花旗集团美股招股说明书(2025-10-23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, underlying supplement, prospectus supplement and prospectus are not an offerto 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 OCTOBER 22, 2025October, 2025 Medium-Term Senior Notes, Series NPricing Supplement No. 2025-USNCH29086Filed Pursuant to Rule 424(b)(2)Registration Statement Nos. 333-270327 and 333-270327-01 Citigroup Global Markets Holdings Upturn Securities Linked to the SPDR®S&P®Regional Banking ETF Due May 5, 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 debtsecurities, the securities do not pay interest and do not repay a fixed amount of principal at maturity. Instead, the securities offer a payment at maturity that may be greater than, equal to orless than the stated principal amount, depending on the performance of the underlying specified below from the initial underlying value to the final underlying value.▪ The securities offer modified exposure to the performance of the underlying, with the opportunity to participate in a limited range of potential appreciation of the underlying at the upsideparticipation rate specified below. In exchange, investors in the securities must be willing to forgo any appreciation of the underlying in excess of the maximum return at maturity specifiedbelow and must be willing to forgo any dividends with respect to the underlying. In addition, investors in the securities must be willing to accept full downside exposure to any depreciationof the underlying. If the final underlying value is less than the initial underlying value, you will lose 1% of the stated principal amount of your securities for every 1% by whichthe final underlying value is less than the initial underlying value. You may lose your entire investment in the securities.▪ In order to obtain the modified exposure to the underlying that the securities provide, investors must be willing to accept (i) an investment that may have limited or no liquidity and (ii) therisk 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 CitigroupGlobal Markets Holdings Inc. and Citigroup Inc. If the underlying depreciates from the initial underlying value to the final underlying value, your payment at maturity will be less, andpossibly significantly less, than the stated principal amount of your securities. You should not invest in the securities unless you arewilling and able to bear the risk of losing a significant portion, and up to all, of your investment. Underlying return:(i) The final underlying valueminusthe initial underlying value,divided by(ii) the initial underlying value (1) Citigroup Global Markets Holdings Inc. currently expects that the estimated value of the securities on the pricing date will be at least $912.50 per security, which will be less than the issue price. Theestimated 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 ofthe 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 $975.00 per security, assuming no custodial fee is charged by a selected dealer, and up to $980.00 persecurity, assuming the maximum custodial fee is charged by a selected dealer. See “Supplemental Plan of Distribution” in this pricing supplement. (3)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 fromexpected hedging activity related to this offering, even if the value of the securities declines. See “Use of Proceeds and Hedging” in the accompanying prospectus. Investing in the securities involves risks not associated with an investment in conventional debt securities. See “Summary Risk Factors” beginning on 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 theaccompanying product supplement, underlying supplement, prospectus supplement and prospectus are truthful or complete. Any representation to the contrary