花旗集团美股招股说明书(2025-12-09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 DECEMBER 8, 2025 December, 2025Medium-Term Senior Notes, Series NPricing Supplement No. 2025-USNCH[ ]Filed 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 Futures 40% Edge Volatility 6% Decrement Index (USD) ER Due December 20, 2030 ▪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 the termsdescribed 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 autocall barrier 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 autocall barrier value or (ii) repayment of the stated principal amount at maturity, withno premium, if the final underlying value is less than the autocall barrier 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.▪ The underlying is highly risky because it may reflect highly leveraged exposure to any decline in the S&P 500 Futures Excess Return Index. The S&P 500 Futures ExcessReturn Index tracks futures contracts on the S&P 500®Index and is likely to underperform the S&P 500®Index because of an implicit financing cost. In addition, the underlyingis subject to a decrement of 6% per annum, which will be a significant drag on its performance. You should carefully review the section “Summary Risk Factors—Risksrelating to the S&P 500 Futures 40% Edge Volatility 6% Decrement Index (USD) ER” in this pricing supplement.▪ 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. 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 autocall barrier value:$1,000 + the premium applicable to the final valuation date■If the final underlying value isless thanthe autocall barrier 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) (1) Citigroup Global Markets Holdings Inc. currently expects that the estimated value of the securities on the pricing date will be at least $850.00 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) CGMI will receive an underwriting fee of up to $8.00 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 underwritingfee. For more information on the distribution of the securities, see “Supplemental Plan of Distribution” in th