REG-Major Shareholder Announcement

Company Announcement * Major shareholder announcement for Genmab A/S COPENHAGEN, Denmark; October 2, 2026 – Genmab A/S (Nasdaq: GMAB) announces under reference to Section 30 of the Danish Capital Markets Act that Darwin Global Management Limited (“Darwin”) has informed us that, as of September 28, 2026, Darwin through shares and ADRs held by certain investment funds and portfolios for which Darwin acts as investment manager, controls the voting rights attached to 3,188,361 shares in Genmab A/S, corresponding to 5.11% of the voting rights in Genmab A/S.

About Genmab Genmab is an international biotechnology company dedicated to improving the lives of people with cancer and other serious diseases through innovative antibody medicines. For over 25 years, its passionate, innovative and collaborative team has advanced a broad range of antibody-based therapeutic formats, including bispecific antibodies, antibody–drug conjugates (ADCs), immune-modulating antibodies and other next-generation modalities. Genmab’s science powers eight approved antibody medicines, and the company is advancing a strong late-stage clinical pipeline, including wholly owned programs, with the goal of delivering transformative medicines to patients.