Autocallable Securities Linked to the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER Due November 26, 2030

(Key Terms continued on next page) 

(1) Citigroup Global Markets Holdings Inc. currently expects that the estimated value of the securities on the pricing date will be at least $850.00 per security, which will be less than the issue price. The estimated value of the securities is based on CGMI’s proprietary pricing models and our internal funding rate. It is not an indication of actual profit to CGMI or other of our affiliates, nor is it an indication of the price, if any, at which CGMI or any other person may be willing to buy the securities from you at any time after issuance. See “Valuation of the Securities” in this pricing supplement.

(2) CGMI will receive an underwriting fee of up to $45.00 for each security sold in this offering.  The total underwriting fee and proceeds to issuer in the table above give effect to the actual total underwriting fee.  For more information on the distribution of the securities, see “Supplemental Plan of Distribution” in this pricing supplement.  In addition to the underwriting fee, CGMI and its affiliates may profit from expected hedging activity related to this offering, even if the value of the securities declines. See “Use of Proceeds and Hedging” in the accompanying prospectus.

(3) The per security proceeds to issuer indicated above represent the minimum per security proceeds to issuer for any security, assuming the maximum per security underwriting fee. As noted above, the underwriting fee is variable.

Investing in the securities involves risks not associated with an investment in conventional debt securities. See “Summary Risk Factors” beginning on page PS-9.

Neither the Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapproved of the securities or determined that this pricing supplement and the accompanying product supplement, index supplement, prospectus supplement and prospectus are truthful or complete. Any representation to the contrary is a criminal offense. 

You should read this pricing supplement together with the accompanying product supplement, index supplement, prospectus supplement and prospectus, which can be accessed via the hyperlinks below: 

Prospectus Supplement and Prospectus each dated March 7, 2023 

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.

Additional Information

The terms of the securities are set forth in the accompanying product supplement, prospectus supplement and prospectus, as supplemented by this pricing supplement. The accompanying product supplement, prospectus supplement and prospectus contain important disclosures that are not repeated in this pricing supplement. For example, the accompanying product supplement contains important information about how the closing value of the underlying will be determined and about adjustments that may be made to the terms of the securities upon the occurrence of market disruption events and other specified events with respect to the underlying. The accompanying index supplement contains important information about the underlying that is not repeated in this pricing supplement. It is important that you read the accompanying product supplement, index supplement, prospectus supplement and prospectus together with this pricing supplement in deciding whether to invest in the securities. Certain terms used but not defined in this pricing supplement are defined in the accompanying product supplement or the accompanying index supplement.

Summary Index Description

All information contained in this pricing supplement regarding the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER (the “underlying” or the “Index”) has been derived from information provided by S&P Dow Jones Indices LLC, the Index sponsor, without independent verification.  This information reflects the policies of, and is subject to change by, the Index sponsor.  The Index sponsor has no obligation to continue to publish the Index and may discontinue publication of the Index at any time. The Index launched on August 14, 2025 and, therefore, has a limited performance history.

The Index tracks exposure to the S&P 500 Futures Excess Return Index (which we refer to as the “Underlying Futures Index”) on a volatility-targeted, trend-adjusted basis, less certain notional costs and less a decrement of 6% per annum.  The Index has a volatility target of 40%, which it attempts to achieve by applying leverage to its exposure to the Underlying Futures Index (up to a maximum of 500%) when the underlying volatility is less than the volatility target, and by reducing its exposure to the Underlying Futures Index below 100% when the underlying volatility is greater than the volatility target.  The Index may reset its exposure to the Underlying Futures Index at each of four intraday windows during each index business day based on a measure of the underlying volatility at the related intraday fixing time, subject to scaling up or down depending on a measure of the intraday trend of the Underlying Futures Index at that time (and, for the fourth intraday window only, subject to adjustment up or down based on the overnight mean-reversion trend), and may reset its exposure again at the closing of trading, all as described in more detail in the accompanying Index Supplement.

The Underlying Futures Index tracks the performance of a hypothetical investment, rolled quarterly, in futures contracts on the S&P 500^® Index, and accordingly is expected to reflect the performance of the S&P 500^® Index less an implicit financing cost.  The S&P 500^® Index consists of the common stocks of 500 issuers selected to provide a performance benchmark for the large capitalization segment of the U.S. equity market.  

The methodology of the Index is premised on the following key assumptions: (1) that there will be an inverse relationship between performance and volatility, so that the Underlying Futures Index will tend to increase in times of lower volatility and decline in times of higher volatility; (2) that short-term intraday trends in the value of the Underlying Futures Index will tend to continue; (3) that the Index rules can effectively identify when conditions are favorable for an overnight mean-reversion in the Underlying Futures Index and effectively adjust its exposure to the Underlying Futures Index up or down in response; (4) that the applicable measures of underlying volatility used by the Index will be effective predictors of future volatility of the Underlying Futures Index from one intraday window to the next; and (5) that the volatility target for the Index will be an effective level of volatility at which to draw the line between leveraged exposure and deleveraged exposure to the Underlying Futures Index.  If these assumptions prove to be consistently correct, then the Index has the potential to outperform the Underlying Futures Index by participating in increases on a leveraged basis and declines on a deleveraged basis.  There is no guarantee, however, that these assumptions will be proven correct over any given time period.  If any of these assumptions does not prove to be consistently correct, then the Index may perform poorly as a result of having highly leveraged exposure to the Underlying Futures Index at a time of declines and/or having reduced exposure to the Underlying Futures Index at a time of increases.

If the Index is not consistently successful in increasing exposure to the Underlying Futures Index in advance of increases in the Underlying Futures Index and reducing exposure to the Underlying Futures Index in advance of declines, then the Index is also expected to be subject to a “decay” effect, which will exacerbate the decline in the Index that results from having highly leveraged exposure to declines in the Underlying Futures Index.  The decay effect would result from the fact that the Index resets its exposure to the Underlying Futures Index multiple times each index business day, and would manifest any time the Underlying Futures Index moves in one direction from one intraday window to the next and another direction from that subsequent intraday window to the next after that.  The decay effect would result because resetting exposure after an increase but in advance of a decline would cause the Index to have increased exposure to that decline, and resetting exposure following a decline but in advance of an increase would cause the Index to have decreased exposure to that increase.  The more this fact pattern repeats, the lower the performance of the Index would be relative to the performance of the Underlying Futures Index.

It is important to understand that the Index provides exposure to the S&P 500^® Index that:

As a result of these features, the Index may significantly underperform the S&P 500^® Index.  The Index is likely to significantly underperform the S&P 500^® Index if it is not consistently successful in increasing exposure to the Underlying Futures Index in advance of increases in the Underlying Futures Index and reducing exposure to the Underlying Futures Index in advance of declines in the Underlying Futures Index.  The Index may significantly underperform the S&P 500^® Index even if it is consistently successful in these respects because of the implicit financing cost, the notional costs and the decrement, or because the reduced exposure of the Index to the Underlying Futures Index at a time of a decline may nevertheless reflect significantly greater than 100% participation in the decline of the Underlying Futures Index.

Certain features of the Index – including the fact that it references the Underlying Futures Index, and not the S&P 500^® Index directly, the deduction of notional costs and the decrement of 6% per annum – are designed to reduce and/or offset the cost to us and our affiliates of hedging transactions that we intend to enter into in connection with the securities as compared to an otherwise comparable index without these features.  These features will reduce the performance of the Index as compared to an otherwise comparable index without these features.  The reduced and/or offset cost of hedging may make it possible for certain terms of the securities to be more favorable to you than would otherwise be the case.  However, there can be no assurance that these more favorable terms will offset the negative effects of these features on the performance of

the Index, and your return on the securities may ultimately be less favorable than it would have been without these more favorable terms but with an index that does not contain these features.

This section contains only a summary description of the Index and does not describe all of its important features in detail.  Before investing in the securities, you should carefully review the more detailed description of the Index in the accompanying Index Supplement.

Hypothetical Payment Upon Automatic Early Redemption

The following table illustrates how the amount payable per security upon automatic early redemption will be calculated if the closing value of the underlying on any valuation date prior to the final valuation date is greater than or equal to the initial underlying value.

If, on any valuation date prior to the final valuation date, the closing value of the underlying is less than the initial underlying value, you will not receive the premium indicated above following that valuation date. In order to receive the premium indicated above, the closing value of the underlying on the applicable valuation date must be greater than or equal to the initial underlying value.

Payment at Maturity Diagram

The diagram below illustrates your payment at maturity of the securities, assuming the securities have not previously been automatically redeemed, for a range of hypothetical underlying returns.

Investors in the securities will not receive any dividends with respect to the underlying. The diagram and examples below do not show any effect of lost dividend yield over the term of the securities. See “Summary Risk Factors—You will not receive dividends or have any other rights with respect to the underlying” below.

Payment at Maturity Diagram
n The Securities	n The Underlying

Hypothetical Examples of the Payment at Maturity

The examples below are intended to illustrate how, if the securities are not automatically redeemed prior to maturity, your payment at maturity will depend on the final underlying value. Your actual payment at maturity per security, if the securities are not automatically redeemed prior to maturity, will depend on the actual final underlying value. The examples are solely for illustrative purposes, do not show all possible outcomes and are not a prediction of any payment that may be made on the securities.

The examples below are based on the following hypothetical values and do not reflect the actual initial underlying value or final barrier value. For the actual initial underlying value and final barrier value, see the cover page of this pricing supplement. We have used these hypothetical values, rather than the actual values, to simplify the calculations and aid understanding of how the securities work. However, you should understand that the actual payment at maturity on the securities will be calculated based on the actual initial underlying value and final barrier value, and not the hypothetical values indicated below. For ease of analysis, figures below have been rounded.

Example 1—Upside Scenario. The final underlying value is 110.00, resulting in a 10.00% underlying return. In this example, the final underlying value is greater than the initial underlying value.

Payment at maturity per security = $1,000 + the premium applicable to the final valuation date

= $1,000 + $1,100.00

= $2,100.00

In this scenario, because the final underlying value is greater than the initial underlying value, you would be repaid the stated principal amount of your securities at maturity plus the premium applicable to the final valuation date.

Example 2—Par Scenario. The final underlying value is 85.00, resulting in a -15.00% underlying return. In this example, the final underlying value is less than the initial underlying value but greater than the final barrier value.

Payment at maturity per security = $1,000.00

In this scenario, the underlying has depreciated from the initial underlying value to the final underlying value so that the final underlying value is less than the initial underlying value but not below the final barrier value. As a result, you would be repaid the stated principal amount of your securities at maturity but would not receive any positive return on your investment.

Example 3—Downside Scenario. The final underlying value is 30.00, resulting in a -70.00% underlying return. In this example, the final underlying value is less than the final barrier value.

Payment at maturity per security = $1,000 + ($1,000 × the underlying return)

= $1,000 + ($1,000 × -70.00%)

= $1,000 + -$700.00

= $300.00

In this scenario, the underlying has depreciated from the initial underlying value to the final underlying value and the final underlying value is less than the final barrier value. As a result, your total return at maturity in this scenario would be negative and would reflect 1-to-1 exposure to the negative performance of the underlying.

Summary Risk Factors

An investment in the securities is significantly riskier than an investment in conventional debt securities. The securities are subject to all of the risks associated with an investment in our conventional debt securities (guaranteed by Citigroup Inc.), including the risk that we and Citigroup Inc. may default on our obligations under the securities, and are also subject to risks associated with the underlying. Accordingly, the securities are suitable only for investors who are capable of understanding the complexities and risks of the securities. You should consult your own financial, tax and legal advisors as to the risks of an investment in the securities and the suitability of the securities in light of your particular circumstances.

The following is a summary of certain key risk factors for investors in the securities. You should read this summary together with the more detailed description of risks relating to an investment in the securities contained in the section “Risk Factors Relating to the Securities” beginning on page EA-7 in the accompanying product supplement. You should also carefully read the risk factors included in the accompanying prospectus supplement and in the documents incorporated by reference in the accompanying prospectus, including Citigroup Inc.’s most recent Annual Report on Form 10-K and any subsequent Quarterly Reports on Form 10-Q, which describe risks relating to the business of Citigroup Inc. more generally.

Risks relating to the securities

offering of the securities, (ii) hedging and other costs incurred by us and our affiliates in connection with the offering of the securities and (iii) the expected profit (which may be more or less than actual profit) to CGMI or other of our affiliates in connection with hedging our obligations under the securities. These costs adversely affect the economic terms of the securities because, if they were lower, the economic terms of the securities would be more favorable to you. The economic terms of the securities are also likely to be adversely affected by the use of our internal funding rate, rather than our secondary market rate, to price the securities. See “The estimated value of the securities would be lower if it were calculated based on our secondary market rate” below.

Because there is not an active market for traded instruments referencing our outstanding debt obligations, CGMI determines our secondary market rate based on the market price of traded instruments referencing the debt obligations of Citigroup Inc., our parent company and the guarantor of all payments due on the securities, but subject to adjustments that CGMI makes in its sole discretion. As a result, our secondary market rate is not a market-determined measure of our creditworthiness, but rather reflects the market’s perception of our parent company’s creditworthiness as adjusted for discretionary factors such as CGMI’s preferences with respect to purchasing the securities prior to maturity.

If you are a non-U.S. investor, you should review the discussion of withholding tax issues in “United States Federal Tax Considerations—Non-U.S. Holders” below.

You should read carefully the discussion under “United States Federal Tax Considerations” and “Risk Factors Relating to the Securities” in the accompanying product supplement and “United States Federal Tax Considerations” in this pricing supplement.  You should also consult your tax adviser regarding the U.S. federal tax consequences of an investment in the securities, as well as tax consequences arising under the laws of any state, local or non-U.S. taxing jurisdiction.

Risks relating to the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER

The following is a description of risks relating to the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER, which we refer to in this section as the “Index”. The following discussion of risks should be read together with the section “Description of the S&P 500 Futures Intraday Edge Volatility Indices” in the accompanying index supplement, which defines and further describes a number of the terms and concepts referred to below.

when the Index has leveraged exposure to it, the decline in the Index will be equal to the decline in the Underlying Futures Index multiplied by the leveraged exposure (subject to further reduction as a result of the notional costs and the decrement). For example, if the Underlying Futures Index declines by 5% at a time when the Index has 500% leveraged exposure to the Underlying Futures Index, the Index will decline by 25% over that time (subject to further reduction as a result of the notional costs and the decrement).  This potential for losses on a highly leveraged basis makes the Index highly risky.

Moreover, even if the Underlying Futures Index does exhibit trend-following behavior, there can be no assurance that the particular methodology followed by the Index will effectively identify the trend or capitalize on it.  If the Underlying Futures Index does not exhibit momentum, or if the Index’s intraday trend-following methodology is not effective in identifying trends and capitalizing on them, the Index’s trend-following mechanism may result in scaling up the exposure to the Underlying Futures Index ahead of declines, and scaling down exposure ahead of increases, which would result in poor performance.

result of the notional costs and the decrement, the level of the Index may decline even if the return of the Index methodology would otherwise have been positive.

performance of the Index prior to May 11, 2022 may therefore differ from how the Index would have performed if SPXW options had been available with expirations on every weekday, as they are now.

It is impossible to predict whether the Index will rise or fall. The actual future performance of the Index may bear no relation to the historical or hypothetical back-tested levels of the Index.

Additional Terms of the Securities

Market disruption events. For purposes of determining whether a market disruption event occurs with respect to the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER, each reference to the “Underlying Index” in the section “Description of the Securities—Certain Additional Terms for Securities Linked to an Underlying Index—Definitions of Market Disruption Event and Scheduled Trading Day and Related Definitions” in the accompanying product supplement in the definition of Market Disruption Event (and defined terms used in the definition of Market Disruption Event) shall be deemed replaced with a reference to the “Underlying Index, the S&P 500 Futures Excess Return Index or the S&P 500^® Index”.  References in the section “Description of the Securities—Certain Additional Terms for Securities Linked to an Underlying Index—Definitions of Market Disruption Event and Scheduled Trading Day and Related Definitions” in the accompanying product supplement to the securities comprising an Underlying Index (or any other index) shall be deemed to include futures contracts comprising an Underlying Index (or any other index), and each reference to “at any time during the one-hour period that ends at the Closing Time” shall be deemed to be replaced by a reference to “at any time during the trading day”.

Material modification of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER. If the sponsor of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER announces that it will make, or that it will undertake a consultation with respect to, a material change in the formula for or the method of calculating the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER or any other material modification of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER (other than a modification prescribed in that formula or method to maintain the index in the event of changes in constituent stock and capitalization and other routine events) (any such announcement, a “material modification event”), then the issuer may, at its option, direct the calculation agent to calculate the closing level of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER on each date of determination after the effective date of such change in accordance with the formula for and method of calculating the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER last in effect prior to the change. Such level, as calculated by the calculation agent, will be the closing value of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER for all purposes. The terms set forth in this paragraph supersede the terms set forth in the accompanying product supplement with respect to the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER to the extent they are inconsistent with such terms. For purposes of determining whether there has been a material modification to the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER, a material modification to the S&P 500 Futures Excess Return Index or the S&P 500^® Index shall be treated as though it were a material modification to the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER. Furthermore, any modification to the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER will be treated as a material modification unless made under the following circumstances: (i) to exercise routine judgment in the administration of the rules, provided that such routine judgment will not include deviations or alterations to the rules designed to improve the financial performance of the index; (ii) to correct errors in implementation of the rules or calculations made pursuant to the rules; or (iii) to make an adjustment to respond to an unanticipated event outside of the control of the sponsor of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER, such as a stock split, merger, listing or delisting, nationalization, or insolvency of a component of the index, a disruption in the financial markets for specific assets or in a particular jurisdiction, regulatory compliance requirement, force majeure or any other unanticipated event of similar magnitude and significance.

If, on any day during the term of the securities, the calculation agent determines that a material modification event has occurred, we will have the right, but not the obligation, to redeem the securities, in whole and not in part, by providing written notice of our election to exercise that right to the trustee (the date of such notice, the “early redemption notice date”) on a redemption date of our election that is no later than the 30th business day immediately following the early redemption notice date or earlier than the fifth business day following the early redemption notice date. A material modification event need not be continuing on the early redemption notice date or on the redemption date. The amount due and payable on the securities upon such redemption will be equal to the early redemption amount determined as of the early redemption notice date.

The “early redemption amount” will be the fair value of the securities determined by the calculation agent as of the early redemption notice date in good faith and in a manner based upon (but not necessarily identical to) CGMI’s then contemporaneous practices for determining a secondary market bid price for the securities and similar instruments. In determining the early redemption amount, the calculation agent may take into account proprietary pricing models and may make adjustments to those models or inputs to those models in good faith and in a commercially reasonable manner. The calculation agent may also take into account other facts, whether or not unique to us or our affiliates, in determining the early redemption amount so long as it is in good faith and commercially reasonable. The early redemption amount may result in a significant loss on your securities. See “Summary Risk Factors—If a material modification event occurs during the term of the securities, we may redeem the securities early for an amount that may result in a significant loss on your investment” in this pricing supplement.

Hypothetical Back-Tested and Historical Performance Information

This section contains hypothetical back-tested performance information for the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER calculated by S&P Dow Jones Indices LLC.  All S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER performance information prior to August 14, 2025 is hypothetical and back-tested, as the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER did not exist prior to that date.  Hypothetical back-tested performance information is subject to significant limitations.  The sponsor of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER developed the rules of the index with the benefit of hindsight—that is, with the benefit of being able to evaluate how the rules would have caused the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER to perform had it existed during the hypothetical back-tested period.  The fact that the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER appreciated at any time during the hypothetical back-tested period may not therefore be an accurate or reliable indication of any fundamental aspect of the index methodology.  Furthermore, the hypothetical back-tested performance of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER might look different if it covered a different historical period.  The market conditions that existed during the hypothetical back-tested period may not be representative of market conditions that will exist in the future.

In addition, the SPXW options used by the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER to determine the implied volatility of the S&P 500^® Index have traded with expirations on every weekday only since May 11, 2022.  When SPXW options were first launched in 2005, only Friday expirations were available.  Wednesday expirations were added on February 23, 2016; Monday expirations were added on August 15, 2016; Tuesday expirations were added on April 18, 2022; and Thursday expirations were added on May 11, 2022.  For purposes of calculating the hypothetical back-tested performance of the Index, the implied volatility for the one-week period ending on a weekday for which no SPXW option was then traded was calculated by interpolating between the SPXW options expiring immediately before and immediately after that weekday.  For these reasons, the hypothetical back-tested performance of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER prior to May 11, 2022 may differ from how the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER would have performed if SPXW options had been available with expirations on every weekday, as they are now.

It is impossible to predict whether the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER will rise or fall.  By providing the hypothetical back-tested and historical performance information below, we are not representing that the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER is likely to achieve gains or losses similar to those shown.  In fact, there are frequently sharp differences between hypothetical performance results and the actual results subsequently achieved by any particular investment.  One of the limitations of hypothetical performance information is that it did not involve financial risk and cannot account for all factors that would affect actual performance.  The actual future performance of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER may bear no relation to its hypothetical back-tested or historical performance.

Historical Information

The closing value of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER on October 28, 2025 was 10,644.39. The graph below shows the hypothetical back-tested closing values of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER for the period from January 2, 2015 to August 13, 2025, and historical closing values of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER for the period from August 14, 2025 to October 28, 2025.  All data to the left of the vertical red line in the graph below are hypothetical and back-tested.  We obtained the closing values from Bloomberg L.P., without independent verification.  You should not take the hypothetical back-tested and historical values of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER as an indication of future performance.

S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER – Hypothetical Back-Tested and Historical Closing Values January 2, 2015 to October 28, 2025

Comparison of Hypothetical Back-Tested and Historical S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER Performance Against Historical S&P 500^® Index Performance

The following graphs set forth a comparison of the hypothetical back-tested and historical performance of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER against the historical performance of the S&P 500^® Index.  The first graph shows comparative performance data for the period from January 2, 2015 through October 28, 2025, each normalized to have a closing value of 100.00 on January 2, 2015 to facilitate a comparison.  The second graph shows comparative performance data for the period from January 3, 2022 through October 28, 2025, each normalized to have a closing value of 100.00 on January 3, 2022 to facilitate a comparison.  The performance of the S&P 500^® Index shown below is its price return performance – i.e., its performance without reflecting dividends. The total return performance of the S&P 500^® Index (i.e., its performance reflecting dividends) would be greater than the price return performance shown below.

All S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER performance information prior to August 14, 2025 is hypothetical and back-tested, as the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER did not exist prior to that date.  Hypothetical back-tested performance information is subject to the significant limitations described above under “Information About the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER”.

In the graphs below, references to “SPXI4EV6” are to the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER and references to “SPX” are to the S&P 500^® Index.

January 2, 2015 to October 28, 2025

January 3, 2022 to October 28, 2025

PAST PERFORMANCE OF THE S&P 500 FUTURES 40% INTRADAY EDGE VOLATILITY TCA 6% DECREMENT INDEX (USD) ER AND RELATIVE PERFORMANCE BETWEEN THE S&P 500 FUTURES 40% INTRADAY EDGE VOLATILITY TCA 6% DECREMENT INDEX (USD) ER AND THE S&P 500^® INDEX ARE NOT INDICATIVE OF FUTURE PERFORMANCE

Using the hypothetical back-tested and historical performance information from the graphs above, the table below shows the annualized (annually compounded) performance of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER as compared to the S&P 500^® Index for the last year, the last three years and the last five years, each as of October 28, 2025.

The table below indicates the negative impact of the notional costs on the performance of the S&P 500 Futures 40% Intraday Edge Volatility TCA 6% Decrement Index (USD) ER based on the hypothetical back-tested and historical information from the graphs above.  In the future, the negative impact of these notional costs may be greater, and perhaps significantly greater, than the values set forth below.

Comparison of Historical S&P 500 Futures Excess Return Index Performance Against Historical S&P 500^® Index Performance

To illustrate the historical impact of the implicit financing cost on the performance of the S&P 500 Futures Excess Return Index, the following graph sets forth a comparison of the historical performance of the S&P 500 Futures Excess Return Index against the historical performance of the S&P 500^® Index from January 2, 2015 through October 28, 2025, each normalized to have a closing value of 100.00 on January 2, 2015 to facilitate a comparison.  The performance of the S&P 500^® Index shown below is its price return performance – i.e., its performance without reflecting dividends.  The total return performance of the S&P 500^® Index (i.e., its performance reflecting dividends) would be greater than the price return performance shown below.

In the graph below, references to “SPXFP” are to the S&P 500 Futures Excess Return Index and references to “SPX” are to the S&P 500^® Index.

January 2, 2015 to October 28, 2025

PAST PERFORMANCE OF THE S&P 500 FUTURES EXCESS RETURN INDEX AND RELATIVE PERFORMANCE BETWEEN THE S&P 500

FUTURES EXCESS RETURN INDEX AND THE S&P 500^® INDEX ARE NOT INDICATIVE OF FUTURE PERFORMANCE

Using the historical performance information from the graph above, the table below shows the annualized (annually compounded) performance of the S&P 500 Futures Excess Return Index as compared to the S&P 500^® Index for the last year, the last three years and the last five years, each as of October 28, 2025.

United States Federal Tax Considerations

You should read carefully the discussion under “United States Federal Tax Considerations” and “Risk Factors Relating to the Securities” in the accompanying product supplement and “Summary Risk Factors” in this pricing supplement.  

In the opinion of our counsel, Davis Polk & Wardwell LLP, a security should be treated as a prepaid forward contract for U.S. federal income tax purposes.  By purchasing a security, you agree (in the absence of an administrative determination or judicial ruling to the contrary) to this treatment. There is uncertainty regarding this treatment, and the IRS or a court might not agree with it.  Moreover, our counsel’s opinion is based on market conditions as of the date of this preliminary pricing supplement and is subject to confirmation on the pricing date.

Assuming this treatment of the securities is respected and subject to the discussion in “United States Federal Tax Considerations” in the accompanying product supplement, the following U.S. federal income tax consequences should result under current law:

We do not plan to request a ruling from the IRS regarding the treatment of the securities. An alternative characterization of the securities could materially and adversely affect the tax consequences of ownership and disposition of the securities, including the timing and character of income recognized. In addition, the U.S. Treasury Department and the IRS have requested comments on various issues regarding the U.S. federal income tax treatment of “prepaid forward contracts” and similar financial instruments and have indicated that such transactions may be the subject of future regulations or other guidance. Furthermore, members of Congress have proposed legislative changes to the tax treatment of derivative contracts. Any legislation, 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. You should consult your tax adviser regarding possible alternative tax treatments of the securities and potential changes in applicable law.

Non-U.S. Holders. Subject to the discussions below and in “United States Federal Tax Considerations” in the accompanying product supplement, if you are a Non-U.S. Holder (as defined in the accompanying product supplement) of the securities, you generally should not be subject to U.S. federal withholding or income tax in respect of any amount paid to you with respect to the securities, provided that (i) income in respect of the securities is not effectively connected with your conduct of a trade or business in the United States, and (ii) you comply with the applicable certification requirements.

As discussed under “United States Federal Tax Considerations—Tax Consequences to Non-U.S. Holders” in the accompanying product supplement, Section 871(m) of the Code and Treasury regulations promulgated thereunder (“Section 871(m)”) generally impose a 30% 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 (“U.S. Underlying Equities”) or indices that include U.S. Underlying Equities.  Section 871(m) generally applies to instruments that substantially replicate the economic performance of one or more U.S. Underlying Equities, as determined based on tests set forth in the applicable Treasury regulations.  However, the regulations, as modified by an IRS notice, exempt financial instruments issued prior to January 1, 2027 that do not have a “delta” of one.  Based on the terms of the securities and representations provided by us as of the date of this preliminary pricing supplement, our counsel is of the opinion that the securities should not be treated as transactions that have a “delta” of one within the meaning of the regulations with respect to any U.S. Underlying Equity and, therefore, should not be subject to withholding tax under Section 871(m).  However, the final determination regarding the treatment of the securities under Section 871(m) will be made as of the pricing date for the securities, and it is possible that the securities will be subject to withholding tax under Section 871(m) based on the circumstances as of that date.

A determination that the securities are not subject to Section 871(m) is not binding on the IRS, and the IRS may disagree with this treatment.  Moreover, Section 871(m) is complex and its application may depend on your particular circumstances, including your other transactions.  You should consult your tax adviser regarding the potential application of Section 871(m) to the securities.

If withholding tax applies to the securities, we will not be required to pay any additional amounts with respect to amounts withheld.

You should read the section entitled “United States Federal Tax Considerations” in the accompanying product supplement.  The preceding discussion, when read in combination with that section, constitutes the full opinion of Davis Polk & Wardwell LLP regarding the material U.S. federal tax consequences of owning and disposing of the securities.  

You should also consult your tax adviser regarding all aspects of the U.S. federal income and estate tax consequences of an investment in the securities and any tax consequences arising under the laws of any state, local or non-U.S. taxing jurisdiction.

Supplemental Plan of Distribution

CGMI, an affiliate of Citigroup Global Markets Holdings Inc. and the underwriter of the sale of the securities, is acting as principal and will receive an underwriting fee of up to $45.00 for each security sold in this offering. The actual underwriting fee will be equal to the selling concession provided to selected dealers, as described in this paragraph. From this underwriting fee, CGMI will pay selected dealers not affiliated with CGMI a variable selling concession of up to $45.00 for each security they sell. For the avoidance of doubt, any fees or selling concessions described in this pricing supplement will not be rebated if the securities are automatically redeemed prior to maturity.

See “Plan of Distribution; Conflicts of Interest” in the accompanying product supplement and “Plan of Distribution” in each of the accompanying prospectus supplement and prospectus for additional information.

Valuation of the Securities

CGMI calculated the estimated value of the securities set forth on the cover page of this pricing supplement based on proprietary pricing models. CGMI’s proprietary pricing models generated an estimated value for the securities by estimating the value of a hypothetical package of financial instruments that would replicate the payout on the securities, which consists of a fixed-income bond (the “bond component”) and one or more derivative instruments underlying the economic terms of the securities (the “derivative component”). CGMI calculated the estimated value of the bond component using a discount rate based on our internal funding rate. CGMI calculated the estimated value of the derivative component based on a proprietary derivative-pricing model, which generated a theoretical price for the instruments that constitute the derivative component based on various inputs, including the factors described under “Summary Risk Factors—The value of the securities prior to maturity will fluctuate based on many unpredictable factors” in this pricing supplement, but not including our or Citigroup Inc.’s creditworthiness. These inputs may be market-observable or may be based on assumptions made by CGMI in its discretionary judgment.

The estimated value of the securities is a function of the terms of the securities and the inputs to CGMI’s proprietary pricing models.  As of the date of this preliminary pricing supplement, it is uncertain what the estimated value of the securities will be on the pricing date because it is uncertain what the values of the inputs to CGMI’s proprietary pricing models will be on the pricing date.

For a period of approximately four months following issuance of the securities, the price, if any, at which CGMI would be willing to buy the securities from investors, and the value that will be indicated for the securities on any brokerage account statements prepared by CGMI or its affiliates (which value CGMI may also publish through one or more financial information vendors), will reflect a temporary upward adjustment from the price or value that would otherwise be determined. This temporary upward adjustment represents a portion of the hedging profit expected to be realized by CGMI or its affiliates over the term of the securities. The amount of this temporary upward adjustment will decline to zero on a straight-line basis over the four-month temporary adjustment period. However, CGMI is not obligated to buy the securities from investors at any time.  See “Summary Risk Factors—The securities will not be listed on any securities exchange and you may not be able to sell them prior to maturity.”

Contact

Clients may contact their local brokerage representative. Third-party distributors may contact Citi Structured Investment Sales at (212) 723-7005.

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