花旗集团美股招股说明书(2025-10-28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 27, 2025October, 2025 Medium-Term Senior Notes, Series NPricing Supplement No. 2025-USNCH29152Filed Pursuant to Rule 424(b)(2)Registration Statement Nos. 333-270327 and 333-270327-01 Citigroup Global Markets Holdings Autocallable Securities Linked to the S&P 500®Index Due November 3, 2028▪ 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, do not guarantee the repayment of principal at maturity and are subject to potential automatic early redemption on a periodic basis on theterms described below. Your return on the securities will depend on the performance of the underlying specified below.▪ The securities offer the potential for automatic early redemption at a premium following the first valuation date (other than the final valuation date) on which the closing value of theunderlying is greater than or equal to the initial underlying value. If the securities are not automatically redeemed prior to maturity, the securities will provide for (i) repayment of the statedprincipal amountplusa premium at maturity if the final underlying value is greater than or equal to the initial underlying value or (ii) repayment of the stated principal amount at maturity,with no premium, if the final underlying value is less than the initial underlying value but greater than or equal to the final barrier value specified below.However, if the securities are notautomatically redeemed prior to maturity and the final underlying value is less than the final barrier value, you will lose 1% of the stated principal amount of your securities forevery 1% by which the final underlying value is less than the initial underlying value.Although you will have downside exposure to the underlying, you will not receive dividends withrespect 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 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. November 9, 2026, November 1, 2027 and October 31, 2028 (the “final valuation date”), each subject to postponement if suchdate is not a scheduled trading day or certain market disruption events occur Automatic earlyredemption:If, on any valuation date prior to the final valuation date, the closing value of the underlying is greater than or equal to the initialunderlying value, the securities will be automatically redeemed on the third business day immediately following that valuationdate for an amount in cash per security equal to $1,000 plus the premium applicable to that valuation date. If the securities areautomatically redeemed following any valuation date prior to the final valuation date, they will cease to be outstanding and youwill not receive the premium applicable to any later valuation date. The premium applicable to each valuation date is the percentage of the stated principal amount indicated below.The premiummay be significantly less than the appreciation of the underlying from the pricing date to the applicable valuation date. •November 9, 2026:8.30% of the stated principal amount •November 1, 2027:16.60% of the stated principal amount•October 31, 2028:24.90% of the stated principal amount Payment at maturity:If the securities are not automatically redeemed prior to maturity, you will receive at maturity for each security you then hold:■ If the final underlying value isgreater than or equal tothe initial underlying value:$1,000 + the premium applicable to the final valuation date■If the final underlying value isless thanthe initial underlying value butgreater 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, at maturity. (1) Citigroup Global Markets Holdings Inc. currently expects that the estimated value of the s