COPENHAGEN - A.P. Moller-Maersk will continue to invest in its shipping unit to retain its leading market share in the industry, which has experienced a prolonged slump, Chief Executive Nils Smedegaard Andersen said on Friday. Andersen referred to Maersk’s decision, announced earlier this week, that it would not take order options on six of its flagship mega-vessels. “There’s absolutely no drama on this—when you take options it’s because you want to be flexible. We will continue to invest to retain out market share,” Andersen told analysts during a conference call.