Primary Offering Prospectus - Form 424B2

Autocallable Securities Linked to the S&P 500^® Index Due November 23, 2029

(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 $946.00 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) For more information on the distribution of the securities, see "Supplemental Plan of Distribution" in this pricing supplement. 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.

Investing in the securities involves risks not associated with an investment in conventional debt securities. See "Summary Risk Factors" beginning on page PS-7.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities or determined that this pricing supplement and the accompanying product supplement, underlying 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, underlying supplement, prospectus supplement and prospectus, which can be accessed via the hyperlinks below:

Product Supplement No. EA-02-10 dated March 7, 2023 Underlying Supplement No. 11 dated March 7, 2023
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 underlying supplement contains information about the underlying that is not repeated in this pricing supplement. It is important that you read the accompanying product supplement, underlying supplement, prospectus supplement and prospectus together with this pricing supplement before deciding whether to invest in the securities. Certain terms used but not defined in this pricing supplement are defined in the accompanying product 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 autocall barrier value. The table assumes that the premium applicable to each valuation date will be set at the lowest value indicated under "Key Terms" above. The actual premium applicable to each valuation date will be determined on the pricing date.

If, on any valuation date prior to the final valuation date, the closing value of the underlying is less than the autocall barrier 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 autocall barrier 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. The diagram assumes that the premium applicable to the final valuation date will be set at the lowest value indicated under "Key Terms" above. The actual premium applicable to the final valuation date will be determined on the pricing date.

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.

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, final buffer value or autocall barrier value. For the actual initial underlying value, final buffer value and autocall 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, final buffer value and autocall barrier value, and not the hypothetical values indicated below. For ease of analysis, figures below have been rounded. The examples below assume that the premium applicable to the final valuation date will be set at the lowest value indicated under "Key Terms" above. The actual premium applicable to the final valuation date will be determined on the pricing date.

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 autocall barrier value.

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

= $1,000 + $400

= $1,400

In this scenario, because the final underlying value is greater than the autocall barrier 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 87.00, resulting in a -13.00% underlying return. In this example, the final underlying value is less than the autocall barrier value but greater than the final buffer value.

Payment at maturity per security = $1,000

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 autocall barrier value but not below the final buffer 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 A. The final underlying value is 70.00, resulting in a -30.00% underlying return. In this example, the final underlying value is less than the final buffer value.

Payment at maturity per security = $1,000 + [$1,000 × the buffer rate × (the underlying return + the buffer percentage)]

= $1,000 + [$1,000 × 1.176471 × (-30.00% + 15.00%)]

= $1,000 + [$1,000 × 1.176471 × -15.00%]

= $1,000 + -$176.471

= $823.529

In this scenario, the underlying has depreciated from the initial underlying value to the final underlying value by more than the buffer percentage. As a result, your total return at maturity in this scenario would be negative and would reflect a loss of more than 1% of the stated principal amount of your securities (at a rate equal to the buffer rate) for every 1% by which the underlying declined beyond the buffer percentage.

Example 4-Downside Scenario B. 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 buffer value.

Payment at maturity per security = $1,000 + [$1,000 × the buffer rate × (the underlying return + the buffer percentage)]

= $1,000 + [$1,000 × 1.176471 × (-70.00% + 15.00%)]

= $1,000 + [$1,000 × 1.176471 × -55.00%]

= $1,000 + -$647.059

= $352.941

In this scenario, the underlying has depreciated from the initial underlying value to the final underlying value by more than the buffer percentage. As a result, your total return at maturity in this scenario would be negative and would reflect a loss of more than 1% of the stated principal amount of your securities (at a rate equal to the buffer rate) for every 1% by which the underlying declined beyond the buffer percentage. A comparison of this example with the previous example illustrates the diminishing benefit of the buffer the greater the depreciation of the underlying. The greater the depreciation of the underlying on the final valuation date, the closer your negative return on the securities will be to the depreciation 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.

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.

Information About the S&P 500^® Index

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 markets. It is calculated and maintained by S&P Dow Jones Indices LLC.

Please refer to the section "Equity Index Descriptions- The S&P U.S. Indices" in the accompanying underlying supplement for additional information.

We have derived all information regarding the S&P 500^® Index from publicly available information and have not independently verified any information regarding the S&P 500^® Index. This pricing supplement relates only to the securities and not to the S&P 500^® Index. We make no representation as to the performance of the S&P 500^® Index over the term of the securities.

The securities represent obligations of Citigroup Global Markets Holdings Inc. (guaranteed by Citigroup Inc.) only. The sponsor of the S&P 500^® Index is not involved in any way in this offering and has no obligation relating to the securities or to holders of the securities.

Historical Information

The closing value of the S&P 500^® Index on November 14, 2024 was 5,949.17.

The graph below shows the closing value of the S&P 500^® Index for each day such value was available from January 2, 2014 to November 14, 2024. We obtained the closing values from Bloomberg L.P., without independent verification. You should not take historical closing values as an indication of future performance.

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.

Due to the lack of any controlling legal authority, there is substantial uncertainty regarding the U.S. federal income tax consequences of an investment in the securities. In the opinion of our counsel, Davis Polk & Wardwell LLP, it is reasonable under current law to treat a security as a prepaid forward contract for U.S. federal income tax purposes. However, our counsel has advised us that it is unable to conclude affirmatively that this treatment is more likely than not to be upheld, and that alternative treatments are possible. 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 particular, due to the terms of the securities, there is a substantial risk that the IRS could seek to treat the securities as debt instruments for U.S. federal income tax purposes. In that event, you would be required to accrue into income original issue discount on the securities every year at a "comparable yield" determined as of the time of issuance and recognize all income and gain in respect of the securities as ordinary income. 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 not receive any underwriting fee for any securities sold in the offering.

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 certain terms of the securities have not yet been fixed and 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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