James Surowiecki writes in the New Yorker:
Business professors once talked about “the imperial C.E.O.,” but, increasingly, we’re in the era of what Marcel Kahan, a law professor at N.Y.U., calls “the embattled C.E.O.” He told me, “Big shareholders and boards of directors have more power, and are more willing to use it. And C.E.O.s have been the net losers.” The breakdown of the old order began more than thirty years ago, but things have accelerated since the turn of the century. The Sarbanes-Oxley Act, passed in 2002, required greater disclosure to investors, and increased the independence of corporate boards. “In the old days, boards were often loyal to the C.E.O.,” Charles Elson, a corporate-governance expert at the University of Delaware, told me. “Today, they’re more loyal to the company.” The rise of activist investors—who campaign aggressively for change when they’re not satisfied with performance—has exacerbated the trend. One study found that when activist investors succeed in winning seats on the board of directors the probability that the C.E.O. will be gone within a year doubles.