Robert Mercer, a billionaire investor and top financial backer of conservative causes, is stepping down as co-chief executive of Renaissance Technologies, as the giant hedge fund faces a backlash from some clients who resent Mr. Mercer’s embrace of polarizing political figures.

Discomfort with Mr. Mercer’s political activism — including protests aimed at university endowments, foundations and pension funds with money invested in Renaissance — has showed signs of taking a small but growing toll. The retirement fund for Baltimore’s police and firefighters, for example, last week asked that all of the $33 million it had invested in Renaissance be refunded, said David A. Randall, the retirement fund’s deputy executive director.



The Baltimore fund had been contacted by a local reporter about whether the pension was bothered by Mr. Mercer’s political activities. Seeking to avoid bad publicity, the pension’s directors convened an emergency conference call and decided to pull their money.

That $33 million withdrawal was a rounding error for Renaissance, which has more than $50 billion in assets. But it signaled a growing unease, inside and outside the firm, about Mr. Mercer’s backing of Stephen K. Bannon, the former White House adviser. Renaissance’s founder, James Simons, is a prominent Democratic booster who supported Hillary Clinton’s presidential campaign.