The most activist investors tend to be union and public pension funds. I worry that their interests may depart from those of other investors, which is the subject of a very good article in today's LA Times($):
"I don't want my board of directors worrying about whether they're going to have problems with the union pension fund if they drive a hard bargain at the bargaining table," said Stephen M. Bainbridge, a professor at the UCLA School of Law.
Joseph A. Grundfest, a professor at Stanford and a former SEC commissioner, called it "fair and appropriate" to consider the pressures and motivations that influence the giant pension funds in their dealings with companies — just as the public has long scrutinized the conflicts of corporate executives. "What's good for the goose is good for the gander," he said. "There are potential conflicts on both sides of this fence." ...
"You don't run General Motors like a New England town meeting," Bainbridge said. "You can't have millions of shareholders weighing in on every decision that the board makes."
Well, you can see why I thought it was so good, but it really is pretty thoughtful (especially by the Times' standards!).