This filing relates solely to preliminary communications made before the commencement of a tender offer for
the outstanding common stock of Zogenix, Inc. (Zogenix) by Zinc Merger Sub, Inc. (the Purchaser), an indirect wholly owned subsidiary of UCB S.A. (UCB), to be commenced pursuant to the Agreement and Plan of Merger
dated as of January 18, 2022, among Zogenix, Purchaser and UCB.
Important Information About the Tender Offer
The tender offer described in this document has not yet commenced. This document is for informational purposes only and is neither an offer to purchase nor a
solicitation of an offer to sell any shares of the common stock of Zogenix or any other securities, nor is it a substitute for the tender offer materials described herein. At the time the planned tender offer is commenced, a tender offer statement
on Schedule TO, including an offer to purchase, a letter of transmittal and related documents, will be filed by UCB and the Purchaser with the Securities and Exchange Commission (the SEC), and a solicitation/recommendation statement on
Schedule 14D-9 will be filed by Zogenix with the SEC.
INVESTORS AND SECURITY HOLDERS ARE URGED TO READ BOTH
THE TENDER OFFER MATERIALS CAREFULLY (INCLUDING AN OFFER TO PURCHASE, A RELATED LETTER OF TRANSMITTAL AND CERTAIN OTHER TENDER OFFER DOCUMENTS) AND THE SOLICITATION/RECOMMENDATION STATEMENT ON SCHEDULE 14D-9
REGARDING THE OFFER, AS THEY MAY BE AMENDED FROM TIME TO TIME, WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION THAT INVESTORS AND SECURITY HOLDERS SHOULD CONSIDER BEFORE MAKING ANY DECISION REGARDING TENDERING THEIR
SECURITIES.
Investors and security holders may obtain a free copy of the Offer to Purchase, the related Letter of Transmittal, certain other tender
offer documents and the Solicitation/Recommendation Statement (when available) and other documents filed with the SEC at the website maintained by the SEC at www.sec.gov or by directing such requests to the Information Agent for the tender offer,
which will be named in the tender offer statement. In addition, Zogenix files annual, quarterly and current reports and other information with the SEC, which is available to the public from commercial document-retrieval services and at the
SECs website at www.sec.gov. Copies of the documents filed with the SEC by UCB in connection with the tender offer may be obtained at no charge on UCBs internet website at www.ucb.com or by contacting UCB at Allée de la Recherche,
60, 1070 Brussels, or via phone +32 2 559 99 99.
Copies of the documents filed with the SEC by Zogenix may be obtained at no charge on Zogenixs
internet website at www.Zogenix.com or by contacting Zogenix at 5959 Horton Street, Suite 500, Emeryville, California 94608 or (510) 550-8300.
Forward-Looking Statement of UCB S.A.
This document
includes statements that are not statements of historical fact, or forward-looking statements, including with respect to UCBs proposed acquisition of Zogenix. Such forward-looking statements include, but are not limited to, the
ability of UCB and Zogenix to complete the transactions contemplated by the merger agreement, including the parties ability to satisfy the conditions to the consummation of the offer contemplated thereby and the other conditions set forth in
the merger agreement, statements about the expected timetable for completing the transaction, UCBs and Zogenixs beliefs and expectations and statements about the benefits sought to be achieved in the proposed acquisition of Zogenix, the
potential effects of the acquisition on both UCB and Zogenix, the possibility of any termination of the merger agreement, as well as the expected benefits and success of Zogenixs product candidates. These statements are based upon the current
beliefs and expectations of UCBs management and are subject to significant risks and uncertainties. There can be no guarantees that the conditions to the closing of the proposed transaction will be satisfied on the expected timetable or at
all, with respect to pipeline products, that the products will receive the necessary regulatory approvals or that they will prove to be commercially successful. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual
results may differ materially from those set forth in the forward-looking statements.