Primary Offering Prospectus (Form 424B2)

Pricing Supplement No. 12,786

Registration Statement Nos. 333-275587; 333-275587-01

Dated January 9, 2026

Filed pursuant to Rule 424(b)(2)

Morgan Stanley Finance LLC

Structured Investments

Jump Notes with Auto-Callable Feature due January 12, 2029

Based on the Performance of the iShares® iBoxx® $ High Yield Corporate Bond ETF

Fully and Unconditionally Guaranteed by Morgan Stanley

￭The notes are unsecured obligations of Morgan Stanley Finance LLC ("MSFL") and are fully and unconditionally guaranteed by Morgan Stanley. The notes will pay no interest and have the terms described in the accompanying product supplement and prospectus, as supplemented or modified by this document.

￭Automatic early redemption. The notes will be automatically redeemed if the closing level of the underlier is greater than or equal to the call threshold level on any determination date (other than the final determination date) for an early redemption payment that will increase over the term of the notes. No further payments will be made on the notes once they have been automatically redeemed.

￭Payment at maturity. If the notes have not been automatically redeemed prior to maturity and the final level is greater than or equal to the initial level, investors will receive a fixed positive return at maturity. If, however, the final level is less than the initial level, investors will receive only the stated principal amount at maturity.

￭The notes are for investors who are concerned about principal risk and who are willing to forgo current income in exchange for the repayment of principal at maturity and the possibility of receiving an early redemption payment or payment at maturity that exceeds the stated principal amount. You will not participate in any appreciation of the underlier. The notes are notes issued as part of MSFL's Series A Global Medium-Term Notes program.

￭All payments are subject to our credit risk. If we default on our obligations, you could lose some or all of your investment. These notes are not secured obligations and you will not have any security interest in, or otherwise have any access to, any underlying reference asset or assets.

(1)The notes will be sold only to investors purchasing the notes in fee-based advisory accounts.

(2)MS & Co. expects to sell all of the notes that it purchases from us to an unaffiliated dealer at a price of $1,000 per note, for further sale to certain fee-based advisory accounts at the price to public of $1,000 per note. MS & Co. will not receive a sales commission with respect to the notes. See "Supplemental information regarding plan of distribution; conflicts of interest." For additional information, see "Plan of Distribution (Conflicts of Interest)" in the accompanying product supplement.

(3)See "Use of Proceeds and Hedging" in the accompanying product supplement.

The notes involve risks not associated with an investment in ordinary debt securities. See "Risk Factors" beginning on page 6.

The Securities and Exchange Commission and state securities regulators have not approved or disapproved these notes, or determined if this document or the accompanying product supplement and prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The notes are not deposits or savings accounts and are not insured by the Federal Deposit Insurance Corporation or any other governmental agency or instrumentality, nor are they obligations of, or guaranteed by, a bank.

You should read this document together with the related product supplement and prospectus, each of which can be accessed via the hyperlinks below. Please also see "Additional Terms of the Notes" and "Additional Information About the Notes" at the end of this document.

References to "we," "us" and "our" refer to Morgan Stanley or MSFL, or Morgan Stanley and MSFL collectively, as the context requires.

Product Supplementfor Notesdated February 7, 2025 Prospectus dated April 12, 2024

Morgan Stanley Finance LLC

Determination Dates, Early Redemption Dates and Early Redemption Payments

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Estimated Value of the Notes

The original issue price of each note is $1,000. This price includes costs associated with issuing, selling, structuring and hedging the notes, which are borne by you, and, consequently, the estimated value of the notes on the pricing date is less than $1,000. Our estimate of the value of the notes as determined on the pricing date is set forth on the cover of this document.

What goes into the estimated value on the pricing date?

In valuing the notes on the pricing date, we take into account that the notes comprise both a debt component and a performance-based component linked to the underlier. The estimated value of the notes is determined using our own pricing and valuation models, market inputs and assumptions relating to the underlier, instruments based on the underlier, volatility and other factors including current and expected interest rates, as well as an interest rate related to our secondary market credit spread, which is the implied interest rate at which our conventional fixed rate debt trades in the secondary market.

What determines the economic terms of the notes?

In determining the economic terms of the notes, we use an internal funding rate, which is likely to be lower than our secondary market credit spreads and therefore advantageous to us. If the issuing, selling, structuring and hedging costs borne by you were lower or if the internal funding rate were higher, one or more of the economic terms of the notes would be more favorable to you.

What is the relationship between the estimated value on the pricing date and the secondary market price of the notes?

The price at which MS & Co. purchases the notes in the secondary market, absent changes in market conditions, including those related to the underlier, may vary from, and be lower than, the estimated value on the pricing date, because the secondary market price takes into account our secondary market credit spread as well as the bid-offer spread that MS & Co. would charge in a secondary market transaction of this type and other factors. However, because the costs associated with issuing, selling, structuring and hedging the notes are not fully deducted upon issuance, to the extent that MS & Co. may buy or sell the notes in the secondary market during the amortization period specified herein, absent changes in market conditions, including those related to the underlier, and to our secondary market credit spreads, it would do so based on values higher than the estimated value. We expect that those higher values will also be reflected in your brokerage account statements.

MS & Co. may, but is not obligated to, make a market in the notes, and, if it once chooses to make a market, may cease doing so at any time.

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Hypothetical Examples

The following hypothetical examples illustrate how to determine whether the notes will be automatically redeemed with respect to a determination date and how to calculate the payment at maturity if the notes have not been automatically redeemed prior to maturity. The following examples are for illustrative purposes only. Whether the notes are automatically redeemed prior to maturity will be determined by reference to the closing level of the underlier on each determination date. The payment at maturity will be determined by reference to the closing level of the underlier on the final determination date. The actual initial level and call threshold level were determined on the strike date. All payments on the notes are subject to our credit risk. The numbers in the hypothetical examples below may have been rounded for ease of analysis. The below examples are based on the following terms:

*The hypothetical initial level of $100.00 for the underlier has been chosen for illustrative purposes only and does not represent the actual initial level of the underlier. Please see "Historical Information" below for historical data regarding the actual closing levels of the underlier.

How to determine whether the notes will be automatically redeemed with respect to a determination date:

On hypothetical determination date #1, because the closing level of the underlier is less than the call threshold level, the notes are not automatically redeemed on the related early redemption date.

On hypothetical determination date #2, because the closing level of the underlier is greater than or equal to the call threshold level, the notes are automatically redeemed on the related early redemption date for an early redemption payment corresponding to a return of approximately 7.00% per annum. No further payments are made on the notes once they have been automatically redeemed.

If the closing level of the underlier is less than the call threshold level on each determination date, the notes will not be automatically redeemed prior to maturity.

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How to calculate the payment at maturity (if the notes have not been automatically redeemed):

The hypothetical examples below illustrate how to calculate the payment at maturity if the notes have not been automatically redeemed prior to maturity.

In example #1, the final level is greater than or equal to the initial level. Therefore, investors receive at maturity a payment corresponding to a return of approximately 7.00% per annum. Investors do not participate in any appreciation of the underlier.

In example #2, the final level is less than the initial level. Therefore, investors receive at maturity the stated principal amount.

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Risk Factors

This section describes the material risks relating to the notes. For further discussion of these and other risks, you should read the section entitled "Risk Factors" in the accompanying product supplement and prospectus. We also urge you to consult with your investment, legal, tax, accounting and other advisers in connection with your investment in the notes.

Risks Relating to an Investment in the Notes

￭The notes may not pay more than the stated principal amount at maturity. If the notes have not been automatically redeemed prior to maturity and the final level is less than the initial level, you will receive only the stated principal amount at maturity, and you will not receive a positive return on your investment.

￭The notes do not pay interest. Because the notes do not pay interest, if the notes have not been automatically redeemed prior to maturity and the final level is less than the initial level, you will not receive a positive return on your investment, and therefore the overall return on the notes (the effective yield to maturity) will be less than the amount that would be paid on an ordinary debt security. Accordingly, the return of only the stated principal amount at maturity will not compensate you for the effects of inflation and other factors relating to the value of money over time.

￭The appreciation potential of the notes is limited by the fixed early redemption payment or payment at maturity specified for each determination date. The appreciation potential of the notes is limited by the applicable fixed early redemption payment or payment at maturity, as applicable, payable only if the closing level of the underlier is greater than or equal to the call threshold level on the related determination date. In all cases, you will not participate in any appreciation of the underlier, which could be significant.

￭The notes are subject to early redemption risk. The term of your investment in the notes may be shortened due to the automatic early redemption feature of the notes. If the notes are automatically redeemed prior to maturity, you will receive no further payments on the notes, may be forced to invest in a lower interest rate environment and may not be able to reinvest at comparable terms or returns. However, under no circumstances will the notes be redeemed prior to the first determination date.

￭The market price of the notes may be influenced by many unpredictable factors. Several factors, many of which are beyond our control, will influence the value of the notes in the secondary market and the price at which MS & Co. may be willing to purchase or sell the notes in the secondary market. We expect that generally the value of the underlier at any time will affect the value of the notes more than any other single factor. Other factors that may influence the value of the notes include:

othe volatility (frequency and magnitude of changes in value) of the underlier;

ointerest and yield rates in the market;

odividend rates on the underlier;

ogeopolitical conditions and economic, financial, political, regulatory or judicial events that affect the underlier or equity markets generally;

othe availability of comparable instruments;

othe occurrence of certain events affecting the underlier that may or may not require an adjustment to the adjustment factor;

othe composition of the underlier and changes in the component securities of the underlier;

othe time remaining until the notes mature; and

oany actual or anticipated changes in our credit ratings or credit spreads.

Some or all of these factors will influence the price that you will receive if you sell your notes prior to maturity. Generally, the longer the time remaining to maturity, the more the market price of the notes will be affected by the other factors described above. For example, you may have to sell your notes at a substantial discount from the stated principal amount if, at the time of sale, the closing level of the underlier is at, below or not sufficiently above the initial level, or if market interest rates rise.

You can review the historical closing levels of the underlier in the section of this document called "Historical Information." You cannot predict the future performance of the underlier based on its historical performance. The value of the underlier may be, and has recently been, volatile, and we can give you no assurance that the volatility will lessen. There can be no assurance that the closing level of the underlier will be greater than or equal to the call threshold level on any determination date, or that the final level will be greater than or equal to the initial level, so that you will receive a payment on the notes that exceeds the stated principal amount of the notes.

￭The notes are subject to our credit risk, and any actual or anticipated changes to our credit ratings or credit spreads may adversely affect the market value of the notes. You are dependent on our ability to pay all amounts due on the notes, and, therefore, you are subject to our credit risk. The notes are not guaranteed by any other entity. If we default on our obligations under the notes, your investment would be at risk and you could lose some or all of your investment. As a result, the market value of the notes prior to maturity will be affected by changes in the market's view of our creditworthiness. Any actual or anticipated decline in

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our credit ratings or increase in the credit spreads charged by the market for taking our credit risk is likely to adversely affect the market value of the notes.

￭As a finance subsidiary, MSFL has no independent operations and will have no independent assets. As a finance subsidiary, MSFL has no independent operations beyond the issuance and administration of its securities and will have no independent assets available for distributions to holders of MSFL securities if they make claims in respect of such securities in a bankruptcy, resolution or similar proceeding. Accordingly, any recoveries by such holders will be limited to those available under the related guarantee by Morgan Stanley and that guarantee will rank pari passu with all other unsecured, unsubordinated obligations of Morgan Stanley. Holders will have recourse only to a single claim against Morgan Stanley and its assets under the guarantee. Holders of securities issued by MSFL should accordingly assume that in any such proceedings they would not have any priority over and should be treated pari passu with the claims of other unsecured, unsubordinated creditors of Morgan Stanley, including holders of Morgan Stanley-issued securities.

￭The rate we are willing to pay for securities of this type, maturity and issuance size is likely to be lower than the rate implied by our secondary market credit spreads and advantageous to us. Both the lower rate and the inclusion of costs associated with issuing, selling, structuring and hedging the notes in the original issue price reduce the economic terms of the notes, cause the estimated value of the notes to be less than the original issue price and will adversely affect secondary market prices. Assuming no change in market conditions or any other relevant factors, the prices, if any, at which dealers, including MS & Co., may be willing to purchase the notes in secondary market transactions will likely be significantly lower than the original issue price, because secondary market prices will exclude the issuing, selling, structuring and hedging-related costs that are included in the original issue price and borne by you and because the secondary market prices will reflect our secondary market credit spreads and the bid-offer spread that any dealer would charge in a secondary market transaction of this type as well as other factors.

The inclusion of the costs of issuing, selling, structuring and hedging the notes in the original issue price and the lower rate we are willing to pay as issuer make the economic terms of the notes less favorable to you than they otherwise would be.

However, because the costs associated with issuing, selling, structuring and hedging the notes are not fully deducted upon issuance, to the extent that MS & Co. may buy or sell the notes in the secondary market during the amortization period specified herein, absent changes in market conditions, including those related to the underlier, and to our secondary market credit spreads, it would do so based on values higher than the estimated value, and we expect that those higher values will also be reflected in your brokerage account statements.

￭The estimated value of the notes is determined by reference to our pricing and valuation models, which may differ from those of other dealers and is not a maximum or minimum secondary market price. These pricing and valuation models are proprietary and rely in part on subjective views of certain market inputs and certain assumptions about future events, which may prove to be incorrect. As a result, because there is no market-standard way to value these types of securities, our models may yield a higher estimated value of the notes than those generated by others, including other dealers in the market, if they attempted to value the notes. In addition, the estimated value on the pricing date does not represent a minimum or maximum price at which dealers, including MS & Co., would be willing to purchase your notes in the secondary market (if any exists) at any time. The value of your notes at any time after the date of this document will vary based on many factors that cannot be predicted with accuracy, including our creditworthiness and changes in market conditions. See also "The market price of the notes may be influenced by many unpredictable factors" above.

￭The notes will not be listed on any securities exchange and secondary trading may be limited. The notes will not be listed on any securities exchange. Therefore, there may be little or no secondary market for the notes. MS & Co. may, but is not obligated to, make a market in the notes and, if it once chooses to make a market, may cease doing so at any time. When it does make a market, it will generally do so for transactions of routine secondary market size at prices based on its estimate of the current value of the notes, taking into account its bid/offer spread, our credit spreads, market volatility, the notional size of the proposed sale, the cost of unwinding any related hedging positions, the time remaining to maturity and the likelihood that it will be able to resell the notes. Even if there is a secondary market, it may not provide enough liquidity to allow you to trade or sell the notes easily. Since other broker-dealers may not participate significantly in the secondary market for the notes, the price at which you may be able to trade your notes is likely to depend on the price, if any, at which MS & Co. is willing to transact. If, at any time, MS & Co. were to cease making a market in the notes, it is likely that there would be no secondary market for the notes. Accordingly, you should be willing to hold your notes to maturity.

￭As discussed in more detail in the accompanying product supplement, investing in the notes is not equivalent to investing in the underlier(s).

￭You may be required to recognize taxable income on the notes prior to maturity. If you are a U.S. investor in a note, under the treatment of a note as a contingent payment debt instrument, you will generally be required to recognize taxable interest income in each year that you hold the note. In addition, any gain you recognize under the rules applicable to contingent payment debt instruments will generally be treated as ordinary interest income rather than capital gain. You should review carefully the section entitled "United States Federal Income Tax Considerations" herein, in combination with the section entitled "United States

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Federal Income Tax Considerations" in the accompanying product supplement, and consult your tax adviser regarding the U.S. federal income tax consequences of an investment in the notes.

Risks Relating to the Underlier(s)

￭Because your return on the notes will depend upon the performance of the underlier(s), the notes are subject to the following risk(s), as discussed in more detail in the accompanying product supplement.

oAdjustments to an underlying fund or the index tracked by such underlying fund could adversely affect the value of the notes.

oThe performance and market price of an underlying fund, particularly during periods of market volatility, may not correlate with the performance of its share underlying index, the performance of the component securities of its share underlying index or the net asset value per share of such underlying fund.

oThe anti-dilution adjustments the calculation agent is required to make do not cover every event that could affect an underlying fund.

￭The notes are subject to interest rate-related risks and credit-related risks. The iShares® iBoxx® $ High Yield Corporate Bond ETF invests in U.S. dollar-denominated fixed-income securities. However, the performance of the iShares® iBoxx® $ High Yield Corporate Bond ETF will reflect only changes in the market prices of the bonds held by the iShares® iBoxx® $ High Yield Corporate Bond ETF and will not reflect interest payments on these bonds. As a result, the performance of the iShares® iBoxx® $ High Yield Corporate Bond ETF will be less, and perhaps significantly less, than the return that would be realized by a direct investment in the iShares® iBoxx® $ High Yield Corporate Bond ETF. The market prices of the bonds held by the iShares® iBoxx® $ High Yield Corporate Bond ETF are volatile and will be significantly influenced by a number of factors, particularly the yields on these bonds as compared to current market interest rates and the actual or perceived credit quality of the issuers of these bonds.

In general, the value of bonds is significantly affected by changes in current market interest rates. As interest rates rise, the prices of bonds, including those held by the iShares® iBoxx® $ High Yield Corporate Bond ETF, are likely to decrease. Securities with longer durations tend to be more sensitive to interest rate changes, usually making them more volatile than securities with shorter durations. As a result, rising interest rates will likely cause the value of the bonds held by the iShares® iBoxx® $ High Yield Corporate Bond ETF and the value of the notes to decline, possibly significantly.

Interest rates are subject to volatility due to a variety of factors, including:

osentiment regarding underlying strength in the U.S. economy and global economies;

oexpectations regarding the level of price inflation;

osentiment regarding credit quality in the U.S. and global credit markets;

ocentral bank policies regarding interest rates; and

othe performance of U.S. and foreign capital markets.

In addition, the prices of the bonds held by the iShares® iBoxx® $ High Yield Corporate Bond ETF are significantly influenced by the creditworthiness of the issuers of those bonds. The issuers of the bonds held by bond ETFs may have their credit ratings downgraded or their credit spreads may widen significantly. Following a ratings downgrade by any credit rating agency or the widening of credit spreads, some or all of the bonds may suffer significant and rapid price declines. The prices of high yield bonds such as those held by the iShares® iBoxx® $ High Yield Corporate Bond ETF are likely to be particularly susceptible to rapid declines during a period of economic uncertainty or crisis.

Risks Relating to Conflicts of Interest

In engaging in certain activities described below and as discussed in more detail in the accompanying product supplement, our affiliates may take actions that may adversely affect the value of and your return on the notes, and in so doing they will have no obligation to consider your interests as an investor in the notes.

￭The calculation agent, which is a subsidiary of Morgan Stanley and an affiliate of MSFL, will make determinations with respect to the notes. As calculation agent, MS & Co. will make any determinations necessary to calculate any payment(s) on the notes. Moreover, certain determinations made by MS & Co., in its capacity as calculation agent, may require it to exercise discretion and make subjective judgments, which may adversely affect your return on the notes. In addition, MS & Co. has determined the estimated value of the notes on the pricing date.

￭Hedging and trading activity by our affiliates could potentially adversely affect the value of the notes.

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Historical Information

iShares® iBoxx® $ High Yield Corporate Bond ETF Overview

Bloomberg Ticker Symbol: HYG UP

The iShares® iBoxx® $ High Yield Corporate Bond ETF seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of its share underlying index, which is the Markit iBoxx® USD Liquid High Yield Index. The underlying fund managers with respect to the iShares® iBoxx® $ High Yield Corporate Bond ETF are iShares Trust and BlackRock Fund Advisors, which are registered investment companies. It is possible that the underlier may not fully replicate the performance of its share underlying index due to the temporary unavailability of certain securities in the secondary market or due to other extraordinary circumstances. Information provided to or filed with the Securities and Exchange Commission by the underlying fund manager pursuant to the Securities Act of 1933 and the Investment Company Act of 1940 can be located by reference to Securities and Exchange Commission file numbers 333-92935 and 811-09729, respectively, through the Securities and Exchange Commission's website at www.sec.gov. In addition, information regarding the underlier may be obtained from other sources including, but not limited to, press releases, newspaper articles and other publicly disseminated documents. Neither we nor the agent makes any representation that such publicly available documents or any other publicly available information regarding the underlier is accurate or complete.

The closing level of the underlier on January 9, 2026 was $81.00. The following graph sets forth the daily closing levels of the underlier for the period noted below. We obtained the historical information presented in this document from Bloomberg Financial Markets, without independent verification. The underlier has at times experienced periods of high volatility. You should not take the historical closing levels of the underlier as an indication of its future performance, and no assurance can be given as to the closing level of the underlier at any time.

This document relates only to the notes referenced hereby and does not relate to the underlier. We have derived all disclosures contained in this document regarding the underlier from the publicly available documents described above. In connection with this offering of notes, neither we nor the agent has participated in the preparation of such documents or made any due diligence inquiry with respect to the underlier. Neither we nor the agent makes any representation that such publicly available documents or any other publicly available information regarding the underlier is accurate or complete. Furthermore, we cannot give any assurance that all events occurring prior to the date hereof (including events that would affect the accuracy or completeness of the publicly available documents described above) that would affect the trading price of the underlier (and therefore the closing level of the underlier on the strike date) have been publicly disclosed. Subsequent disclosure of any such events or the disclosure of or failure to disclose material future events concerning the underlier could affect the value received with respect to the notes and therefore the value of the notes.

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Neither we nor any of our affiliates makes any representation to you as to the performance of the underlier.

We and/or our affiliates may presently or from time to time engage in business with the underlying fund manager. In the course of such business, we and/or our affiliates may acquire non-public information with respect to the underlier, and neither we nor any of our affiliates undertakes to disclose any such information to you. In addition, one or more of our affiliates may publish research reports with respect to the underlier. The statements in the preceding two sentences are not intended to affect the rights of investors in the notes under the securities laws. You should undertake an independent investigation of the underlier as in your judgment is appropriate to make an informed decision with respect to an investment linked to the underlier.

The notes are not sponsored, endorsed, sold, or promoted by the underlying fund manager. The underlying fund manager makes no representations or warranties to the owners of the notes or any member of the public regarding the advisability of investing in the notes. The underlying fund manager has no obligation or liability in connection with the operation, marketing, trading or sale of the notes.

Markit iBoxx® USD Liquid High Yield Index. The Markit iBoxx® USD Liquid High Yield Index is a market value weighted index calculated, published and disseminated daily by Markit Indices Limited. The index is designed to provide a broad representation of the U.S. dollar-denominated liquid high yield corporate bond market. The share underlying index publisher with respect to the Markit iBoxx® USD Liquid High Yield Index is Markit Indices Limited, or any successor thereof.

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Additional Terms of the Notes

Please read this information in conjunction with the terms on the cover of this document.

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Additional Information About the Notes

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