It’s a trader’s maxim: don’t follow the herd. Now, new research suggests you actually can make money pilling into stocks that speculators are obsessed with, but at a high cost to your nerves. While swimming with the hedge fund sharks returns a few percent more than the market over time, watch out when the rout comes, when crowded shares fall harder than everything else, according to research by three business school professors at the University of North Carolina at Chapel Hill and Wake Forest University.