For those who don’t spend their working hours in the board rooms of public companies, it’s easy to assume that talking to your biggest shareholders is a major part of a board member’s work.

In reality, the communication channels between institutional investors and boards are informal and unstructured. Sometimes they’re hardly even open to begin with—a factor keenly exploited by activist investors, who pounce on companies that are deaf or unresponsive to investor concerns.

“In many cases the activists are crystallizing a level of discontent they perceive in the market,” says Michelle Edkins, the head of corporate governance at BlackRock Inc., the world’s largest asset manager. “If mainstream investors feel they can communicate their concerns and be heard, then the board may be forewarned and do something before activists get involved.”