A widespread investor campaign has made proxy access the “defining governance topic of 2015,” according to a new analysis from Ernst & Young’s EY Center for Board Matters.

Ann Yerger, the center’s executive director, discussed this year’s proxy season in an article on the Harvard Law School Forum on Corporate Governance and Financial Regulation. Some 100 high-profile companies faced proxy access shareholder proposals so far this year, more than four times the number for all of 2014, Yerger said.