Enhanced Barrier Digital Plus Securities (C) — Barrier‑linked, capped upside notes

Rhea-AI Filing Summary

Citigroup Global Markets Holdings Inc. offers Enhanced Barrier Digital Plus Securities, unsecured debt securities guaranteed by Citigroup Inc., whose maturity payoff depends on an underlying asset’s performance and certain terms such as a Digital Return, Final Barrier Level, Upside Participation Rate and a Maximum Return. These securities do not pay periodic interest or dividends and expose investors to issuer credit risk; they typically mature between 12 months and 5 years. Specific terms for any offering will appear in a pricing supplement, and investors should read the applicable product supplement, prospectus supplement and prospectus before investing.

Insights

Structured Products Specialist

These are credit‑exposed, barrier‑linked notes with capped upside and contingent principal protection.

Enhanced Barrier Digital Plus Securities pay at maturity based solely on the underlying’s final value relative to a Final Barrier Level and may provide a fixed Digital Return if the barrier condition is met. Upside is limited by a stated Maximum Return and may include an Upside Participation Rate.

The securities do not pay interest or dividends and are unsecured obligations of the issuer and guarantor, so credit deterioration of either entity is the primary counterparty risk. Pricing supplements set definitive terms; review those for barrier levels, digital amounts, caps and maturity.

Tax & Legal Advisor

U.S. federal tax treatment is uncertain; consultation recommended.

The materials state there is no direct IRS authority on tax treatment and Citi will not seek a ruling. Depending on terms, gain or loss generally should be long‑term capital if held >1 year, but the issuer disclaims assurance the IRS will agree.

Investors should obtain tax advice and review the offering documents for the specific product's tax discussion before investing.

The securities discussed by this product summary supplement are unsecured debt securities issued by Citigroup Global Markets Holdings Inc. and guaranteed by Citigroup Inc. Thus all payments on the securities are subject to the credit risk of Citigroup Global Markets Holdings Inc. and Citigroup Inc. The securities are not bank deposits and are not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency, nor are they obligations of, or guaranteed by, a bank. Investing in the securities involves risks not associated with an investment in conventional debt securities. See “Key risks associated with Enhanced Barrier Digital Plus Securities” beginning on page 3 and the accompanying Product Supplement. The securities will not be listed on any securities exchange.

The information in this product summary supplement is not complete and may be changed. This product summary supplement is not an offer to sell these securities and it is not soliciting an offer to buy the securities in any jurisdiction where the offer or sale is not permitted. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities or determined that this product summary supplement and the accompanying product supplement, prospectus supplement and prospectus are truthful or complete. Any representation to the contrary is a criminal offense. The product supplement, prospectus supplement and prospectus referenced below contain certain general terms of Enhanced Barrier Digital Plus Securities. The specific terms of any offering of Enhanced Barrier Digital Plus Securities will be set forth in a pricing supplement for that offering, which may add, update or modify any information in this document or the product supplement, prospectus supplement or prospectus. If any information in the applicable pricing supplement is inconsistent with the other offering documents, including this document, you should rely on the information in that pricing supplement. You should read the applicable pricing supplement together with the product supplement, prospectus supplement and prospectus before making a decision to invest in any Enhanced Barrier Digital Plus Security. You may access the product supplement, prospectus supplement and prospectus on the SEC website at www.sec.gov as follows: Product Supplement No. ES-01-11 dated February 25, 2026 Prospectus Supplement and Prospectus each dated February 25, 2026

Enhanced Barrier Digital Plus Securities Citigroup Global Markets Holdings Inc. March 5, 2026 Filed Pursuant to Rule 424(b)(2) Registration Statement Nos. 333 - 293732 an d 333 - 293732 - 02 The securities discussed by this product summary supplement are unsecured debt securities issued by Citigroup Global Markets Holdings Inc. and guaranteed by Citigroup Inc. Thus all payments on the securities are subject to the credit risk of Citigroup Global Markets Holdings Inc. and Citigroup Inc. The securities are not bank deposits and are not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency, nor are they obligations of, or guaranteed by, a bank. Investing in the securities involves risks not associated with an investment in conventional debt securities. See “Key risks associated with Enhanced Barrier Digital Plus Securities ” beginning on page 3 and the accompanying Product Supplement. The securities will not be listed on any securities exchange. The information in this product summary supplement is not complete and may be changed. This product summary supplement is not an offer to sell these securities and it is not soliciting an offer to buy the securities in any jurisdiction where the offer or sale is not permitted. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities or determined that this product summary supplement and the accompanying product supplement, prospectus supplement and prospectus are truthful or complete. Any representation to the contrary is a criminal offense. The product supplement, prospectus supplement and prospectus referenced below contain certain general terms of Enhanced Barrier Digital Plus Securities . The specific terms of any offering of Enhanced Barrier Digital Plus Securities will be set forth in a pricing supplement for that offering, which may add, update or modify any information in this document or the product supplement, prospectus supplement or prospectus. If any information in the applicable pricing supplement is inconsistent with the other offering documents, including this document, you should rely on the information in that pricing supplement. You should read the applicable pricing supplement together with the product supplement, prospectus supplement and prospectus before making a decision to invest in any Enhanced Barrier Digital Plus Security . You may access the product supplement, prospectus supplement and prospectus on the SEC website at www.sec.gov as follows: Product Supplement No. ES - 01 - 11 dated February 25, 2026 Prospectus Supplement and Prospectus each dated February 25, 2026 A Guide for Investors

Citigroup Global Markets Holdings Inc. 2 What are Enhanced Barrier Digital Plus Securities ? Enhanced Barrier Digital Plus Securities are unsecured debt securities of the issuer, but unlike conventional debt, the securities do not pay interest and do not return a fixed amount of principal at maturity. Instead, Enhanced Barrier Digital Plus Securities offer a payment at maturity that may be greater than or less than the principal amount, depending on the performance of an “underlying” asset, such as an equity index, ETF or stock. On the downside, Enhanced Barrier Digital Plus Securities generally offer contingent protection, meaning they will return full principal, as well as a Digital Return, as long as the underlying does not close below a specified Final Barrier Level on the final valuation date of the securities. However, Enhanced Barrier Digital Plus Securities provide exposure to the full downside of the underlying if it closes below the Final Barrier Level on the final valuation date . Enhanced Barrier Digital Plus Securities have a typical maturity of between 1 2 months and 5 years. Who might be interested in Enhanced Barrier Digital Plus Securities ? • Current or prospective holders of the underlying • Investors with a moderately bullish view of the underlying looking to potentially outperform a benchmark • Investors looking for a positive return on their investment if the return of the underlying is positive but limited, or moderately negative • Investors looking for limited protection from a decline in the underlying • Investors looking to improve their risk adjusted returns by diversifying their portfolio allocations What benefits specific to Enhanced Barrier Digital Plus Securities should you be aware of? Enhanced Barrier Digital Plus Securities offer full repayment of principal and a digital return that provides a minimum return on investment, as long as the underlying does not close below a specified Final Barrier Level on the final valuation date, subject to the credit risk of the issuer and guarantor. Depending on the terms of a specific offering, although subject to uncertainty , gain or loss on a n Enhanced Barrier Digital Plus Security for U.S. federal income tax purposes generally should be long - term capital gain or loss if the Enhanced Barrier Digital Plus Security has been held for more than one year. Investors should review the offering documents regarding the treatment of any specific Enhanced Barrier Digital Plus Securities. What risks specific to Enhanced Barrier Digital Plus Securities should you be aware of? Enhanced Barrier Digital Plus Securities are not capital protected and thus you could receive significantly less than the initial amount you invest . Because the return on Enhanced Barrier Digital Plus Securities may be capped and does not reflect the dividends paid in the underlying, Enhanced Barrier Digital Plus Securities may underperform a direct investment in the underlying. You will not receive any periodic payments of interest or any other periodic payments, such as dividends paid on the underlying, while holding the Enhanced Barrier Digital Plus Securities . For additional risks, please see the “Key R isks A ssociated with Enhanced Barrier Digital Plus Securities ” on the following page. For a full description of the risks involved with this type of investment, please review the “Key Risks Relating to the Securities” in any Enhanced Barrier Digital Plus Security pricing supplement. Direct Underlying Investment “One - for - one” risk and return O verv i ew On the upside, Enhanced Barrier Digital Plus Securities offer the greater of (i) a Digital Return (fixed amount) and (ii) some level of participation in the appreciation of an underlying. This upside performance is often limited by a M aximum R eturn. Return of Investment Return of Underlying Underlying Return Note Return Enhanced Barrier Digital Plus Securities Investment Modified risk and return Return of Investment Return of Underlying

Citigroup Global Markets Holdings Inc. 3 You may lose a significant portion or all of your investment Unlike conventional debt securities, Enhanced Barrier Digital Plus Securities do not repay a fixed amount of principal at maturity. Instead, the payment at maturity will depend on the performance of the underlying. If the underlying depreciates below its Final Barrier Level on the final valuation date, investors will lose 1% of the stated principal amount of the Enhanced Barrier Digital Plus Securities for every 1% by which the underlying has depreciated from its initial value. Enhanced Barrier Digital Plus Securities do not pay interest Unlike conventional debt securities, Enhanced Barrier Digital Plus Securities do not pay interest or any other amounts prior to maturity. The potential return on capped Enhanced Barrier Digital Plus Securities is limited If the Enhanced Barrier Digital Plus Securities are subject to a cap, the potential total return on the Enhanced Barrier Digital Plus Securities at maturity will be limited to the Maximum Return at maturity. Holders of Enhanced Barrier Digital Plus Securities will not receive dividends Holders of Enhanced Barrier Digital Plus Securities will not receive the dividends that would be paid on a direct investment in the underlying . This lost dividend yield may be significant over the term of the Enhanced Barrier Digital Plus Securities and may cause the Enhanced Barrier Digital Plus Securities to underperform a direct investment in the underlying even if the underlying return does not exceed the Maximum Return . The securities are subject to the credit risk of the issuer and guarantor If the issuer or guarantor defaults on their obligations, holders of Enhanced Barrier Digital Plus Securities may not receive anything owed to them under the securities. Enhanced Barrier Digital Plus Securities will not be listed on any securities exchange and holders may not be able to sell them prior to maturity Enhanced Barrier Digital Plus Securities will not be listed on any securities exchange. Therefore, there may be little or no secondary market for the Enhanced Barrier Digital Plus Securities . The value of the Enhanced Barrier Digital Plus Securities prior to maturity will fluctuate based on many unpredictable factors The value of Enhanced Barrier Digital Plus Securities prior to maturity will fluctuate based on the price and volatility of the underlying and a number of other factors, including dividend yield on the underlying, interest rates generally, the time remaining to maturity and the issuer’s creditworthiness . The value of Enhanced Barrier Digital Plus Securities at any time prior to maturity may be significantly less than the issue price. Investors may not receive the benefit of the barrier in any sale prior to maturity. The issuer and its affiliates may have conflicts of interest with investors The issuer and its affiliates may have a number of conflicts of interest with investors in the Enhanced Barrier Digital Plus Securities as a result of their hedging, trading and other business activities. The United States federal tax consequences of an investment in the Enhanced Barrier Digital Plus Securities are uncertain There is no direct legal authority regarding the proper U.S. federal tax treatment of Enhanced Barrier Digital Plus Securities , and we do not plan to request a ruling from the Internal Revenue Service (the “IRS”). Consequently, significant aspects of the tax treatment of these investments are uncertain. Investors should refer to the applicable offering document(s) for each Enhanced Barrier Digital Plus Securities regarding its U.S. federal tax treatment. However, no assurance can be given that the IRS will agree with the treatment described within the offering document(s) for a particular Enhanced Barrier Digital Plus Securities . Citigroup Inc., its affiliates, and employees do not provide tax or legal advice. Investors should consult with their own professional advisor(s) on such matters before investing in any Enhanced Barrier Digital Plus Security . Key Risks Associated with Enhanced Barrier Digital Plus Securities

Citigroup Global Markets Holdings Inc. 4 Digital Return Final Barrier Level Maximum Return Upside Participation Rate An amount, such as 10%, which indicates a contingent minimum return at maturity, as long as the underlying does not close below the Final Barrier Level on the final valuation date A value, such as 70% of the initial value of the underlying, which is the value of the underlying below which investors will realize a loss on their investment. If the underlying closes below the Final Barrier Level on the final valuation date, the investor is exposed to any negative return of the underlying. If the underlying closes at or above the Final Barrier Level on the final valuation date, the investor is protected from any negative return of the underlying and will receive the Digital Return, subject to the credit risk of the issuer and guarantor An amount, such as 30%, which signifies your overall return limit on the securities An amount, such as 10 0%, which signifies the rate at which you would participate in any return of the underlying in excess of the Digital Return, up to the Maximum Return How Do Enhanced Barrier Digital Plus Securities Work? Each Enhanced Barrier Digital Plus Securities will specify the following terms: Payment at maturity depends only on where the underlying is on a final valuation date, shortly before maturity. The amount you receive at maturity for any Enhanced Barrier Digital Plus Security can be determined by answering the following questions: Is the return of the underlying positive at maturity? Is the return of the underlying multiplied by the Upside Participation Rate greater than the Digital Return ? Is the final value of the underlying equal to or above the Final Barrier Level ? Your return will be negative and will equal the return of the underlying You will receive your initial in v e s t m ent ba c k at maturity plus the Digital Return You will receive your initial in v e s t m ent ba c k at maturity plus the Digital Return Is the return of the underlying multiplied by the Upside Participation Rate greater than the Maximum Return ? no y es no y es no y es Your return will equal the return of the underlying multiplied by the Upside Participation Rate Your return will equal the M aximum R etu r n no y es

Citigroup Global Markets Holdings Inc. 5 Enhanced Barrier Digital Plus Securities offer the potential to outperform the underlying if the underlying depreciates moderately or if it appreciates moderately. Enhanced Barrier Digital Plus Securities will underperform the underlying if the underlying appreciates by more than the Maximum Return and may underperform the underlying in other scenarios after forgone dividends are taken into account. The diagram below illustrates what you would receive at maturity for a range of hypothetical underlying returns. The terms of the Enhanced Barrier Digital Plus Securities are hypothetical only and not representative of the performance of any particular security. The specific terms and conditions will vary for each offering of Enhanced Barrier Digital Plus Securities and should be considered carefully before investing. The shaded areas of outperformance and underperformance below do not take into account forgone dividends on the underlying, which may be significant. How Do Enhanced Barrier Digital Plus Securities Compare to a Direct Investment in the Underlying? The left half of the diagram above illustrates the scenarios where the underlying has finished below its initial value . A direct investment in the underlying would result in a loss . An investment in the Enhanced Barrier Digital Plus Security may also result in a loss, but only insofar as the underlying ends at or below the Final Barrier Level on the final valuation date . Otherwise, the Enhanced Barrier Digital Plus Security pays back the full principal plus the Digital Return , and thus the Enhanced Barrier Digital Plus Security outperforms (subject to forgone dividend yield) in these scenarios . The right half of the diagram above illustrates the scenarios where the underlying has finished above its initial value . As you can see, if the underlying has appreciated modestly, the Enhanced Barrier Digital Plus Security may provide outperformance because of the Digital Return (subject to forgone dividend yield) . However, if the underlying appreciates beyond the M aximum R eturn of the security, the Enhanced Barrier Digital Plus Security will not participate and thus underperform. In summary, a n Enhanced Barrier Digital Plus Security could be an attractive alternative to a direct investment in an underlying if you believe that underlying has moderate growth potential but also some potential for moderate negative returns. A n Enhanced Barrier Digital Plus Security is likely not an attractive investment if you believe the underlying will appreciate significantly, because the upside is limited in this investment, or if you seek dividends. Additionally, a n Enhanced Barrier Digital Plus Security is not appropriate for an outright bearish view, because although the Enhanced Barrier Digital Plus Security does provide some protection against losses, and the potential for a positive return on investment in moderately bearish scenarios, it is ultimately exposed to the downside in the underlying and you may lose money as a result. The protection against losses provided by Enhanced Barrier Digital Plus Securities is subject to the credit risk of the issuer and guarantor. Source: Citi -60% -40% -20% 0% 20% 40% 60% 50% 45% 40% 35% 30% 25% 20% 15% 10% 5% 0% -5% -10% -15% -20% -25% -30% -35% -40% -45% -50% Enhanced Barrier Digital Plus Underlying Return Note Return

Citigroup Global Markets Holdings Inc. 6 Although Enhanced Barrier Digital Plus Securities can be linked to many different assets, Enhanced Barrier Digital Plus Securities are often used as equity replacement strategies, because their payout reflects a modification of the traditional equity investme nt. Due to the potential for a n Enhanced Barrier Digital Plus Security to add protection and reduce the market risk of a portfolio, one strategy that may be appealing is to replace some of your equity allocation for equivalent product linked to that same equity universe. For example, if you were planning to invest 30% of your portfolio in large cap US equities, perhaps an attractive strategy could be to invest 25% directly in the large cap equities of your choosing and 5% in Enhanced Barrier Digital Plus Securities tied to the S&P 500® Index. This way, you maintain your US large cap allocation, but have added the benefits of a n Enhanced Barrier Digital Plus Security . Additionally, rather than investing that 5% portion in a single investment, it may be beneficial to “ladder” the investments so that your returns are not tied to a single point in time, but are rather spread out across different environments. This strategy can be utilized in many different allocation models. Because Enhanced Barrier Digital Plus Securities are unsecured debt securities of the issuer, you should also consider diversification of issuer credit risk in any allocation to Enhanced Barrier Digital Plus Securities . How Do Enhanced Barrier Digital Plus Securities Fit in a Portfolio? Source: Citi In the hypothetical portfolio above, the investor has replaced 10% of his portfolio with various Enhanced Barrier Digital Plus Securities , but has maintained his overall strategic allocation mix. This portfolio will likely limit some of the potential gains within the equity portfolio and add issuer credit risk, in exchange for an increase in the overall protection and potential decrease in overall market risk, both of which have the potential to lead to better risk adjusted returns. This portfolio is not meant to suggest an actual allocation, and indeed, your mix of different asset classes should reflect your personal needs and risk tolerance, which can look very different from this example. The above is meant to help illustrate how Enhanced Barrier Digital Plus Securities can be included within one’s portfolio, while not changing any strategic allocation. US Large Cap E qu i t i es ; 30.00% Non - US Large Cap Equities; 15.00% US Small/Mid Cap Equities ; 4.00% N on - US S m a ll / M id Equities; 2.00% E m erg i n g M ar k et Equities; 8.00% Fixed Income; 39.00% Cash; 2.00% 25% US Large Cap Equities 13% Non - US Large Cap Equities 3% Small/Mid Cap Equities 6% Emerging Market Equities Hypothetical Investor Portfolio G lo b a l E q u iti es F i x e d I n co m e C a sh 5% S&P 500 ® Index Linked Enhanced Barrier Digital Plus Securities 2% EUROSTOXX 50® Index Linked Enhanced Barrier Digital Plus Securities 1% Russell 2000 ® Index Linked Enhanced Barrier Digital Plus Securities 2% iShares® MSCI Emerging Markets ETF Linked Enhanced Barrier Digital Plus Securities

Citigroup Global Markets Holdings Inc. 7 Variations This guide describes the most common version of the Enhanced Barrier Digital Plus Securities , but there are a few variations you may see in the market. The Enhanced Barrier Digital Plus Securities in this guide are all discussing a single underlying , but they can be linked to one or more underlyings within the same investment. This can either be in basket form, where the return is some average of the returns of the underlyings, or as a worst of option, where the return is linked to the worst performing underlying among a number of underlyings. Generally , this worst performing variation is for investors willing to take on some additional risk in order to increase the return potential. Rather than capping the upside, Enhanced Barrier Digital Plus Securities can be uncapped , meaning there is no limit on the return of the security. Conversely, for investors who expect only very modest upside in the underlying, the upside participation can be removed completely in exchange for a larger Digital Return. Finally, more bullish or risk - tolerant investors may prefer a Digital Return that is paid out only if the underlying ends above its initial value, as opposed to above the Final Barrier Level, on the final valuation date, in exchange for a higher digital amount. S a l e s I n f or m a ti on Enhanced Barrier Digital Plus Securities are available through periodic investment offerings as well as through the customized solutions platform . For current offerings of Enhanced Barrier Digital Plus Securities , as well as other structured investment offerings, please contact your Investment Professional or Financial Advisor. Other Information Any figures or terms provided in this product brochure are sample product terms, illustrative and are no indication of what final terms or actual returns will be. This product summary supplement does not consider the effect taxes and fees will have on your returns. The terms of each security vary from offering to offering. For terms relating to particular offerings, including direct and indirect risks and other material considerations, you should refer to that product’s offering documents. Citigroup Global Markets Inc. and its affiliates (“Citi”) do not guarantee that a secondary market will develop in any Enhanced Barrier Digital Plus Security . If a second ary market does develop it may not be liquid and may not continue for the term of the security. If the secondary market is limited there may be few buyers should you choose to sell the security prior to maturity and this may reduce the price you receive. There is no guarantee that investors wishing to liquidate an investment in such securities prior to the stated maturity will receive a price equal to or in excess of the initial principal amount invested. The value of Enhanced Barrier Digital Plus Securities may rise as well as fall during the term of the security and the return on any product may be lower than what could be earned on a conventional investment of similar duration and credit risk. For each product, investors assume the full credit risk of the issuer and guarantor of issuer’s obligations. The deterioration of the credit of any of these entities may result in the loss of your principal invested. Products may provide for adjustments to be made to their final terms during their term due to certain events including corporate actions, mergers and acquisitions, divestitures, price source disruption, trading suspension and material change in index formula and/or index content. Citi may at any time hold long or short positions. Accordingly, Citi may actively trade these and related securities for its own account and those of its customers and, at any time, may have long or short positions in and buy and sell, the securities, commodities, futures, options, derivatives or other instruments and investments identical with or related to those mentioned in this product summary supplement. Before making an investment in a specific Enhanced Barrier Digital Plus Security you should obtain and carefully read the offering documents relating to that offering, which will contain additional information needed to evaluate the investment and provide important disclosures regarding risks, fees and expenses. Additionally, such offering documents will contain the only complete description, and final terms, of the terms and conditions of that offering. Before making any commitment to invest, you should take whatever business, legal, tax, accounting or other advice you consider necessary given your particular circumstances. If you invest in a n Enhanced Barrier Digital Plus Security , you are responsible for any tax lawfully due from you on the income or gains arising from such investment. Citi does not provide business, legal, tax or accounting advice and makes no representation in respect of any of them. Enhanced Barrier Digital Plus Securities are not deposits and are neither obligations of nor guaranteed by Citibank, or any governmental entity or agency. If you have any doubt about the suitability of these investments, you should contact your own advisers for advice. Additional Information

©202 6 Citigroup Global Markets Inc. All rights reserved. Citi and Citi and Arc Design are trademarks and service marks of Citigroup Inc. or its subsidiaries and are used and registered throughout the world. Lea r n M o r e Please contact your Investment Professional if you are looking to potentially buy Enhanced Barrier Digital Plus Securities . Financial Advisors and Distribution partners may contact our sales professionals at: +1 (212) 723 - 3916 (Citi private banking channel) +1 (212) 723 - 7288 (Citi consumer banking channels) +1 (212) 723 - 3136 (external channels) At Citi, our talented professionals are dedicated to delivering innovative value added investments and services to our clients across the globe.

FAQ

What are Enhanced Barrier Digital Plus Securities from Citigroup (C)?

They are unsecured debt securities of Citigroup Global Markets Holdings Inc., guaranteed by Citigroup Inc., with payoffs tied to an underlying asset. They do not pay periodic interest or dividends and maturity payment depends on barrier and payoff terms in the pricing supplement.

How does the Final Barrier Level affect payoff for C Enhanced Barrier notes?

If the underlying closes at or above the Final Barrier Level on the final valuation date, holders receive principal plus the Digital Return. If it closes below that level, holders are exposed to the full negative return of the underlying.

What limits upside returns on these Citigroup products?

Upside may be limited by a stated Maximum Return and an Upside Participation Rate; if the underlying’s appreciation exceeds the Maximum Return, the note’s payoff is capped at that Maximum Return, per the offering terms.

Are Enhanced Barrier Digital Plus Securities insured or bank deposits?

No. They are unsecured obligations of the issuer and guarantor, not bank deposits, and are not insured by the FDIC or any government agency. Investors assume the issuer and guarantor credit risk.

Will holders receive dividends from the underlying while holding the security?

No. Holders do not receive periodic dividends paid on the underlying; forgone dividends may cause underperformance relative to a direct investment in the underlying, as noted in the product materials.