Insurers including Travelers Cos., Swiss Re AG and Munich Re fell as the U.S. east coast prepared for Hurricane Sandy, which may cost the industry as much as $6.3 billion, according to Kinetic Analysis Corp.

Insurance was the worst-performing industry in the STOXX Europe 600 Index, down 1.6 percent compared with the index's 0.7 percent decline at 11:32 a.m. in London. Munich Re traded 2.1 percent lower at 121.75 euros, Swiss Re fell 2.6 percent and New York-based Travelers dropped 0.9 percent in European trading.

"It is heading for a region with huge population density and a region which has not been hit by a hurricane for a long time," Fabrizio Croce, a Zurich-based insurance analyst at Kepler Capital Markets, wrote in a note to clients today. "Inhabitants have not been able to rebuild new homes recently and therefore incentives to claim for any damage are huge."