Or do investors just need to be patient? : Activist investor Bill Ackman, who runs Pershing Square Holdings (LSE: PSH), has a large stake in Lowe's (NYSE: LOW). Along with fellow activist investor D.E. Shaw, Ackman shook up company management last year when he installed ex-J.C. Penney CEO Marvin Ellison at the helm, with the goal of improving operating metrics against better-performing rival Home Depot. Ellison took over at the home-improvement giant last July, but apparently, things are off to a rockier-than-anticipated start.