Arzerra® Third Quarter 2013 Net Sales Figures C

Company Announcement

• Worldwide net sales of Arzerra® in Q3 2013 totaled GBP 17.8 million
• Genmab expects royalty payment of approx. DKK 31 million

Copenhagen, Denmark; October 23, 2013 – Genmab A/S (OMX: GEN) announced today that the Arzerra (ofatumumab) net sales during the third quarter of 2013 were GBP 17.8 million (approximately DKK 155 million). This figure consists of net sales in the US of GBP 13.1 million and in the rest of the world of GBP 4.7 million. Under the terms of the collaboration with GlaxoSmithKline (GSK), Genmab expects to receive a royalty payment of approximately DKK 31 million.

During the first half of 2013, rest of world sales of Arzerra were impacted by sales related to the supply of Arzerra for clinical trials run by other companies. Sales were not positively impacted by clinical trial material sales during the third quarter.

The conversion from GBP to DKK has been made using the Danish Central Bank average rates for the third quarter of 2013 (GBP 1.00 = DKK 8.7287).

About Genmab A/S Genmab is a publicly traded, international biotechnology company specializing in the creation and development of differentiated human antibody therapeutics for the treatment of cancer. Founded in 1999, the company’s first marketed antibody, ofatumumab (Arzerra ^® ), was approved to treat chronic lymphocytic leukemia in patients who are refractory to fludarabine and alemtuzumab after less than eight years in development. Genmab’s validated and next generation antibody technologies are expected to provide a steady stream of future product candidates. Partnering of innovative product candidates and technologies is a key focus of Genmab’s strategy and the company has alliances with top tier pharmaceutical and biotechnology companies. For more information visit www.genmab.com .

Contact: Rachel Curtis Gravesen, Senior Vice President, Investor Relations & Communications T: +45 33 44 77 20; M: +45 25 12 62 60; E: r.gravesen@genmab.com This Company Announcement contains forward looking statements. The words “believe”, “expect”, “anticipate”, “intend” and “plan” and similar expressions identify forward looking statements. Actual results or performance may differ materially from any future results or performance expressed or implied by such statements. The important factors that could cause our actual results or performance to differ materially include, among others, risks associated with pre-clinical and clinical development of products, uncertainties related to the outcome and conduct of clinical trials including unforeseen safety issues, uncertainties related to product manufacturing, the lack of market acceptance of our products, our inability to manage growth, the competitive environment in relation to our business area and markets, our inability to attract and retain suitably qualified personnel, the unenforceability or lack of protection of our patents and proprietary rights, our relationships with affiliated entities, changes and developments in technology which may render our products obsolete, and other factors. For a further discussion of these risks, please refer to the risk management sections in Genmab’s most recent financial reports, which are available on www.genmab.com . Genmab does not undertake any obligation to update or revise forward looking statements in this Company Announcement nor to confirm such statements in relation to actual results, unless required by law. Genmab A/S and its subsidiaries own the following trademarks: Genmab ^® ; the Y-shaped Genmab logo ^® ; Genmab in combination with the Y-shaped Genmab logo ^TM ; the DuoBody™ logo; HuMax ^® ; HuMax-CD20 ^® ; DuoBody ^® , HexaBody ^TM and UniBody ^® . Arzerra ^® is a registered trademark of GlaxoSmithKline.   

Company Announcement no. 45 CVR no. 2102 3884

Genmab A/S Bredgade 34E 1260 Copenhagen K Denmark