Morgan Stanley Finance LLC

March 2019

Preliminary Terms No. 1,640

Registration Statement Nos. 333-221595; 333-221595-01

Dated February 28, 2019

Filed pursuant to Rule 433

·   If the final index value is greater than or equal to the initial index value:

$10 + the greater of (i) $10 × the index percent change and (ii) the upside payment

·   If the final index value is less than the initial index value but is greater than or equal to the trigger level:

$10 + ($10 x absolute index return)

In this scenario, you will receive a 1% positive return on the securities for each 1% negative return on the underlying index. In no event will this amount exceed the stated principal amount plus $2.00.

·   If the final index value is less than the trigger level:

$10 × index performance factor

Under these circumstances, the payment at maturity will be less than the stated principal amount of $10, and will represent a loss of more than 20%, and possibly all, of your investment.

S&P 500^® Index

Daily Index Closing Values

January 1, 2014 to February 25, 2019

In the event that the maturity date is postponed due to postponement of the valuation date, the issuer shall give notice of such postponement and, once it has been determined, of the date to which the maturity date has been rescheduled (i) to each registered holder of the securities by mailing notice of such postponement by first class mail, postage prepaid, to such registered holder’s last address as it shall appear upon the registry books, (ii) to the trustee by facsimile confirmed by mailing such notice to the trustee by first class mail, postage prepaid, at its New York office and (iii) to The Depository Trust Company (the “depositary”) by telephone or facsimile, confirmed by mailing such notice to the depositary by first class mail, postage prepaid. Any notice that is mailed to a registered holder of the securities in the manner herein provided shall be conclusively presumed to have been duly given to such registered holder, whether or not such registered holder receives the notice. The issuer shall give such notice as promptly as possible, and in no case later than (i) with respect to notice of postponement of the maturity date, the business day immediately preceding the scheduled maturity date and (ii) with respect to notice of the date to which the maturity date has been rescheduled, the business day immediately following the actual valuation date for determining the final index value.

The issuer shall, or shall cause the calculation agent to, (i) provide written notice to the trustee and to the depositary of the amount of cash, if any, to be delivered with respect to the securities, on or prior to 10:30 a.m. (New York City time) on the business day preceding the maturity date, and (ii) deliver the aggregate cash amount, if any, due with respect to the securities to the trustee for delivery to the depositary, as holder of the securities, on the maturity date.

In 2007, the U.S. Treasury Department and the Internal Revenue Service (the “IRS”) released a notice requesting comments on the U.S. federal income tax treatment of “prepaid forward contracts” and similar instruments. The notice focuses in particular on whether to require holders of these instruments to accrue income over the term of their investment. It also asks for comments on a number of related topics, including the character of income or loss with respect to these instruments; whether short-term instruments should be subject to any such accrual regime; the relevance of factors such as the exchange-traded status of the instruments and the nature of the underlying property to which the instruments are linked; the degree, if any, to which income (including any mandated accruals) realized by non-U.S. investors should be subject to withholding tax; and whether these instruments are or should be subject to the “constructive ownership” rule, which very generally can operate to recharacterize certain long-term capital gain as ordinary income and impose an interest charge. While the notice requests comments on appropriate transition rules and effective dates, any Treasury regulations or other guidance promulgated after consideration of these issues could materially and adversely affect the tax consequences of an investment in the securities, possibly with retroactive effect.

As discussed in the accompanying product supplement for Jump Securities, Section 871(m) of the Internal Revenue Code of 1986, as amended, and Treasury regulations promulgated thereunder (“Section 871(m)”) generally impose a 30% (or a lower applicable treaty rate) withholding tax on dividend equivalents paid or deemed paid to Non-U.S. Holders with respect to certain financial instruments linked to U.S. equities or indices that include U.S. equities (each, an “Underlying Security”). Subject to certain exceptions, Section 871(m) generally applies to securities that substantially replicate the economic performance of one or more Underlying Securities, as determined based on tests set forth in the applicable Treasury regulations (a “Specified Security”). However, pursuant to an IRS notice, Section 871(m) will not apply to securities issued before January 1, 2021 that do not have a delta of one with respect to any Underlying Security. Based on the terms of the securities and current market conditions, we expect that the securities will not have a delta of one with respect to any Underlying Security on the pricing date. However, we will provide an updated determination in the final pricing supplement. Assuming that the securities do not have a delta of one with respect to any Underlying Security, our counsel is of the opinion that the securities should not be Specified Securities and, therefore, should not be subject to Section 871(m).

Our determination is not binding on the IRS, and the IRS may disagree with this determination. Section 871(m) is complex and its application may depend on your particular circumstances, including whether you enter into other transactions with respect to an Underlying Security. If withholding is required, we will not be required to pay any additional amounts with respect to the amounts so withheld. You should consult your tax adviser regarding the potential application of Section 871(m) to the securities.

Both U.S. and non-U.S. investors considering an investment in the securities should read the discussion under “Risk Factors” in this document and the discussion under “United States Federal Taxation” in the accompanying product supplement for Jump Securities and consult their tax advisers regarding all aspects of the U.S. federal income tax consequences of an investment in the securities, including possible alternative treatments, the issues presented by the aforementioned notice and any tax consequences arising under the laws of any state, local or non-U.S. taxing jurisdiction.

The discussion in the preceding paragraphs under “Tax considerations” and the discussion contained in the section entitled “United States Federal Taxation” in the accompanying product supplement for Jump Securities, insofar as they purport to describe provisions of U.S. federal income tax laws or legal conclusions with respect thereto, constitute the full opinion of Davis Polk & Wardwell LLP regarding the material U.S. federal tax consequences of an investment in the securities.

The proceeds from the sale of the securities will be used by us for general corporate purposes. We will receive, in aggregate, $10 per security issued, because, when we enter into hedging transactions in order to meet our obligations under the securities, our hedging counterparty will reimburse the cost of the agent’s commissions. The costs of the securities borne by you and described on page 2 above comprise the agent’s commissions and the cost of issuing, structuring and hedging the securities.

On or prior to the pricing date, we will hedge our anticipated exposure in connection with the securities by entering into hedging transactions with our affiliates and/or third-party dealers. We expect our hedging counterparties to take positions in the stocks constituting the underlying index and in futures and/or options contracts on the underlying index or its component stocks listed on major securities markets, or positions in any other available securities or instruments that they may wish to use in connection with such hedging. Such purchase activity could potentially increase the value of the underlying index on the pricing date, and, therefore, could increase the value at or above which the underlying index must close on the valuation date so that investors do not suffer a significant loss on their initial investment in the securities. In addition, through our affiliates, we are likely to modify our hedge position throughout the term of the securities, including on the valuation date, by purchasing and selling the stocks constituting the underlying index, futures or options contracts on the underlying index or its component stocks listed on major securities markets or positions in any other available securities or instruments that we may wish to use in connection with such hedging activities. As a result, these entities may be unwinding or adjusting hedge positions during the term of the securities, and the hedging strategy may involve greater and more frequent dynamic adjustments to the hedge as the valuation date approaches. We cannot give any assurance that our hedging activities will not affect the value of the underlying index, and, therefore, adversely affect the value of the securities or the payment you will receive at maturity, if any. For further information on our use of proceeds and hedging, see “Use of Proceeds and Hedging” in the accompanying product supplement.

Each fiduciary of a pension, profit-sharing or other employee benefit plan subject to Title I of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”) (a “Plan”), should consider the fiduciary standards of ERISA in the context of the Plan’s particular circumstances before authorizing an investment in the securities. Accordingly, among other factors, the fiduciary should consider whether the investment would satisfy the prudence and diversification requirements of ERISA and would be consistent with the documents and instruments governing the Plan.

In addition, we and certain of our affiliates, including MS & Co., may each be considered a “party in interest” within the meaning of ERISA, or a “disqualified person” within the meaning of the Internal Revenue Code of 1986, as amended (the “Code”), with respect to many Plans, as well as many individual retirement accounts and Keogh plans (such accounts and plans, together with other plans, accounts and arrangements subject to Section 4975 of the Code, also “Plans”). ERISA Section 406 and Code Section 4975 generally prohibit transactions between Plans and parties in interest or disqualified persons. Prohibited transactions within the meaning of ERISA or the Code would likely arise, for example, if the securities are acquired by or with the assets of a Plan with respect to which MS & Co. or any of its affiliates is a service provider or other party in interest, unless the securities are acquired pursuant to an exemption from the “prohibited transaction” rules. A violation of these “prohibited transaction” rules could result in an excise tax or other liabilities under ERISA and/or Section 4975 of the Code for those persons, unless exemptive relief is available under an applicable statutory or administrative exemption.

The U.S. Department of Labor has issued five prohibited transaction class exemptions (“PTCEs”) that may provide exemptive relief for direct or indirect prohibited transactions resulting from the purchase or holding of the securities. Those class exemptions are PTCE 96-23 (for certain transactions determined by in-house asset managers), PTCE 95-60 (for certain transactions involving insurance company general accounts), PTCE 91-38 (for certain transactions involving bank collective investment funds), PTCE 90-1 (for certain transactions involving insurance company separate accounts) and PTCE 84-14 (for certain transactions determined by independent qualified professional asset managers). In addition, ERISA Section 408(b)(17) and Section 4975(d)(20) of the Code provide an exemption for the purchase and sale of securities and the related lending transactions, provided that neither the issuer of the securities nor any of its affiliates has or exercises any discretionary authority or control or renders any investment advice with respect to the assets of the Plan involved in the transaction and provided further that the Plan pays no more, and receives no less, than “adequate consideration” in connection with the transaction (the so-called “service provider” exemption). There can be no assurance that any of these class or statutory exemptions will be available with respect to transactions involving the securities.

Because we may be considered a party in interest with respect to many Plans, the securities may not be purchased, held or disposed of by any Plan, any entity whose underlying assets include “plan assets” by reason of any Plan’s investment in the entity (a “Plan Asset Entity”) or any person investing “plan assets” of any Plan, unless such purchase, holding or disposition is eligible for exemptive relief, including relief available under PTCEs 96-23, 95-60, 91-38, 90-1, 84-14 or the service provider exemption or such purchase, holding or disposition is otherwise not prohibited. Any purchaser, including any fiduciary purchasing on behalf of a Plan, transferee or holder of the securities will be

deemed to have represented, in its corporate and its fiduciary capacity, by its purchase and holding of the securities that either (a) it is not a Plan or a Plan Asset Entity and is not purchasing such securities on behalf of or with “plan assets” of any Plan or with any assets of a governmental, non-U.S. or church plan that is subject to any federal, state, local or non-U.S. law that is substantially similar to the provisions of Section 406 of ERISA or Section 4975 of the Code (“Similar Law”) or (b) its purchase, holding and disposition of these securities will not constitute or result in a non-exempt prohibited transaction under Section 406 of ERISA or Section 4975 of the Code or violate any Similar Law.

Due to the complexity of these rules and the penalties that may be imposed upon persons involved in non-exempt prohibited transactions, it is particularly important that fiduciaries or other persons considering purchasing the securities on behalf of or with “plan assets” of any Plan consult with their counsel regarding the availability of exemptive relief.

The securities are contractual financial instruments. The financial exposure provided by the securities is not a substitute or proxy for, and is not intended as a substitute or proxy for, individualized investment management or advice for the benefit of any purchaser or holder of the securities. The securities have not been designed and will not be administered in a manner intended to reflect the individualized needs and objectives of any purchaser or holder of the securities.

Each purchaser or holder of any securities acknowledges and agrees that:

(i)   the purchaser or holder or its fiduciary has made and shall make all investment decisions for the purchaser or holder and the purchaser or holder has not relied and shall not rely in any way upon us or our affiliates to act as a fiduciary or adviser of the purchaser or holder with respect to (A) the design and terms of the securities, (B) the purchaser or holder’s investment in the securities, or (C) the exercise of or failure to exercise any rights we have under or with respect to the securities;

(ii)  we and our affiliates have acted and will act solely for our own account in connection with (A) all transactions relating to the securities and (B) all hedging transactions in connection with our obligations under the securities;

(iii)  any and all assets and positions relating to hedging transactions by us or our affiliates are assets and positions of those entities and are not assets and positions held for the benefit of the purchaser or holder;

(iv)  our interests are adverse to the interests of the purchaser or holder; and

(v)   neither we nor any of our affiliates is a fiduciary or adviser of the purchaser or holder in connection with any such assets, positions or transactions, and any information that we or any of our affiliates may provide is not intended to be impartial investment advice.

Each purchaser and holder of the securities has exclusive responsibility for ensuring that its purchase, holding and disposition of the securities do not violate the prohibited transaction rules of ERISA or the Code or any Similar Law. The sale of any securities to any Plan or plan subject to Similar Law is in no respect a representation by us or any of our affiliates or representatives that such an investment meets all relevant legal requirements with respect to investments by plans generally or any particular plan, or that such an investment is appropriate for plans generally or any particular plan. In this regard, neither this discussion nor anything provided in this document is or is intended to be investment advice directed at any potential Plan purchaser or at Plan purchasers generally and such purchasers of these securities should consult and rely on their own counsel and advisers as to whether an investment in these securities is suitable.

However, individual retirement accounts, individual retirement annuities and Keogh plans, as well as employee benefit plans that permit participants to direct the investment of their accounts, will not be permitted to purchase or hold the securities if the account, plan or annuity is for the benefit of an employee of Morgan Stanley, Morgan Stanley Wealth Management or a family member and the employee receives any compensation (such as, for example, an addition to bonus) based on the purchase of the securities by the account, plan or annuity.

The agent may distribute the securities through Morgan Stanley Smith Barney LLC (“Morgan Stanley Wealth Management”), as selected dealer, or other dealers, which may include Morgan Stanley & Co. International plc (“MSIP”) and Bank Morgan Stanley AG. Morgan Stanley Wealth Management, MSIP and Bank Morgan Stanley AG are affiliates of ours. Selected dealers, including Morgan Stanley Wealth Management, and their financial advisors will collectively receive from the agent, Morgan Stanley & Co. LLC, a fixed sales commission of $0.30 for each security they sell. In addition, Morgan Stanley Wealth Management will receive a structuring fee of $0.05 for each security.

MS & Co. is an affiliate of MSFL and a wholly owned subsidiary of Morgan Stanley, and it and other affiliates of ours expect to make a profit by selling, structuring and, when applicable, hedging the

securities. When MS & Co. prices this offering of securities, it will determine the economic terms of the securities such that for each security the estimated value on the pricing date will be no lower than the minimum level described in “Investment Summary” beginning on page 2.

MS & Co. will conduct this offering in compliance with the requirements of FINRA Rule 5121 of the Financial Industry Regulatory Authority, Inc., which is commonly referred to as FINRA, regarding a FINRA member firm’s distribution of the securities of an affiliate and related conflicts of interest. MS & Co. or any of our other affiliates may not make sales in this offering to any discretionary account. See “Plan of Distribution (Conflicts of Interest)” and “Use of Proceeds and Hedging” in the accompanying product supplement.

MSFL and Morgan Stanley have filed a registration statement (including a prospectus, as supplemented by the product supplement for Jump Securities and the index supplement) with the Securities and Exchange Commission, or SEC, for the offering to which this communication relates. You should read the prospectus in that registration statement, the product supplement for Jump Securities, the index supplement and any other documents relating to this offering that MSFL and Morgan Stanley have filed with the SEC for more complete information about MSFL, Morgan Stanley and this offering. You may get these documents without cost by visiting EDGAR on the SEC web site at.www.sec.gov. Alternatively, MSFL and/or Morgan Stanley will arrange to send you the prospectus, the product supplement for Jump Securities and the index supplement if you so request by calling toll-free 800-584-6837.

You may access these documents on the SEC web site at www.sec.gov.as follows:

Product Supplement for Jump Securities dated November 16, 2017

Index Supplement dated November 16, 2017

Prospectus dated November 16, 2017

Terms used but not defined in this document are defined in the product supplement for Jump Securities, in the index supplement or in the prospectus.