[424B2] Citigroup Inc. Prospectus Supplement

Rhea-AI Filing Summary

Bank of Montreal (BMO) is issuing $1.481 million of Capped Leveraged Buffered S&P 500® Index-Linked Notes due 18 Aug 2027. The $1,000-denominated senior notes pay no interest and the cash payment at maturity depends on S&P 500 performance versus the initial level of 6,263.26.

• Upside exposure: 180 % participation in any index gain, capped at a maximum settlement amount of $1,238.50 once the index rises ≥113.25 % of the initial level (23.85 % maximum return).
• Principal protection band: If the index finishes between 85 % and 100 % of the initial level, investors receive 100 % of principal.
• Downside risk: Below the 85 % buffer, holders lose about 1.1765 % of principal for every 1 % fall, leading to total loss if the index falls to zero.

The estimated initial value is $990.77, lower than the $1,000 offer price, reflecting structuring and hedging costs. The notes are unsecured obligations of BMO, not FDIC/CDIC insured, and will not be exchange-listed; secondary liquidity will rely on BMO Capital Markets. Investors face capped upside, full principal-at-risk beyond the 15 % buffer, complex U.S. tax treatment, and BMO credit risk. CUSIP 06376EQ96.

Insights

Structured Products Analyst

TL;DR Neutral: small issuance offers 180% upside with 15% buffer but capped at 23.85%, principal and liquidity risks remain.

The $1.481 million issuance is immaterial to BMO’s balance sheet, so market impact is negligible. For investors, the structure provides leveraged participation up to 23.85 %, a modest cap compared with four-year equity upside potential. The 15 % buffer gives limited downside protection, after which losses accelerate at 117.65 % of the index decline. No coupon, credit dependence on BMO, estimated value below issue price, and expected illiquidity temper attractiveness. Given these mixed features and the limited size, I classify the filing as neutral for broader equity or credit investors.

The information in this preliminary pricing supplement is not complete and may be changed. A registration statement relating to these securities has been filed with the Securities and Exchange Commission. This preliminary pricing supplement and the accompanying product supplement, prospectus supplement and prospectus are not an offer to sell these securities, nor are they soliciting an offer to buy these securities, in any state where the offer or sale is not permitted. SUBJECT TO COMPLETION, DATED JULY 11, 2025

Citigroup Global Markets Holdings Inc.

July     , 2025 Medium-Term Senior Notes, Series N Pricing Supplement No. 2025-USNCH27559 Filed Pursuant to Rule 424(b)(2) Registration Statement Nos. 333-270327 and 333-270327-01

Autocallable Equity Linked Securities Linked to Micron Technology, Inc. Due July 26, 2028

▪The securities offered by this pricing supplement are unsecured debt securities issued by Citigroup Global Markets Holdings Inc. and guaranteed by Citigroup Inc. The securities offer periodic coupon payments at an annualized rate that is generally higher than the yield on our conventional debt securities of the same maturity. In exchange for this higher yield, you must be willing to accept the risks that (i) the value of what you receive at maturity may be significantly less than the stated principal amount of your securities, and may be zero (excluding the final coupon payment), and (ii) the securities may be automatically called for redemption prior to maturity beginning on the first potential autocall date specified below. Each of these risks will depend on the performance of the underlying specified below. Although you will have downside exposure to the underlying, you will not receive dividends with respect to the underlying or participate in any appreciation of the underlying.

▪Investors in the securities must be willing to accept (i) an investment that may have limited or no liquidity and (ii) the risk of not receiving any payments due under the securities if we and Citigroup Inc. default on our obligations. All payments on the securities are subject to the credit risk of Citigroup Global Markets Holdings Inc. and Citigroup Inc.

KEY TERMS
Issuer:	Citigroup Global Markets Holdings Inc., a wholly owned subsidiary of Citigroup Inc.
Guarantee:	All payments due on the securities are fully and unconditionally guaranteed by Citigroup Inc.
Underlying:	Micron Technology, Inc.
Stated principal amount:	$1,000 per security
Pricing date:	July 21, 2025
Issue date:	July 24, 2025
Valuation date:	July 21, 2028, subject to postponement if such date is not a scheduled trading day or certain market disruption events occur
Maturity date:	Unless earlier redeemed, July 26, 2028
Coupon payments:	On each coupon payment date, unless previously redeemed, the securities will pay a coupon equal to at least 2.50% of the stated principal amount of the securities (equivalent to a coupon rate of at least 10.00% per annum) (to be determined on the pricing date).
Coupon payment dates:	The 26th day of each January, April, July and October beginning in October 2025. If any coupon payment date is not a business day, the payment to be made on that coupon payment date will be made on the next succeeding business day with the same force and effect as if made on that coupon payment date. No interest will accrue as a result of any delayed payment.
Payment at maturity:	If the securities are not automatically redeemed prior to maturity, you will receive at maturity for each security you then hold (in addition to the final coupon payment): ■If the final underlying value is greater than or equal to the final barrier value: $1,000 ■If the final underlying value is less than the final barrier value: $1,000 + ($1,000 × the underlying return) If the securities are not automatically redeemed prior to maturity and the final underlying value is less than the final barrier value, you will receive significantly less than the stated principal amount of your securities, and possibly nothing (other than the final coupon payment), at maturity.
Initial underlying value:	$, the closing value of the underlying on the pricing date
Final underlying value:	The closing value of the underlying on the valuation date
Final barrier value:	$, 60.00% of the initial underlying value
Listing:	The securities will not be listed on any securities exchange
Underwriter:	Citigroup Global Markets Inc. (“CGMI”), an affiliate of the issuer, acting as principal
Underwriting fee and issue price:	Issue price(1)(2)	Underwriting fee(3)	Proceeds to issuer(4)
Per security:	$1,000.00	$28.50	$971.50
Total:	$	$	$

(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 $906.50 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) The issue price for investors purchasing the securities in fee-based advisory accounts will be $971.50 per security. See “Supplemental Plan of Distribution” in this pricing supplement.

(3) CGMI will receive an underwriting fee of up to $28.50 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.

(4) 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-5.

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, 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, prospectus supplement and prospectus, which can be accessed via the hyperlinks below:

Product Supplement No. EA-02-10 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.

Citigroup Global Markets Holdings Inc.

KEY TERMS (continued)
Automatic early redemption:	If, on any potential autocall date, the closing value of the underlying on that potential autocall date is greater than or equal to  the initial underlying value, each security you then hold will be automatically called on that potential autocall date for redemption on the immediately following coupon payment date for an amount in cash equal to $1,000 plus the related coupon payment. The automatic early redemption feature may significantly limit your potential return on the securities. If the underlying performs in a way that would otherwise be favorable, the securities are likely to be automatically called for redemption prior to maturity, cutting short your opportunity to receive coupon payments. The securities may be automatically called for redemption as early as the first potential autocall date specified below.
Potential autocall dates:	July 22, 2026, October 21, 2026, January 21, 2027, April 21, 2027, July 21, 2027, October 21, 2027, January 21, 2028 and April 21, 2028, each subject to postponement as if such date were the valuation date as described in the accompanying product supplement. If a scheduled potential autocall date is postponed by one or more business days, the immediately following coupon payment date will be postponed by an equal number of business days.
Underlying return:	(i) The final underlying value minus the initial underlying value, divided by (ii) the initial underlying value
CUSIP / ISIN:	17333LLF0 / US17333LLF03

PS-2

Citigroup Global Markets Holdings Inc.

Additional Information

General. 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. It is important that you read the accompanying product 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.

Closing Value. The “closing value” of the underlying on any date is the closing price of its underlying shares on such date, as provided in the accompanying product supplement. The “underlying shares” of the underlying are its shares of common stock. Please see the accompanying product supplement for more information.

PS-3

Citigroup Global Markets Holdings Inc.

Hypothetical Examples

The examples below illustrate how to determine the payment at maturity on the securities, assuming the securities are not automatically redeemed prior to maturity. You should understand that the term of the securities, and your opportunity to receive the coupon payments on the securities, may be limited by the automatic early redemption feature of the securities, which is not reflected in the examples below. The outcomes illustrated below are not exhaustive, and your actual payment at maturity on the securities (if the securities are not earlier automatically redeemed) may differ from any example illustrated below. 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 payments 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. The examples below assume that the coupon rate is set at the lowest value indicated on the cover page of this pricing supplement. The actual coupon rate will be determined on the pricing date.

Hypothetical initial underlying value:	$100.00
Hypothetical final barrier value:	$60.00 (60.00% of the hypothetical initial underlying value)

	Hypothetical final underlying value	Hypothetical payment at maturity per $1,000.00 security (excluding the final coupon payment)
Example 1	$110	$1,000.00
Example 2	$45	$450.00
Example 3	$0	$0.00

Example 1: The final underlying value is greater than the final barrier value. Accordingly, at maturity, you would receive the stated principal amount of the securities plus the final coupon payment. You would not participate in the appreciation of the underlying.

Example 2: The final underlying value is less than the final barrier value. Accordingly, at maturity, you would receive a payment per security (excluding the final coupon payment) calculated as follows:

Payment at maturity = $1,000.00 + ($1,000.00 × the underlying return)

= $1,000.00 + ($1,000.00 × -55.00%)

= $1,000.00 + -$550.00

= $450.00

In this scenario, because the final underlying value is less than the final barrier value, you would lose a significant portion of your investment in the securities.

Example 3: The final underlying value is $0.00. Accordingly, at maturity, you would receive a payment per security (excluding the final coupon payment) calculated as follows:

Payment at maturity = $1,000.00 + ($1,000.00 × the underlying return)

= $1,000.00 + ($1,000.00 × -100.00%)

= $1,000.00 + -$1,000.00

= $0.00

In this scenario, you would lose your entire investment in the securities at maturity.

PS-4

Citigroup Global Markets Holdings Inc.

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.

Citigroup Inc. will release quarterly earnings on July 15, 2025, which is during the marketing period and prior to the pricing date of these securities.

■You may lose a significant portion or all of your investment. Unlike conventional debt securities, the securities do not provide for the repayment of the stated principal amount at maturity in all circumstances. If the securities are not automatically redeemed prior to maturity, your payment at maturity will depend on the final underlying value. If the final underlying value is less than the final barrier value, you will lose 1% of the stated principal amount of your securities for every 1% by which the underlying has declined from the initial underlying value. There is no minimum payment at maturity on the securities (excluding the final coupon payment), and you may lose up to all of your investment.

■Higher coupon rates are associated with greater risk. The securities offer coupon payments at an annualized rate that is generally higher than the yield on our conventional debt securities of the same maturity. This higher potential yield is associated with greater levels of expected risk as of the pricing date for the securities, including the risk that the value of what you receive at maturity may be significantly less than the stated principal amount of your securities and may be zero. The volatility of the closing value of the underlying is an important factor affecting these risks. Greater expected volatility of the closing value of the underlying as of the pricing date may result in a higher coupon rate, but would also represent a greater expected likelihood as of the pricing date that the final underlying value will be less than the final barrier value, such that you will not be repaid the stated principal amount of your securities at maturity.

■The securities may be automatically redeemed prior to maturity, limiting your opportunity to receive coupon payments. On any potential autocall date, the securities will be automatically called for redemption if the closing value of the underlying on that potential autocall date is greater than or equal to the initial underlying value. As a result, if the underlying performs in a way that would otherwise be favorable, the securities are likely to be automatically redeemed, cutting short your opportunity to receive coupon payments. If the securities are automatically redeemed prior to maturity, you may not be able to reinvest your funds in another investment that provides a similar yield with a similar level of risk.

■The securities offer downside exposure to the underlying, but no upside exposure to the underlying. You will not participate in any appreciation in the value of the underlying over the term of the securities. Consequently, your return on the securities will be limited to the coupon payments you receive and may be significantly less than the return on the underlying over the term of the securities. In addition, as an investor in the securities, you will not receive any dividends or other distributions or have any other rights with respect to the underlying.

■The performance of the securities will depend on the closing value of the underlying solely on the potential autocall dates and the valuation date, which makes the securities particularly sensitive to volatility in the closing value of the underlying. If the securities are not automatically redeemed prior to maturity, the amount you receive at maturity will depend solely on the closing value of the underlying on the valuation date. Whether the securities will be automatically redeemed prior to maturity will depend on the closing value of the underlying solely on each potential autocall date. As a result, because the performance of the securities depends on the closing value of the underlying on a limited number of dates, the securities will be particularly sensitive to the volatility of the underlying on or near the potential autocall dates and the valuation date. You should understand that the underlying has historically been highly volatile.

■The securities are subject to the credit risk of Citigroup Global Markets Holdings Inc. and Citigroup Inc. If we default on our obligations under the securities and Citigroup Inc. defaults on its guarantee obligations, you may not receive anything owed to you under the securities.

■The securities will not be listed on any securities exchange and you may not be able to sell them prior to maturity. The securities will not be listed on any securities exchange. Therefore, there may be little or no secondary market for the securities. CGMI currently intends to make a secondary market in relation to the securities and to provide an indicative bid price for the securities on a daily basis. Any indicative bid price for the securities provided by CGMI will be determined in CGMI’s sole discretion, taking into account prevailing market conditions and other relevant factors, and will not be a representation by CGMI that the securities can be sold at that price, or at all. CGMI may suspend or terminate making a market and providing indicative bid prices without notice, at any time and for any reason. If CGMI suspends or terminates making a market, there may be no secondary market at all for the securities because it is likely that CGMI will be the only broker-dealer that is willing to buy your securities prior to maturity. Accordingly, an investor must be prepared to hold the securities until maturity.

■The estimated value of the securities on the pricing date, based on CGMI’s proprietary pricing models and our internal funding rate, will be less than the issue price. The difference is attributable to certain costs associated with selling, structuring and hedging the securities that are included in the issue price. These costs include (i) any selling concessions or other fees paid in connection with the offering of the securities, (ii) hedging and other costs incurred by us and our affiliates in connection with the offering of the securities and

PS-5

Citigroup Global Markets Holdings Inc.

(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.

■The estimated value of the securities was determined for us by our affiliate using proprietary pricing models. CGMI derived the estimated value disclosed on the cover page of this pricing supplement from its proprietary pricing models. In doing so, it may have made discretionary judgments about the inputs to its models, such as the volatility of the closing value of the underlying, the dividend yield on the underlying and interest rates. CGMI’s views on these inputs may differ from your or others’ views, and as an underwriter in this offering, CGMI’s interests may conflict with yours. Both the models and the inputs to the models may prove to be wrong and therefore not an accurate reflection of the value of the securities. Moreover, the estimated value of the securities set forth on the cover page of this pricing supplement may differ from the value that we or our affiliates may determine for the securities for other purposes, including for accounting purposes. You should not invest in the securities because of the estimated value of the securities. Instead, you should be willing to hold the securities to maturity irrespective of the initial estimated value.

■The estimated value of the securities would be lower if it were calculated based on our secondary market rate. The estimated value of the securities included in this pricing supplement is calculated based on our internal funding rate, which is the rate at which we are willing to borrow funds through the issuance of the securities. Our internal funding rate is generally lower than our secondary market rate, which is the rate that CGMI will use in determining the value of the securities for purposes of any purchases of the securities from you in the secondary market. If the estimated value included in this pricing supplement were based on our secondary market rate, rather than our internal funding rate, it would likely be lower. We determine our internal funding rate based on factors such as the costs associated with the securities, which are generally higher than the costs associated with conventional debt securities, and our liquidity needs and preferences. Our internal funding rate is not an interest rate that is payable on the securities.

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.

■The estimated value of the securities is not an indication of the price, if any, at which CGMI or any other person may be willing to buy the securities from you in the secondary market. Any such secondary market price will fluctuate over the term of the securities based on the market and other factors described in the next risk factor. Moreover, unlike the estimated value included in this pricing supplement, any value of the securities determined for purposes of a secondary market transaction will be based on our secondary market rate, which will likely result in a lower value for the securities than if our internal funding rate were used. In addition, any secondary market price for the securities will be reduced by a bid-ask spread, which may vary depending on the aggregate stated principal amount of the securities to be purchased in the secondary market transaction, and the expected cost of unwinding related hedging transactions. As a result, it is likely that any secondary market price for the securities will be less than the issue price.

■The value of the securities prior to maturity will fluctuate based on many unpredictable factors. The value of your securities prior to maturity will fluctuate based on the closing value of the underlying, the volatility of the closing value of the underlying, the dividend yield on the underlying, interest rates generally, the time remaining to maturity and our and Citigroup Inc.’s creditworthiness, as reflected in our secondary market rate, among other factors described under “Risk Factors Relating to the Securities—Risk Factors Relating to All Securities—The value of your securities prior to maturity will fluctuate based on many unpredictable factors” in the accompanying product supplement. Changes in the closing value of the underlying may not result in a comparable change in the value of your securities. You should understand that the value of your securities at any time prior to maturity may be significantly less than the issue price.

■Immediately following issuance, any secondary market bid price provided by CGMI, and the value that will be indicated on any brokerage account statements prepared by CGMI or its affiliates, will reflect a temporary upward adjustment. The amount of this temporary upward adjustment will steadily decline to zero over the temporary adjustment period. See “Valuation of the Securities” in this pricing supplement.

■Our offering of the securities is not a recommendation of the underlying. The fact that we are offering the securities does not mean that we believe that investing in an instrument linked to the underlying is likely to achieve favorable returns. In fact, as we are part of a global financial institution, our affiliates may have positions (including short positions) in the underlying or in instruments related to the underlying, and may publish research or express opinions, that in each case are inconsistent with an investment linked to the underlying. These and other activities of our affiliates may affect the closing value of the underlying in a way that negatively affects the value of and your return on the securities.

■The closing value of the underlying may be adversely affected by our or our affiliates’ hedging and other trading activities. We expect to hedge our obligations under the securities through CGMI or other of our affiliates, who may take positions in the underlying or in financial instruments related to the underlying and may adjust such positions during the term of the securities. Our affiliates also take positions in the underlying or in financial instruments related to the underlying on a regular basis (taking long or short positions or both), for their accounts, for other accounts under their management or to facilitate transactions on behalf of customers. These activities could affect the closing value of the underlying in a way that negatively affects the value of and your return on the securities. They could also result in substantial returns for us or our affiliates while the value of the securities declines.

■We and our affiliates may have economic interests that are adverse to yours as a result of our affiliates’ business activities. Our affiliates engage in business activities with a wide range of companies. These activities include extending loans, making and facilitating

PS-6

Citigroup Global Markets Holdings Inc.

investments, underwriting securities offerings and providing advisory services. These activities could involve or affect the underlying in a way that negatively affects the value of and your return on the securities. They could also result in substantial returns for us or our affiliates while the value of the securities declines. In addition, in the course of this business, we or our affiliates may acquire non-public information, which will not be disclosed to you.

■The calculation agent, which is an affiliate of ours, will make important determinations with respect to the securities. If certain events occur during the term of the securities, such as market disruption events and other events with respect to the underlying, CGMI, as calculation agent, will be required to make discretionary judgments that could significantly affect your return on the securities. In making these judgments, the calculation agent’s interests as an affiliate of ours could be adverse to your interests as a holder of the securities. See “Risk Factors Relating to the Securities—Risk Factors Relating to All Securities—The calculation agent, which is an affiliate of ours, will make important determinations with respect to the securities” in the accompanying product supplement.

■Even if the underlying pays a dividend that it identifies as special or extraordinary, no adjustment will be required under the securities for that dividend unless it meets the criteria specified in the accompanying product supplement. In general, an adjustment will not be made under the terms of the securities for any cash dividend paid by the underlying unless the amount of the dividend per share, together with any other dividends paid in the same quarter, exceeds the dividend paid per share in the most recent quarter by an amount equal to at least 10% of the closing value of the underlying on the date of declaration of the dividend. Any dividend will reduce the closing value of the underlying by the amount of the dividend per share. If the underlying pays any dividend for which an adjustment is not made under the terms of the securities, holders of the securities will be adversely affected. See “Description of the Securities—Certain Additional Terms for Securities Linked to an Underlying Company or an Underlying ETF—Dilution and Reorganization Adjustments—Certain Extraordinary Cash Dividends” in the accompanying product supplement.

■The securities will not be adjusted for all events that may have a dilutive effect on or otherwise adversely affect the closing value of the underlying. For example, we will not make any adjustment for ordinary dividends or extraordinary dividends that do not meet the criteria described above, partial tender offers or additional underlying share issuances. Moreover, the adjustments we do make may not fully offset the dilutive or adverse effect of the particular event. Investors in the securities may be adversely affected by such an event in a circumstance in which a direct holder of the underlying shares would not.

■The securities may become linked to an underlying other than the original underlying upon the occurrence of a reorganization event or upon the delisting of the underlying shares. For example, if the underlying enters into a merger agreement that provides for holders of the underlying shares to receive shares of another entity and such shares are marketable securities, the closing value of the underlying following consummation of the merger will be based on the value of such other shares. Additionally, if the underlying shares are delisted, the calculation agent may select a successor underlying. See “Description of the Securities—Certain Additional Terms for Securities Linked to an Underlying Company or an Underlying ETF” in the accompanying product supplement.

■If the underlying shares are delisted, we may call the securities prior to maturity for an amount that may be less than the stated principal amount. If we exercise this call right, you will receive the amount described under “Description of the Securities—Certain Additional Terms for Securities Linked to an Underlying Company or an Underlying ETF—Delisting of an Underlying Company” in the accompanying product supplement. This amount may be less, and possibly significantly less, than the stated principal amount of the securities.

■The U.S. federal tax consequences of an investment in the securities are unclear. There is no direct legal authority regarding the proper U.S. federal tax treatment of the 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 the securities are uncertain, and the IRS or a court might not agree with the treatment of the securities as described in “United States Federal Tax Considerations” below. If the IRS were successful in asserting an alternative treatment of the securities, the tax consequences of the ownership and disposition of the securities might be materially and adversely affected. Moreover, future legislation, Treasury regulations or IRS guidance could adversely affect the U.S. federal tax treatment of the securities, possibly retroactively.

As described in “United States Federal Tax Considerations” below, in connection with any information reporting requirements we may have in respect of the securities under applicable law, we intend to treat a portion of each coupon payment as attributable to interest and the remainder to option premium. However, in light of the uncertain treatment of the securities, it is possible that other persons having withholding or information reporting responsibility in respect of the securities may treat a security differently, for instance, by treating the entire coupon payment as ordinary income at the time received or accrued by a holder and/or treating some or all of each coupon payment on a security to a non-U.S. investor as subject to withholding tax at a rate of 30%.

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

PS-7

Citigroup Global Markets Holdings Inc.

Information About Micron Technology, Inc.

Micron Technology, Inc., through its subsidiaries, manufactures and markets dynamic random access memory chips (DRAMs), static random access memory chips (SRAMs), flash memory, semiconductor components, and memory modules. The underlying shares of Micron Technology, Inc. are registered under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). Information provided to or filed with the SEC by Micron Technology, Inc. pursuant to the Exchange Act can be located by reference to the SEC file number 001-10658 through the SEC’s website at http://www.sec.gov. In addition, information regarding Micron Technology, Inc. may be obtained from other sources including, but not limited to, press releases, newspaper articles and other publicly disseminated documents. The underlying shares of Micron Technology, Inc. trade on the NASDAQ Global Select Market under the ticker symbol “MU.”

We have derived all information regarding Micron Technology, Inc. from publicly available information and have not independently verified any information regarding Micron Technology, Inc. This pricing supplement relates only to the securities and not to Micron Technology, Inc. We make no representation as to the performance of Micron Technology, Inc. over the term of the securities.

The securities represent obligations of Citigroup Global Markets Holdings Inc. (guaranteed by Citigroup Inc.) only. Micron Technology, Inc. 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 Micron Technology, Inc. on July 10, 2025 was $123.11.

The graph below shows the closing value of Micron Technology, Inc. for each day such value was available from January 2, 2015 to July 10, 2025. We obtained the closing values from Bloomberg L.P., without independent verification. If certain corporate transactions occurred during the historical period shown below, including, but not limited to, spin-offs or mergers, then the closing values shown below for the period prior to the occurrence of any such transaction have been adjusted by Bloomberg L.P. as if any such transaction had occurred prior to the first day in the period shown below. You should not take historical closing values as an indication of future performance.

Micron Technology, Inc. – Historical Closing Values January 2, 2015 to July 10, 2025

PS-8

Citigroup Global Markets Holdings Inc.

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 tax consequences of an investment in the securities. In connection with any information reporting requirements we may have in respect of the securities under applicable law, we intend (in the absence of an administrative determination or judicial ruling to the contrary) to treat a security as a put option (the “Put Option”) written by you with respect to the underlying shares, secured by a cash deposit equal to the stated principal amount of the security (the “Deposit”). In the opinion of our counsel, Davis Polk & Wardwell LLP, this treatment of the securities is reasonable under current law; 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. Under this treatment:

●a portion of each coupon payment made with respect to the securities will be attributable to interest on the Deposit; and

●the remainder will represent premium attributable to your grant of the Put Option (“Put Premium”).

We will specify in the final pricing supplement the portion of each coupon payment that we will allocate to interest on the Deposit and to Put Premium, respectively.

Assuming the treatment of a security as a Put Option and a Deposit is respected, amounts treated as interest on the Deposit should be taxed as ordinary interest income, while the Put Premium should not be taken into account prior to maturity or disposition of the securities. See “United States Federal Tax Considerations—Tax Consequences to U.S. Holders” in the accompanying product supplement.

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 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 the section of the accompanying product supplement entitled “United States Federal Tax Considerations,” if you are a Non-U.S. Holder (as defined in the accompanying product supplement) of the securities, under current law 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— Dividend Equivalents under Section 871(m) of the Code” in the accompanying product supplement, Section 871(m) of the Internal Revenue Code of 1986, as amended, 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 (“Underlying Securities”) or indices that include Underlying Securities. Section 871(m) generally applies to instruments that substantially replicate the economic performance of one or more Underlying Securities, 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 Underlying Security 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.

While we currently do not intend to withhold on payments on the securities to Non-U.S. Holders (subject to compliance with the applicable certification requirements and the discussion in the accompanying product supplement regarding “FATCA”), in light of the uncertain treatment of the securities other persons having withholding or information reporting responsibility in respect of the securities may treat some or all of each coupon payment on a security as subject to withholding tax at a rate of 30%. Moreover, it is possible that in the future we may determine that we should withhold at a rate of 30% on coupon payments on 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.

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Citigroup Global Markets Holdings Inc.

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 $28.50 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 $28.50 for each security they sell to accounts other than fee-based advisory accounts.  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 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 three 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 three-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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