Major Shareholder Announcement

Company Announcement

• Major shareholder announcement for Genmab A/S

Genmab A/S (Copenhagen:GEN) announces under reference to Section 29 of the Danish Securities Trading Act that Johnson & Johnson Development Corporation (JJDC) has informed us that as of October 16, 2012 their ownership in Genmab A/S consists of 5,400,000 shares, which amounts to 10.73% of the total shares in the company. At the same time Hendrikus Hubertus Franciscus Stienstra has informed us that as of October 16, 2012 his ownership in Genmab A/S (partly through Mercurius Beleggingsmaatschappij B.V., Stimex Participatie Maatschappij B.V., De Thermen Beheer B.V. and Mosam Onroerend Goed B.V.) consists of 4,842,268 shares, which in total amounts to 9.63% of the total shares in the company.

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(r)), 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: [phone]; M: [phone]; E: [e-mail]

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(r); the Y-shaped Genmab logo(r); HuMax(r); HuMax-CD20(r); DuoBody(tm) and UniBody(r)are all trademarks of Genmab A/S. Arzerra(r) is a trademark of GlaxoSmithKline.

Company Announcement no. 26 CVR no. 2102 3884 Genmab A/S Bredgade 34E 1260 Copenhagen K Denmark