The past decade has seen an explosion in one particular type of investor: the activist shareholder. These are powerful hedge fund managers who make a lot of noise in corporate boardrooms. To some, they’re the squeaky wheels of Wall Street. “They can threaten to take over the company,” said Adam Zurofsky, a corporate attorney who teaches at the Fordham University School of Law. “They can threaten to maybe throw out the directors and officers. Hostile takeovers. And because of that pressure, a lot of managers and directors feel they’re better off following the advice or interests of those investors.” These investors, like any other, want to maximize returns. Sometimes they break up companies to do it.