While shareholder activists are helping corporate boards become younger and more independent, they also are having a negative impact on boards’ gender and racial diversity, according to new research.

Proxy advisory firm Institutional Shareholder Services Inc. (ISS) released a report today that examines the crop of new directors who joined the boards of S&P 1500 companies between 2011 and 2014 as a result of activist campaigns.

The research, which was commissioned by the Investor Responsibility Research Center Institute (IRRCi), found that shareholder activism produces directors who are generally younger and more independent than their predecessors, yet the boards are also less diverse along gender, racial and ethnic lines.

The average age of directors at companies targeted by activists decreased to 59.6 years from 62.2 years, and average tenure decreased to 6.1 years from 9.5 years.

The study also found that activism boosts boardroom independence, as the proportion of independent board members rose to 83% from 79.5% before an activist campaign.

Regarding diversity, the research found that the proportion of boards with at least one female director decreased to 82.8% from 87.1%, which runs counter to the overall trend of increased gender diversity among S&P 1500 companies. Similarly, the share of companies with at least one racial-minority director decreased to 51.6% from 55.9% — also contrary to the overall trend.

“The new report closes that gap with the first deep dive on the implications of dissident campaigns on corporate boards,” said Jon Lukomnik, executive director of IRRCi. “What we’ve found is a bit of a mixed bag. There is more financial expertise and independence, but also less diversity.”