Base Prospectus dated 8 March 2021 UCB SA (incorporated with limited liability in Belgium) as Issuer EUR 5,000,000,000 Euro Medium Term Note Programme Due from one month from the date of original issue This base prospectus (the “Base Prospectus”) relating to the EUR 5,000,000,000 Euro Medium Term Note Programme (the “Programme”) of UCB SA, a limited liability company (société anonyme) incorporated under the laws of Belgium, having its registered office at Allée de la Recherche 60, B-1070 Brussels and registered with the Crossroads Bank for Enterprises under number 0403.053.608 (“UCB”, or the “Issuer”) is valid, for the purpose of the admission to trading and listing of the Notes (as defined below) on the regulated market of Euronext Brussels or on another regulated market in the European Economic Area (the “EEA”), for a period of twelve months from the date of approval. Any Notes issued under the Programme are issued subject to the provisions set out herein. Under the Programme, the Issuer, subject to compliance with all relevant laws, regulations and directives, may from time to time issue Euro Medium Term Notes (the “Notes”) as may be agreed between the Issuer and the relevant Dealer (as defined below). The minimum Specified Denomination of Notes shall be EUR 100,000 (or its equivalent in other currencies).The maximum aggregate nominal amount of Notes outstanding will not at any time exceed EUR 5,000,000,000 (or the equivalent in other currencies). This Base Prospectus has been approved as a base prospectus for the purposes of Article 8 of Regulation 2017/1129 (as amended, the “Prospectus Regulation”) on 8 March 2021 by the Belgian Financial Services and Markets Authority (the “FSMA”) in its capacity as competent authority in accordance with Article 20 of the Prospectus Regulation. The FSMA only approves this Base Prospectus as meeting the standards of completeness, comprehensibility and consistency imposed by the Prospectus Regulation. The approval by the FSMA should not be considered as an endorsement of the Issuer or of the quality of the Notes. References in this Base Prospectus to Notes being “listed” (and all related references) shall mean that such Notes have been admitted on Euronext Brussels’ regulated market. The regulated market of Euronext Brussels is a regulated market for the purposes of Directive 2014/65/EU, as amended (“MiFID”). However, unlisted Notes or Notes listed on another market may also be issued pursuant to the Programme. The relevant Final Terms (as defined below) in respect of the issue of any Notes will specify whether or not such Notes will be listed and admitted to trading on the regulated market of Euronext Brussels or on any other stock exchange. The requirement to publish a prospectus under the Prospectus Regulation only applies to Notes which are to be admitted to trading on a regulated market in the EEA and/or offered to the public in the EEA other than in circumstances where an exemption is available under Article 1(4) and/or 3(2) of the Prospectus Regulation. References in this Base Prospectus to “Exempt Notes” are to Notes for which no prospectus is required to be published under the Prospectus Regulation. The FSMA has neither approved nor reviewed information contained in this Base Prospectus in connection with Exempt Notes. Notice of the aggregate nominal amount of Notes, interest (if any) payable in respect of Notes, the issue price of Notes and certain other information which is applicable to each Series (as defined under “Terms and Conditions of the Notes”) of Notes will be set forth in a final terms document (the “Final Terms”) which, with respect to Notes to be listed on the regulated market of Euronext Brussels, will be filed with the FSMA. Copies of Final Terms in relation to Notes to be listed on the regulated market of Euronext Brussels will also be published on the website of Euronext Brussels (www.euronext.com). In the case of Exempt Notes, notice of the aggregate nominal amount of Notes, interest (if any) payable in respect of Notes, the issue price of Notes and certain other information which is applicable to each Tranche will be set out in a pricing supplement document (the “Pricing Supplement”). Any reference in this Base Prospectus to "Final Terms", "relevant Final Terms" or "applicable Final Terms" will be deemed to include a reference to "Pricing Supplement", "relevant Pricing Supplement" or "applicable Pricing Supplement" in relation to Exempt Notes, to the extent applicable. The Notes shall be wholesale non-equity securities in the meaning of the Commission delegated regulation (EU) 2019/980 of 14 March 2019 supplementing the Prospectus Regulation as regards the format, content, scrutiny and approval of the prospectus to be published when securities are offered to the public or admitted to trading on a regulated market, and repealing Commission Regulation (EC) No 809/2004 (hereinafter referred to as “Commission delegated Regulation (EU) 2019/980”). This Base Prospectus has been prepared in accordance with annexes VII and XV of the Commission delegated Regulation (EU) 2019/980. Each Series (as defined in “Overview of the Programme – Method of Issue”) of Notes issued by UCB will be cleared through the clearing system operated by the National Bank of Belgium or any successor thereto (the “Securities Settlement System”). Such Notes will be issued in dematerialised form. Among others, Euroclear Bank SA/NV, as operator of the Euroclear System ("Euroclear"), Clearstream Banking AG, Frankfurt ("Clearstream, Frankfurt"), Monte Titoli S.p.A., Italy ("Monte Titoli"), SIX SIS Ltd., Switzerland ("SIX SIS"), Interbolsa S.A. (“Interbolsa”), Euroclear France SA (“Euroclear France”) and LuxCSD S.A. (“LuxCSD”) maintain accounts in the Securities Settlement System (for a list of all the NBB-SSS participants, please refer to https://www.nbb.be/nl/list-nbb-investor-icsds). The Issuer is not rated. The Programme is unrated. This Base Prospectus is valid for 12 months from its date in relation to Notes which are to be admitted to trading on a regulated market. The obligation to supplement this Base Prospectus in the event of a significant new factor, material mistake or material inaccuracy does not apply when this Base Prospectus is no longer valid. Notes issued under this Programme constitute unsecured debt instruments. By subscribing to the Notes, investors lend money to the Issuer who undertakes to pay interest (if any) and to reimburse the principal amount on the maturity date. In case of bankruptcy or default by the Issuer, investors may not recover the amounts they are entitled to and risk losing all or a part of their investment. Investing in Notes issued under the Programme involves certain risks and may not be a suitable investment for all investors. Each prospective investor must carefully consider whether it is suitable for that investor to invest in the Notes in light of its knowledge and financial experience and should, if required, obtain professional advice. Prospective investors should read the Base Prospectus in its entirety and, in particular, the risk factors described under the section headed "Risk Factors" before making an investment decision in order to fully understand the potential risks and rewards associated with the decision to invest in the Notes. The date of this Base Prospectus is 8 March 2021 in relation to Notes which are to be admitted to trading on a regulated market in the European Economic Area (the “EEA”) and/or offered to the public in the EEA other than in circumstances where an exemption is available under Article 1(4) and/or Article 3(2) of the Prospectus Regulation. This Base Prospectus is valid until and including 8 March 2022 in relation to Notes which are to be admitted to trading on a regulated market. The obligation to publish a supplement to this Base Prospectus in the event of a significant new factor, material mistake or material inaccuracy does not apply when this Base Prospectus is no longer valid”. Arranger BNP PARIBAS Dealers Barclays IMI – Intesa Sanpaolo BBVA KBC Bank BofA Securities Mizuho Securities BNP PARIBAS Santander Corporate & Investment Banking Commerzbank SMBC Nikko Crédit Agricole CIB Wells Fargo Securities ING TABLE OF CONTENTS Page OVERVIEW OF THE PROGRAMME .............................................................................................................. 3 RISK FACTORS .............................................................................................................................................. 10 DOCUMENTS INCORPORATED BY REFERENCE .................................................................................... 39 TERMS AND CONDITIONS OF THE NOTES ............................................................................................. 41 USE OF PROCEEDS ....................................................................................................................................... 77 DESCRIPTION OF UCB ................................................................................................................................. 79 TAXATION .................................................................................................................................................... 107 SUBSCRIPTION AND SALE ........................................................................................................................ 117 FORM OF THE NOTES ...............................................................................................................................