Northern Trust Asset Management’s largest clients including sovereign wealth funds are separating their U.K. assets from their European and global portfolios as they await the outcome of Brexit. About 30 percent to 40 percent of the mainly institutional clients that invest with the $1 trillion asset manager have asked to segregate their U.K. holdings to manage the risks associated with the talks to leave the European Union, said Wayne Bowers, chief executive officer for Europe and Asia. Northern Trust’s most “sophisticated” clients are doing this to be more “tactical,” he said. “They want to ring-fence their U.K. exposure,” Bowers said at...