花旗集团美股招股说明书(2025-09-12版)

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 andExchange 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 SEPTEMBER 12, 2025September, 2025 Medium-Term Senior Notes, Series NPricing Supplement No. 2025-USNCH28329Filed Pursuant to Rule 424(b)(2)Registration Statement Nos. 333-270327 and 333-270327-01 Citigroup Global Markets Holdings Autocallable Equity Linked Securities Linked to NVIDIA Corporation Due September 19, 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 offerperiodic 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 mustbe 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 thefinal 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 riskswill 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 underlyingor 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 andCitigroup 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. On each coupon payment date, unless previously redeemed, the securities will pay a coupon equal to 1.90% of the statedprincipal amount of the securities (equivalent to a coupon rate of 7.60% per annum). If the securities are not automatically redeemed prior to maturity, you will receive at maturity for each security you then hold (inaddition to the final coupon payment):■If the final underlying value isgreater than or equal tothe final barrier value: $1,000■If the final underlying value isless thanthe 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 finalbarrier value, you will receive significantly less than the stated principal amount of your securities, and possiblynothing (other than the final coupon payment), at maturity. (1) Citigroup Global Markets Holdings Inc. currently expects that the estimated value of the securities on the pricing date will be at least $938.00 per security, which will be less than theissue 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 ouraffiliates, 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 theSecurities” in this pricing supplement. (2) 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 affiliatesmay profit from expected hedging activity related to this offering, even if the value of the securities declines. See “Use of Proceeds and Hedging” in the accompanying prospectus. Investing in the securities involves risks not associated with an investment in conventional debt securities. See “Summary Risk Factors” beginning onpage PS-5. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities or determined that this pricingsupplement and the accompanying product supplement, prospectus supplement and prospectus are truthful or complete. Any representation to the contrary is a criminaloffense. You should read this pricing supplement together with the accompanying product supplement, prospectus supplement and prospectus, which can be accessed via thehyperlinks below: 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 theyobligations of, or guaranteed by, a bank. KEY TERMS (continued) If, on any potential autocall date, the closing value of the underlying