Argenx Announces Closing of U.S. Public Offering for Gross Proceeds of Approximately $26M

Breda, the Netherlands / Ghent, Belgium - Argenx (Euronext & Nasdaq: ARGX) a clinical-stage biotechnology company developing a deep pipeline of differentiated antibody-based therapies for the treatment of severe autoimmune diseases and cancer, announced today the closing of its public offering in the United States of 5,106,000 American Depositary Shares (ADSs), at a price of $52.00 per ADS, for gross proceeds of approximately $266 million. This includes the full exercise of the underwriters' option to purchase additional ADSs.

Each of the ADSs offered represents the right to receive one ordinary share, nominal value of €0.10 per share.

argenx's ADSs are currently listed on the Nasdaq Global Select Market under the symbol "ARGX," and argenx's ordinary shares are currently listed on Euronext Brussels.

Cowen and Piper Jaffray & Co. acted as joint bookrunning managers for the Offering, and JMP Securities and Wedbush PacGrow acted as co-managers. Kempen & Co was argenx's advisor in connection with the Offering.

A registration statement relating to these securities was declared effective by the U.S. Securities and Exchange Commission (SEC) on December 13, 2017. This registration statement can be accessed through the SEC's website at www.sec.gov.

Copies of the final prospectus for this Offering may be obtained for free from Cowen and Company, LLC, c/o Broadridge Financial Services, 1155 Long Island Avenue, Edgewood, NY 11717, Attn: Prospectus Department, by telephone at (631) 274-2806 or by fax at (631) 254-7140 or from Piper Jaffray & Co., Attn: Prospectus Department, 800 Nicollet Mall, J12S03, Minneapolis, MN 55403, or by telephone at (800)747-3924, or by email at prospectus@pjc.com.

In addition, argenx announced today the listing of and the commencement of dealings in its 5,106,000 new ordinary shares underlying the ADSs (the New Ordinary Shares) on the regulated market of Euronext Brussels, effective today, following Euronext Brussels' approval of argenx's request for the admission to listing and trading of the New Ordinary Shares on the regulated market of Euronext Brussels.

This press release is for information purposes only and does not constitute, and should not be construed as, an offer to sell or the solicitation of an offer to buy or subscribe to any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale is not permitted or to any person or entity to whom it is unlawful to make such offer, solicitation or sale. Reference is also made to the restrictions set out in "Important information" below. This press release is not for publication or distribution, directly or indirectly, in or into any state or jurisdiction into which doing so would be unlawful or where a prior registration or approval is required for such purpose.

About argenx
argenx is a clinical-stage biotechnology company developing a deep pipeline of differentiated antibody-based therapies for the treatment of severe autoimmune diseases and cancer. We are focused on developing product candidates with the potential to be either first-in-class against novel targets or best-in-class against known, but complex, targets in order to treat diseases with a significant unmet medical need. Our ability to execute on this focus is enabled by our suite of differentiated technologies. Our SIMPLE Antibody(TM) Platform, based on the powerful llama immune system, allows us to exploit novel and complex targets, and our three antibody engineering technologies are designed to enable us to expand the therapeutic index of our product candidates.