It’s no secret that activist hedge funds may not represent the interests of a company’s shareholder base. But a report from Institutional Shareholder Services shows that they don’t look like them, either.

Activists have won numerous seats on corporate boards in recent years as part of efforts to shake up strategy and management teams, or improve profitability. The shareholder advisory firm, however, found that activism eroded board diversity. In fact, a company on the S&P 1500 that was targeted by activist investors between 2011 to 2015 was less likely to have a minority or a woman director after a campaign than before.

But it wasn’t just race and gender that were different for dissident directors nominated by activists. Activists did tend to appoint younger and more independent directors, resulting in boards with a younger average age and more independent members after a challenge.

The backgrounds of their nominees were also significantly different. Dissident directors were three times as likely to be a financial services professional than board-appointed directors were. Conversely, board appointees were twice as likely to be executives as dissident directors were.

Before agreeing to seat new board members, companies and hedge fund activists alike might need to take an honest look at how the changes will impact the diversity of background and experience on the board.