The action expected from the Securities and Exchange Commission on Wednesday will allow groups that own at least 3 percent of a company's stock to put their nominees for board seats on the annual proxy ballot sent to all shareholders.
SEC Chairman Mary Schapiro says the change is "a matter of fairness and accountability."
But the U.S. Chamber of Commerce's president called it "a giant step backwards for average investors" and said the organization will fight it "using every method available."