[424B2] Citigroup Inc. Prospectus Supplement

Rhea-AI Filing Summary

Citigroup Global Markets Holdings Inc., guaranteed by Citigroup Inc., is offering unsecured Market-Linked Securities that mature on 24-Jun-2027 and are linked to the worst performing of the Nasdaq-100 Index® and the S&P 500® Index.

Key structural terms

• Denomination: $1,000 per note.
• Pricing / Issue dates: 18-Jul-2025 / 23-Jul-2025.
• Upside: 100 % participation in the index appreciation of the worst performer, capped at a Maximum Return ≥ $143 (≥ 14.30 %).
• Downside: 1-for-1 exposure to any decline in the worst performer, but losses are limited to −$50 (−5 %) of principal at maturity.
• No interim coupons, no dividend pass-through, and no principal guarantee.
• Credit exposure: payments depend on the creditworthiness of Citigroup Global Markets Holdings Inc. and Citigroup Inc.
• Liquidity: the notes will not be listed; secondary market, if any, will be made on a best-efforts basis by CGMI.
• Issue price vs. value: investors pay $1,000; the estimated value on the pricing date is expected to be ≥ $917 (≈ 9 % discount to par) reflecting structuring and hedging costs.
• Underwriting fee: up to $22.25 (2.225 %) per note; proceeds to issuer ≈ $977.75.

Illustrative outcomes

• If the worst index rises 5 % → investor receives $1,050.
• If the worst index rises ≥ 14.30 % → payoff is capped at ≈ $1,143.
• If the worst index falls 2 % → investor receives $980.
• If the worst index falls ≥ 5 % → investor receives $950 (maximum loss).

Risk highlights

• Potential loss of up to 5 % of principal; no interest income.
• Performance driven by a single observation (valuation date), exposing investors to adverse one-day moves.
• Return is limited; the structure will underperform a direct equity investment if index gains exceed the cap or if dividends are material.
• The embedded credit, liquidity, valuation and model risks outlined in pages PS-5 to PS-7 of the supplement apply in full.

Investor profile: suited to investors seeking moderate equity exposure with clearly defined downside (-5 %) and prepared to accept a capped upside, no income, complex tax treatment (contingent payment debt instrument), and the credit risk of Citigroup.

Positive

• Downside limited to 5 % of principal, offering partial protection compared with traditional equity exposure.
• 100 % upside participation until the cap allows investors to capture moderate index gains.
• Full Citigroup Inc. guarantee provides senior unsecured claim on a large, investment-grade bank.

Negative

• Upside is capped at ≥ 14.3 %; investors forgo further appreciation and all dividends.
• No interim interest and possible real-value erosion due to inflation.
• Estimated value (≥ $917) is materially below the $1,000 issue price, reflecting structuring costs.
• Liquidity risk: unlisted security; any dealer bid may be well below theoretical value.
• Credit exposure to Citigroup; default would nullify protection features.

Insights

Structured-Products Analyst

TL;DR: Two-year worst-of note offers 100 % upside to ≥ 14.3 % and capped 5 % downside; no coupons, credit & liquidity risks remain.

The product is a short-dated, partially-protected equity note. The 5 % maximum loss meaningfully reduces tail risk versus direct equity exposure, yet the 14.3 % cap (≈ 6.9 % CAGR) limits upside in a still-volatile market. Because payoff is based on the worst index, correlation risk is material; divergent index performance can quickly drive the effective return. Investors effectively pay ~9 % premium over model value (issue vs. estimated value), and secondary liquidity is dealer-driven. From Citigroup’s standpoint, this is ordinary funding at attractive spreads, so the filing is not materially impactful for shareholders.

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, underlying 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-USNCH27555 Filed Pursuant to Rule 424(b)(2) Registration Statement Nos. 333-270327 and 333-270327-01

Market-Linked Securities Linked to the Worst Performing of the Nasdaq-100 Index^® and the S&P 500^® Index Due June 24, 2027

▪The securities offered by this pricing supplement are unsecured debt securities issued by Citigroup Global Markets Holdings Inc. and guaranteed by Citigroup Inc. Unlike conventional debt securities, the securities do not pay interest and do not guarantee the full repayment of principal at maturity. Instead, the securities offer the potential for a return at maturity based on the performance of the worst performing of the underlyings specified below from its initial underlying value to its final underlying value.

▪If the worst performing underlying appreciates from its initial underlying value to its final underlying value, you will receive a positive return at maturity equal to that appreciation multiplied by the upside participation rate, subject to the maximum return at maturity specified below. However, if the worst performing underlying depreciates from its initial underlying value to its final underlying value, you will incur a loss at maturity equal to that depreciation, subject to the maximum loss at maturity. Even if the worst performing underlying appreciates from its initial underlying value to its final underlying value, so that you do receive a positive return at maturity, there is no assurance that your total return at maturity on the securities will compensate you for the effects of inflation or be as great as the yield you could have achieved on a conventional debt security of ours of comparable maturity.

▪In exchange for the capped loss potential if the worst performing underlying depreciates, investors in the securities must be willing to forgo (i) any return on the securities in excess of the maximum return at maturity and (ii) dividends with respect to any underlying. If the worst performing underlying does not appreciate from its initial underlying value to its final underlying value, you will not receive any return on your investment in the securities, and you may lose up to the maximum loss at maturity.

▪You will be subject to risks associated with each of the underlyings and will be negatively affected by adverse movements in any one of the underlyings.

▪In order to obtain the modified exposure to the worst performing underlying that the securities provide, investors must be willing to accept (i) an investment that may have limited or no liquidity and (ii) the risk of not receiving any amount 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.
Underlyings:	Underlying Initial underlying value* Nasdaq-100 Index® S&P 500® Index *For each underlying, its closing value on the pricing date
Stated principal amount:	$1,000 per security
Pricing date:	July 18, 2025
Issue date:	July 23, 2025
Valuation date:	June 21, 2027, subject to postponement if such date is not a scheduled trading day or certain market disruption events occur
Maturity date:	June 24, 2027
Payment at maturity:	You will receive at maturity for each security you then hold: ●If the final underlying value of the worst performing underlying is greater than its initial underlying value: $1,000 + the return amount, subject to the maximum return at maturity ●If the final underlying value of the worst performing underlying is less than or equal to its initial underlying value: $1,000 + ($1,000 × the underlying return of the worst performing underlying), subject to the maximum loss at maturity If the worst performing underlying depreciates from its initial underlying value to its final underlying value, you will be exposed to that depreciation up to the maximum loss at maturity. You should not invest in the securities unless you are willing and able to bear the risk of losing up to the maximum loss at maturity.
Final underlying value:	For each underlying, its closing value on the valuation date
Return amount:	$1,000 × the underlying return of the worst performing underlying × the upside participation rate
Upside participation rate:	100.00%
Worst performing underlying:	The underlying with the lowest underlying return
Underlying return:	For each underlying, (i) its final underlying value minus its initial underlying value, divided by (ii) its initial underlying value
Maximum return at maturity:	The maximum return at maturity will be determined on the pricing date and will be at least $143.00 per security (at least 14.30% of the stated principal amount). The payment at maturity per security will not exceed the stated principal amount plus the maximum return at maturity.
Maximum loss at maturity:	$50.00 per security (5.00% of the stated principal amount). The maximum loss at maturity represents the maximum loss that may be realized at maturity under the terms of the securities (that is, the maximum amount by which the stated payment at maturity may be less than the stated principal amount). If you sell the securities prior to maturity, or if we and Citigroup Inc. default on our obligations under the securities, you may incur a greater loss on your investment.
Listing:	The securities will not be listed on any securities exchange
CUSIP / ISIN:	17333LKR5 / US17333LKR59
Underwriter:	Citigroup Global Markets Inc. (“CGMI”), an affiliate of the issuer, acting as principal
Underwriting fee and issue price:	Issue price(1)	Underwriting fee(2)	Proceeds to issuer(3)
Per security:	$1,000.00	$22.25	$977.75
Total:	$	$	$

(1) Citigroup Global Markets Holdings Inc. currently expects that the estimated value of the securities on the pricing date will be at least $917.00 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 $22.25 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-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, 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.

Citigroup Global Markets Holdings Inc.

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 each 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 each underlying. The accompanying underlying supplement contains information about each 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.

Payout Diagram

The diagram below illustrates your payment at maturity for a range of hypothetical underlying returns of the worst performing underlying. The diagram assumes that the maximum return at maturity will be set at the lowest value indicated on the cover page of this pricing supplement. The actual maximum return at maturity will be determined on the pricing date.

Investors in the securities will not receive any dividends with respect to the underlyings. 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 underlyings” below.

Payout Diagram
n The Securities	n The Worst Performing Underlying

PS-2

Citigroup Global Markets Holdings Inc.

Hypothetical Examples

The examples below illustrate how to determine the payment at maturity on the securities, assuming the various hypothetical final underlying values indicated below. The examples are solely for illustrative purposes, do not show all possible outcomes and are not a prediction of what the actual payment at maturity on the securities will be. The actual payment at maturity will depend on the actual final underlying value of the worst performing underlying.

The examples below are based on the following hypothetical values and do not reflect the actual initial underlying values of the underlyings. For the actual initial underlying value of each underlying, 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 of each underlying, and not the hypothetical values indicated below. For ease of analysis, figures below have been rounded. The examples below assume that the maximum return at maturity will be set at the lowest value indicated on the cover page of this pricing supplement. The actual maximum return at maturity will be determined on the pricing date.

Underlying	Hypothetical initial underlying value
Nasdaq-100 Index®	100.00
S&P 500® Index	100.00

Example 1—Upside Scenario A. The final underlying value of the worst performing underlying is 105.00, resulting in a 5.00% underlying return for the worst performing underlying. In this example, the final underlying value of the worst performing underlying is greater than its initial underlying value.

Underlying	Hypothetical final underlying value	Hypothetical underlying return
Nasdaq-100 Index® *	105.00	5.00%
S&P 500® Index	150.00	50.00%

* Worst performing underlying

Payment at maturity per security = $1,000 + the return amount, subject to the maximum return at maturity

= $1,000 + ($1,000 × the underlying return of the worst performing underlying × the upside participation rate), subject to the maximum return at maturity

= $1,000 + ($1,000 × 5.00% × 100.00%), subject to the maximum return at maturity

= $1,000 + $50.00, subject to the maximum return at maturity

= $1,050.00

In this scenario, the worst performing underlying has appreciated from its initial underlying value to its final underlying value, and the underlying return of the worst performing underlying multiplied by the upside participation rate is less than the maximum return at maturity. As a result, your total return at maturity would equal the underlying return of the worst performing underlying multiplied by the upside participation rate.

Example 2—Upside Scenario B. The final underlying value of the worst performing underlying is 150.00, resulting in a 50.00% underlying return for the worst performing underlying. In this example, the final underlying value of the worst performing underlying is greater than its initial underlying value.

Underlying	Hypothetical final underlying value	Hypothetical underlying return
Nasdaq-100 Index®	170.00	70.00%
S&P 500® Index*	150.00	50.00%

* Worst performing underlying

Payment at maturity per security = $1,000 + the return amount, subject to the maximum return at maturity

= $1,000 + ($1,000 × the underlying return of the worst performing underlying × the upside participation rate), subject to the maximum return at maturity

= $1,000 + ($1,000 × 50.00% × 100.00%), subject to the maximum return at maturity

= $1,000 + $500.00, subject to the maximum return at maturity

= $1,143.00

In this scenario, the worst performing underlying has appreciated from its initial underlying value to its final underlying value, but the underlying return of the worst performing underlying multiplied by the upside participation rate would exceed the maximum return at maturity. As a result, your total return at maturity in this scenario would be limited to the maximum return at maturity, and an investment in the securities would underperform a hypothetical alternative investment providing 1-to-1 exposure to the appreciation of the worst performing underlying without a maximum return.

Example 3—Downside Scenario A. The final underlying value of the worst performing underlying is 98.00, resulting in a -2.00% underlying return for the worst performing underlying.

Underlying	Hypothetical final underlying value	Hypothetical underlying return
Nasdaq-100 Index® *	98.00	-2.00%
S&P 500® Index	105.00	5.00%

* Worst performing underlying

PS-3

Citigroup Global Markets Holdings Inc.

Payment at maturity per security = $1,000 + ($1,000 × the underlying return of the worst performing underlying), subject to the maximum loss at maturity

= $1,000 + ($1,000 × -2.00%), subject to the maximum loss at maturity

= $1,000 + -$20.00, subject to the maximum loss at maturity

= $980.00, subject to the maximum loss at maturity

= $980.00

In this scenario, the worst performing underlying has depreciated from its initial underlying value to its final underlying value, but not by more than 5.00%. As a result, your payment at maturity would reflect 1-to-1 exposure to the negative performance of the worst performing underlying and you would incur a loss at maturity equal to the depreciation of the worst performing underlying.

Example 4—Downside Scenario B. The final underlying value of the worst performing underlying is 80.00, resulting in a -20.00% underlying return for the worst performing underlying.

Underlying	Hypothetical final underlying value	Hypothetical underlying return
Nasdaq-100 Index®	120.00	20.00%
S&P 500® Index*	80.00	-20.00%

* Worst performing underlying

Payment at maturity per security = $1,000 + ($1,000 × the underlying return of the worst performing underlying), subject to the maximum loss at maturity

= $1,000 + ($1,000 × -20.00%), subject to the maximum loss at maturity

= $1,000 + -$200.00, subject to the maximum loss at maturity

= $800.00, subject to the maximum loss at maturity

= $950

In this scenario, the worst performing underlying has depreciated from its initial underlying value to its final underlying value by more than 5.00%. As a result, you would incur a loss at maturity equal to the maximum loss 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 each 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 not receive any return on your investment in the securities and may lose up to the maximum loss at maturity. You will receive a positive return on your investment in the securities only if the worst performing underlying appreciates from its initial underlying value to its final underlying value. If the final underlying value of the worst performing underlying is less than its initial underlying value, you will lose 1% of the stated principal amount of the securities for every 1% by which its final underlying value is less than its initial underlying value, subject to the maximum loss at maturity. As the securities do not pay any interest, if the worst performing underlying does not appreciate sufficiently from its initial underlying value to its final underlying value over the term of the securities or if the worst performing underlying depreciates from its initial underlying value to its final underlying value, the overall return at maturity on the securities may be less than the amount that would be paid on our conventional debt securities of comparable maturity.

■Although the securities limit your loss to the maximum loss at maturity, you may nevertheless suffer additional losses on your investment in real value terms if the worst performing underlying declines or does not appreciate from its initial underlying value to its final underlying value. This is because inflation may cause the real value of the stated principal amount to be less at maturity than it is at the time you invest, and because an investment in the securities represents a forgone opportunity to invest in an alternative asset that does generate a positive real return. This potential loss in real value terms is significant given the term of the securities. You should carefully consider whether an investment that may not provide for any return on your investment, or may provide a return that is lower than the return on alternative investments, is appropriate for you. In addition, the maximum loss at maturity applies only at maturity. If you sell your securities prior to maturity, the price you receive may result in a loss that is significantly greater than the maximum loss at maturity.

■Your potential return on the securities is limited. Your potential total return on the securities at maturity is limited to the maximum return at maturity, even if the worst performing underlying appreciates by significantly more than the maximum return at maturity. If the worst performing underlying appreciates by more than the maximum return at maturity, the securities will underperform an alternative investment providing 1-to-1 exposure to the performance of the worst performing underlying. When lost dividends are taken into account, the securities may underperform an alternative investment providing 1-to-1 exposure to the performance of the worst performing underlying even if the worst performing underlying appreciates by less than the maximum return at maturity.

■The securities do not pay interest. Unlike conventional debt securities, the securities do not pay interest or any other amounts prior to maturity. You should not invest in the securities if you seek current income during the term of the securities.

■The securities are subject to heightened risk because they have multiple underlyings. The securities are more risky than similar investments that may be available with only one underlying. With multiple underlyings, there is a greater chance that any one underlying will perform poorly, adversely affecting your return on the securities.

■The securities are subject to the risks of each of the underlyings and will be negatively affected if any one underlying performs poorly. You are subject to risks associated with each of the underlyings. If any one underlying performs poorly, you will be negatively affected. The securities are not linked to a basket composed of the underlyings, where the blended performance of the underlyings would be better than the performance of the worst performing underlying alone. Instead, you are subject to the full risks of whichever of the underlyings is the worst performing underlying.

■You will not benefit in any way from the performance of any better performing underlying. The return on the securities depends solely on the performance of the worst performing underlying, and you will not benefit in any way from the performance of any better performing underlying.

■You will be subject to risks relating to the relationship between the underlyings. It is preferable from your perspective for the underlyings to be correlated with each other, in the sense that their closing values tend to increase or decrease at similar times and by similar magnitudes. By investing in the securities, you assume the risk that the underlyings will not exhibit this relationship. The less correlated the underlyings, the more likely it is that any one of the underlyings will perform poorly over the term of the securities. All that is necessary for the securities to perform poorly is for one of the underlyings to perform poorly. It is impossible to predict what the relationship between the underlyings will be over the term of the securities. The underlyings differ in significant ways and, therefore, may not be correlated with each other.

■You will not receive dividends or have any other rights with respect to the underlyings. You will not receive any dividends with respect to the underlyings. This lost dividend yield may be significant over the term of the securities. The payment scenarios described in

PS-5

Citigroup Global Markets Holdings Inc.

this pricing supplement do not show any effect of such lost dividend yield over the term of the securities. In addition, you will not have voting rights or any other rights with respect to the underlyings or the stocks included in the underlyings.

■Your payment at maturity depends on the closing value of the worst performing underlying on a single day. Because your payment at maturity depends on the closing value of the worst performing underlying solely on the valuation date, you are subject to the risk that the closing value of the worst performing underlying on that day may be lower, and possibly significantly lower, than on one or more other dates during the term of the securities. If you had invested in another instrument linked to the worst performing underlying that you could sell for full value at a time selected by you, or if the payment at maturity were based on an average of closing values of the worst performing underlying, you might have achieved better returns.

■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 (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, and correlation between, the closing values of the underlyings, dividend yields on the underlyings 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 values of the underlyings, the volatility of, and correlation between, the closing values of the

PS-6

Citigroup Global Markets Holdings Inc.

underlyings, dividend yields on the underlyings, 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 values of the underlyings 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 any underlying. The fact that we are offering the securities does not mean that we believe that investing in an instrument linked to the underlyings 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 underlyings or in instruments related to the underlyings, and may publish research or express opinions, that in each case are inconsistent with an investment linked to the underlyings. These and other activities of our affiliates may affect the closing values of the underlyings in a way that negatively affects the value of and your return on the securities.

■The closing value of an 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 underlyings or in financial instruments related to the underlyings and may adjust such positions during the term of the securities. Our affiliates also take positions in the underlyings or in financial instruments related to the underlyings 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 values of the underlyings 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 investments, underwriting securities offerings and providing advisory services. These activities could involve or affect the underlyings 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 an 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.

■Changes that affect the underlyings may affect the value of your securities. The sponsors of the underlyings may at any time make methodological changes or other changes in the manner in which they operate that could affect the values of the underlyings. We are not affiliated with any such underlying sponsor and, accordingly, we have no control over any changes any such sponsor may make. Such changes could adversely affect the performance of the underlyings and the value of and your return on the securities.

PS-7

Citigroup Global Markets Holdings Inc.

Information About the Nasdaq-100 Index^®

The Nasdaq-100 Index^® is a modified market capitalization-weighted index of stocks of the 100 largest non-financial companies listed on the Nasdaq Stock Market. All stocks included in the Nasdaq-100 Index^® are traded on a major U.S. exchange. The Nasdaq-100 Index^® was developed by the Nasdaq Stock Market, Inc. and is calculated, maintained and published by Nasdaq, Inc.

Please refer to the section “Equity Index Descriptions— The Nasdaq-100 Index^®” in the accompanying underlying supplement for additional information.

We have derived all information regarding the Nasdaq-100 Index^® from publicly available information and have not independently verified any information regarding the Nasdaq-100 Index^®. This pricing supplement relates only to the securities and not to the Nasdaq-100 Index^®. We make no representation as to the performance of the Nasdaq-100 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 Nasdaq-100 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 Nasdaq-100 Index^® on July 10, 2025 was 22,829.26.

The graph below shows the closing value of the Nasdaq-100 Index^® 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. You should not take historical closing values as an indication of future performance.

Nasdaq-100 Index^® – Historical Closing Values January 2, 2015 to July 10, 2025

PS-8

Citigroup Global Markets Holdings Inc.

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 July 10, 2025 was 6,280.46.

The graph below shows the closing value of the S&P 500^® Index 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. You should not take historical closing values as an indication of future performance.

S&P 500^® Index – Historical Closing Values January 2, 2015 to July 10, 2025

PS-9

Citigroup Global Markets Holdings Inc.

United States Federal Income Tax Considerations

Prospective investors should note that the section entitled “United States Federal Tax Considerations” in the accompanying product supplement does not apply to the securities issued under this pricing supplement and is superseded by the following discussion.

In the opinion of our counsel, Davis Polk & Wardwell LLP, which is based on current market conditions, the securities should be treated as “contingent payment debt instruments” for U.S. federal income tax purposes, as described in the section of the accompanying prospectus supplement called “United States Federal Tax Considerations—Tax Consequences to U.S. Holders—Notes Treated as Contingent Payment Debt Instruments,” and the remaining discussion is based on this treatment.

If you are a U.S. Holder (as defined in the accompanying prospectus supplement), you will be required to recognize interest income during the term of the securities at the “comparable yield,” which generally is the yield at which we could issue a fixed-rate debt instrument with terms similar to those of the securities, including the level of subordination, term, timing of payments and general market conditions, but excluding any adjustments for the riskiness of the contingencies or the liquidity of the securities. We are required to construct a “projected payment schedule” in respect of the securities representing a payment the amount and timing of which would produce a yield to maturity on the securities equal to the comparable yield. Assuming you hold the securities until their maturity, the amount of interest you include in income based on the comparable yield in the taxable year in which the securities mature will be adjusted upward or downward to reflect the difference, if any, between the actual and projected payment on the securities at maturity as determined under the projected payment schedule.

Upon the sale, exchange or retirement of the securities prior to maturity, you generally will recognize gain or loss equal to the difference between the proceeds received and your adjusted tax basis in the securities. Your adjusted tax basis will equal your purchase price for the securities, increased by interest previously included in income on the securities. Any gain generally will be treated as ordinary income, and any loss generally will be treated as ordinary loss to the extent of prior interest inclusions on the security and as capital loss thereafter.

We have determined that the comparable yield for a security is a rate of    %, compounded semi-annually, and that the projected payment schedule with respect to a security consists of a single payment of $    at maturity.

Neither the comparable yield nor the projected payment schedule constitutes a representation by us regarding the actual amount that we will pay on the securities.

Non-U.S. Holders. Subject to the discussions below regarding Section 871(m) and in “United States Federal Tax Considerations—Tax Consequences to Non-U.S. Holders” and “—FATCA” in the accompanying prospectus supplement, if you are a Non-U.S. Holder (as defined in the accompanying prospectus supplement) of the securities, under current law you generally will not be subject to U.S. federal withholding or income tax in respect of any payment on or any amount received on the sale, exchange or retirement of 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. See “United States Federal Tax Considerations—Tax Consequences to Non-U.S. Holders” in the accompanying prospectus supplement for a more detailed discussion of the rules applicable to Non-U.S. Holders of the securities.

As discussed under “United States Federal Tax Considerations—Tax Consequences to Non-U.S. Holders” in the accompanying prospectus 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 Internal Revenue Service (“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 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 prospectus 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 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 $22.25 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 $22.25 for each security they sell.

PS-10

Citigroup Global Markets Holdings Inc.

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.

© 2025 Citigroup Global Markets Inc. All rights reserved. Citi and Citi and Arc Design are trademarks and service marks of Citigroup Inc. or its affiliates and are used and registered throughout the world.

PS-11

FAQ

What is the ticker for Citigroup’s Market-Linked Securities discussed here?

The notes are issued by Citigroup Global Markets Holdings Inc. and guaranteed by Citigroup Inc. (symbol C); they do not trade under an exchange ticker.

How much principal could I lose on these Citigroup notes?

At maturity your loss is capped at $50 per $1,000 note (5 % of principal).

What is the maximum return an investor can earn?

The Maximum Return at Maturity is at least $143 per note (≥ 14.30 %), regardless of higher index gains.

Do these securities pay any interest or dividends?

No. No coupons or dividend pass-through are paid during the life of the notes.

When do the Citigroup market-linked notes mature?

The notes mature on 24-Jun-2027, approximately 23 months after issuance.

Can I sell the notes before maturity?

The notes are not listed; CGMI may provide a secondary market but is under no obligation, so early sale prices could be low.