arGEN-X Raises Additional €1.8 million via Exercise of Over-allotment Option and Announces the End of the Stabilization Period

August 11, 2014

Breda, the Netherlands / Ghent, Belgium – arGEN-X N.V. (“arGEN-X”, Euronext Brussels: ARGX), a clinical-stage biopharmaceutical company focused on creating and developing differentiated therapeutic antibodies for the treatment of cancer and severe autoimmune diseases, announces today the partial exercise of the over-allotment option by KBC Securities (the “Stabilization Manager”) acting on behalf of KBC Securities and Kempen & Co (the “Joint Global Coordinators”) and Petercam (the “Co-Lead-Manager”); and the end of the stabilization period, in relation to its Initial Public Offering that ended on 8 July 2014 (the “IPO”).