class IS shares of the Fund had not commenced operations as of December 31, 2017. Class IS shares would have substantially similar annual returns because the shares are invested in the same portfolio of securities and the annual returns would differ only to the extent that the Classes do not have the same expenses. The returns for Class IS shares are expected to be higher than the returns for Class I shares of the Fund as expenses of Class IS shares are estimated to be lower. Return information for the Fund's Class IS shares will be shown in future prospectuses offering the Fund's Class IS shares after the Fund's Class IS shares have a full calendar year of return information to report.

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

[3] The Russell 3000® Value Index measures the performance of those companies in the Russell 3000® Index with lower price-to-book ratios and lower forecasted growth values. The Russell 3000® Index measures the performance of the largest 3000 U.S. companies representing approximately 98% of the investable U.S. equity market. It is not possible to invest directly in an index.

[4] Since Inception reflects the inception date of Class I.

[5] The Lipper Multi-Cap Core Funds Index is an equally-weighted performance index of the largest qualifying funds (based on net assets) in the Lipper Multi-Cap Core Funds classification. There are currently 30 funds represented in this Index.