DUBLIN – To no one's great surprise, the underwriters of Genmab A/S's IPO on Nasdaq exercised their overallotment option, the company announced Friday, taking the total gross to $581.8 million. The Copenhagen-based antibody developer priced the offering of about 32.8 million American depositary shares at $17.75 Thursday. The stock (NASDAQ:GMAB) ended the week at $18.10.