Carsten Kengeter, chief executive officer of Deutsche Boerse AG, reacts during an interview in London, U.K., on Friday, May 27, 2016. In its review of the merger between Deutsche Boerse AG and London Stock Exchange Group Plc, the regulator of the Frankfurt bourse will pay close attention to the U.K.s referendum on European Union membership and the location of the future headquarters of the combined company, the economy minister of the German state of Hesse said. Photographer: Simon Dawson/Bloomberg via Getty Images