Morgan Stanley Variable Investment Series

The Income Plus Portfolio

Class X

Summary Prospectus | April 28, 2023

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 https://www.morganstanley.com/im/MSVISIncomePlus. 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 28, 2023 (as may be supplemented from time to time), are incorporated by reference into this Summary Prospectus.

Investment Objectives

The Fund seeks as a primary objective to provide a high level of current income by investing primarily in U.S. government securities and other fixed-income securities. As a secondary objective, the Fund seeks capital appreciation but only when consistent with its primary objective.

Fees and Expenses of the Fund

The table below describes the fees and expenses that you may pay if you buy, hold and sell Class X shares of the Fund. The Fund does not charge any sales loads or other fees when you purchase or redeem shares. Total Annual Fund Operating Expenses in the table and the Example below do not reflect the impact of any charges by your insurance company. If they did, expenses would be higher. 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.

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


Advisory Fee	0.42%
Distribution (12b-1) Fee	None
Other Expenses	0.60%
Total Annual Fund Operating Expenses*	1.02%
Fee Waiver and/or Expense Reimbursement*	0.27%
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement*	0.75%

Morgan Stanley Variable Investment Series | Fund Summary

Income Plus Portfolio (Con’t)

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:


	1 Year	3 Years	5 Years	10 Years
Class X	$ 77	$ 298	$ 537	$ 1,223

The Fund’s “Adviser” and “Administrator,” Morgan Stanley Investment Management Inc., has agreed to reduce its advisory fee, its administration 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 0.75% for Class X. 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 Trust’s Board of Trustees acts to discontinue all or a portion of such waivers and/or reimbursements when it deems such action is appropriate.

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. 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 87% of the average value of its portfolio.

Principal Investment Strategies

The Fund will normally invest at least 80% of its assets in (i) U.S. government securities issued or guaranteed as to principal and interest by the U.S. Government, its agencies and instrumentalities, (ii) debt securities rated at the time of purchase within the four highest bond rating categories (“investment grade”) by Moody’s Investors Service, Inc. (“Moody’s”), S&P Global Ratings Group, a division of S&P Global Inc. (“S&P”) or Fitch Ratings Inc. (“Fitch”), or the equivalent by another nationally recognized statistical rating organization (“NRSRO”), or, if not rated, determined to be of comparable quality by the Adviser and (iii) Yankee government bonds (U.S. dollar obligations issued in the United States by foreign governments) rated at the time of purchase as investment grade by Moody’s, S&P or Fitch or the equivalent by another NRSRO, or, if not rated, determined to be of comparable quality by the Adviser. While the Fund retains the flexibility to invest in the foregoing securities, it currently expects that its investment portfolio will consist primarily of investment grade corporate bonds.

The Fund may also invest up to 20% of its net assets in debt securities rated below investment grade by Moody’s, S&P or Fitch or the equivalent by another NRSRO, or, if not rated, determined to be of comparable quality by the Adviser. Securities rated below investment grade are commonly known as “junk bonds.” The Fund may also invest in convertible securities.

The Fund may also invest in securities of foreign issuers, including issuers located in emerging market or developing countries. Securities of such foreign issuers may be denominated in U.S. dollars or in currencies other than U.S. dollars. The Fund will limit its investments in non-U.S. dollar-denominated securities to 30% of the Fund’s assets.

The Fund is not limited as to the maturities of the U.S. Government and other debt securities in which it may invest.

In making investment decisions for the Fund, the Adviser considers both domestic and international economic developments, interest rate trends and other factors. The Adviser evaluates technical considerations such as the relative supply of and demand for corporate notes and U.S. Treasury and agencies’ issues before it decides upon an asset allocation. Similarly, the assessment of the strength of individual companies that issue corporate debt and the overall country risk of sovereign debt obligations contribute to the decision-making process.

The Fund’s investment process incorporates information about environmental, social and governance issues (also referred to as ESG) via an integrated approach within the investment team’s fundamental investment analysis framework. The Adviser may engage with management of certain issuers regarding corporate governance practices as well as what the Adviser deems to be materially important environmental and/or social issues facing a company.

The Fund may invest up to 20% of its net assets in loan-related investments, such as public bank loans made by banks or other financial institutions and loan participations and assignments, which may be rated investment grade or below investment grade.

The Fund may, but it is not required to, use derivatives and similar instruments for a variety of purposes, including hedging, risk management, portfolio management or to earn income. The Fund’s use of derivatives may involve the purchase and sale of derivative instruments such as futures, options, swaps and other similar instruments and techniques. The Fund may utilize foreign currency forward exchange contracts, which are also derivatives, in connection with its investments in foreign securities. These derivative

Morgan Stanley Variable Investment Series | Fund Summary

Income Plus Portfolio (Con’t)

instruments will be counted toward the Fund’s 80% policy discussed above to the extent they have economic characteristics similar to the securities included within that policy.

Principal Risks

There is no assurance that the Fund will achieve its investment objectives, and you can lose money investing in this Fund. The principal risks of investing in the Fund include:

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Asset-Backed Securities. Asset-backed securities are subject to credit (such as a borrower’s default on its mortgage obligation and the default or failure of a guarantee underlying the asset-backed security), interest rate and certain additional risks, including the risk that various federal and state consumer laws and other legal and economic factors may result in the collateral backing the securities being insufficient to support payment on the securities. Some asset-backed securities also entail prepayment risk and extension risk, which may vary depending on the type of asset. Due to these risks, asset-backed securities may become more volatile in certain interest rate environments.

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Fixed-Income Securities. Fixed-income securities are subject to the risk of the issuer’s inability to meet principal and interest payments on its obligations (i.e., credit risk) and are subject to price volatility resulting from, among other things, interest rate sensitivity (i.e., interest rate risk), market perception of the creditworthiness of the issuer and general market liquidity (i.e., market risk). For example, a type of fixed-income securities in which the Fund may invest are corporate debt obligations. In addition to interest rate, credit and other risks, corporate debt obligations are also subject to factors directly related to the issuer, such as the credit rating of the corporation, the corporation’s performance and perceptions of the corporation in the marketplace, and by factors not directly related to the issuer, such as general market liquidity, economic conditions and inflation. The Fund may face a heightened level of interest rate risk in times of monetary policy change and/or uncertainty, such as when the Federal Reserve Board adjusts a quantitative easing program and/or changes rates. A changing interest rate environment increases certain risks, including the potential for periods of volatility, increased redemptions, shortened durations (i.e., prepayment risk) and extended durations (i.e., extension risk). The Fund is not limited as to the maturities (when a debt security provides its final payment) or durations (measure of interest rate sensitivity) of the securities in which it may invest. Securities with longer durations are likely to be more sensitive to changes in interest rates, generally making them more volatile than securities with shorter durations. Lower rated fixed-income securities have greater volatility because there is less certainty that principal and interest payments will be made as scheduled. A portion of the Fund’s fixed-income securities may be rated below investment grade. 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. The Fund may be subject to certain liquidity risks that may result from the lack of an active market and the reduced number and capacity of traditional market participants to make a market in fixed-income securities.

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Credit and Interest Rate Risk. Credit risk refers to the possibility that the issuer or guarantor of a security will be unable or unwilling or perceived to be unable or unwilling to make interest payments and/or repay the principal on its debt. In such instances, the value of the Fund could decline and the Fund could lose money. Interest rate risk refers to the decline in the value of a fixed-income security resulting from changes in the general level of interest rates. When the general level of interest rates goes up, the prices of most fixed-income securities go down. When the general level of interest rates goes down, the prices of most fixed-income securities go up. The Fund may invest in variable and floating rate loans and other variable and floating rate securities. Although these instruments are generally less sensitive to interest rate changes than fixed rate instruments, the value of variable and floating rate loans and other securities may decline if their interest rates do not rise as quickly, or as much, as general interest rates. The Fund may face a heightened level of interest rate risk in times of monetary policy change and/or uncertainty, such as when the Federal Reserve Board adjusts a quantitative easing program and/or changes rates. A changing interest rate environment increases certain risks, including the potential for periods of volatility, increased redemptions, shortened durations (i.e., prepayment risk) and extended durations (i.e., extension risk). For example, during periods when interest rates are low, the Fund’s yield (and total return) also may be low or otherwise adversely affected or the Fund may be unable to maintain positive returns or minimize the volatility of the Fund’s net asset value per share. Credit ratings may not be an accurate assessment of liquidity or credit risk. Although credit ratings may not accurately reflect the true credit risk of an instrument, a change in the credit rating of an instrument or an issuer can have a rapid, adverse effect on the instrument’s liquidity and make it more difficult for the Fund to sell at an advantageous price or time.

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U.S. Government Securities. Different types of U.S. government securities are subject to different levels of credit risk, including the risk of default, depending on the nature of the particular government support for that security. For example, a U.S. government-sponsored entity, such as Federal National Mortgage Association or Federal Home Loan Mortgage Corporation, although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the U.S. Treasury and, therefore, are not backed by the full faith and credit of the United States. With respect to U.S. government securities that are not backed by the full faith and credit of the United States, there is the risk that the U.S. Government will not provide financial support to such U.S. government agencies, instrumentalities or sponsored enterprises if it is not obligated to do so by law.

Morgan Stanley Variable Investment Series | Fund Summary

Income Plus Portfolio (Con’t)

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Liquidity. The Fund may make investments that are 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. Liquidity risk may be magnified in a market where credit spread and interest rate volatility is rising and where investor redemptions from fixed-income mutual funds may be higher than normal. 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.

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High Yield Securities (“Junk Bonds”). The Fund’s investments in high yield securities expose it to a substantial degree of credit risk. Investing in emerging markets intensifies risk, because high yield securities may be more volatile in price in certain environments. High yield securities may be issued by companies that are restructuring, are smaller and less creditworthy or are more highly indebted than other companies, and therefore they may have more difficulty making scheduled payments of principal and interest. High yield securities are subject to greater risk of loss of income and principal than higher rated securities and may be considered speculative. High yield securities may experience reduced liquidity, and sudden and substantial decreases in price. An economic downturn affecting an issuer of high yield securities may result in an increased incidence of default. In the event of a default, the Fund may incur additional expenses to seek recovery.

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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks such as currency, political (including geopolitical), 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 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. 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 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 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, 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.

Morgan Stanley Variable Investment Series | Fund Summary

Income Plus Portfolio (Con’t)

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Loan-Related Investments. In addition to risks generally associated with debt investments, loan-related investments, such as public bank loans and loan participations and assignments, are subject to other risks. Such investments may be subject to additional risks including subordination to other creditors, no collateral or limited rights in collateral, lack of a regular trading market, extended settlement periods, liquidity risks, prepayment risks, potentially less protection under the federal securities laws and lack of publicly available information. Bank loans are subject to the risk of default in the payment of interest or principal on a loan, which will result in a reduction of income to the Fund, and a potential decrease in the Fund’s net asset value per share (“NAV”). The risk of default will increase in the event of an economic downturn or a substantial increase in interest rates. Because public bank loans usually rank lower in priority of payment to senior loans, they present a greater degree of investment risk. These bank loans may exhibit greater price volatility as well.

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Derivatives. Derivatives and other similar instruments often have risks similar to those of the underlying asset or instrument, including market risk, and may have additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivative transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss. Investments in currency derivatives may substantially change the Fund’s exposure to currency exchange rates and could result in losses to the Fund if currencies do not perform as the Adviser expects. Foreign currency forward exchange contracts and currency futures and options contracts create exposure to currencies in which the Fund’s securities are not denominated.

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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, social unrest, recessions, inflation, rapid interest rate changes and supply chain disruptions) 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.

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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.

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.

Past Performance

The following bar chart and table provide some indication of the risks of investing in the Fund by showing changes in the performance of the Fund’s Class X shares from year-to-year and by showing how the average annual returns of the Fund’s Class X shares for the past one, five and 10 year periods compare with those of a broad measure of market performance over time. This performance information does not include the impact of any charges deducted by your insurance company. If it did, returns would be lower. The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Annual Total Returns—Calendar Years

Morgan Stanley Variable Investment Series | Fund Summary

Income Plus Portfolio (Con’t)


High Quarter	06/30/20	10.50%
Low Quarter	06/30/22	-8.02%

Average Annual Total Returns

(for the calendar periods ended December 31, 2022)


	Past One Year	Past Five Years	Past Ten Years
Class X
Return before Taxes	-16.47%	0.19%	2.08%
Bloomberg U.S. Corporate Index (reflects no deduction for fees, expenses or taxes)¹	-15.76%	0.45%	1.96%

The Bloomberg U.S. Corporate Index is a broad-based benchmark that measures the investment grade, U.S. dollar-denominated, fixed rate, taxable corporate bond market. It includes U.S. dollar-denominated securities publicly issued by U.S. and non-U.S. industrial, utility and financial issuers that meet specified maturity, liquidity and quality requirements. It is not possible to invest directly in an index.

Fund Management

Adviser. Morgan Stanley Investment Management Inc.

Portfolio Managers. The Fund is managed by members of the Fixed Income team. Information about the members jointly and primarily responsible for the day-to-day management of the Fund is shown below:


Name	Title with Adviser	Date Began Managing Fund
Joseph Mehlman	Managing Director	November 2008
Angie Salam	Executive Director	July 2021
Stella Ma	Vice President	July 2022

Purchase and Sale of Fund Shares

The Prospectus offers Class X shares of the Income Plus Portfolio. The Fund also offers Class Y shares of the Fund through a separate prospectus. Class Y shares are subject to different expenses. For eligibility information, contact your insurance company.

The Fund offers its shares only to insurance company separate accounts that insurance companies establish to fund variable life insurance and/or variable annuity contracts. An insurance company purchases or redeems shares of the Fund based on, among other things, the amount of net contract premiums or purchase payments allocated to a separate account investment division, transfers to or from a separate account investment division, contract loans and repayments, contract withdrawals and surrenders, and benefit payments. The contract prospectus describes how contract owners may allocate, transfer and withdraw amounts to, and from, separate accounts.

For more information, please refer to the section of the Prospectus entitled “Shareholder Information—Purchases and Sales of Fund Shares.”

Tax Information

Special tax rules apply to life insurance companies, variable annuity and variable life insurance contracts. For information on federal income taxation of a life insurance company with respect to its receipt of distributions from the Fund and federal income taxation of owners of variable annuity or variable life insurance contracts, see the accompanying contract prospectus. For more information, please refer to the section of the Prospectus entitled “Shareholder Information—Taxes.”

Payments to Insurance Companies and Other Financial Intermediaries

If you purchase Fund shares through an insurance company or other financial intermediary (such as a bank), the Adviser and/or the Fund’s “Distributor,” Morgan Stanley Distribution, Inc., 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 insurance company or other financial intermediary and your salesperson to recommend one variable annuity contract over another or be a factor in an insurance company’s decision to include the Fund as an underlying investment option in its variable insurance products. Ask your salesperson or visit your insurance company’s or other financial intermediary’s web site for more information.

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