The 2017 Tech 40: Peter Brown & Robert Mercer

Last fall a Bloomberg story calling hedge fund firm Renaissance Technologies "the blackest box in all of finance" quoted MIT Sloan School of Management finance professor Andrew Lo as saying the firm is "the commercial version of the Manhattan Project." Lo also said the 300-employee, $48 billion firm is "the pinnacle of quant investing." Both descriptions are apt.

Founded in 1982 by mathematician and former intelligence-community codebreaker James Simons, Renaissance rose to fame despite its unstinting secrecy thanks to the outsize returns of its Medallion Fund, long closed to outside investors. The fund generated annualized returns of nearly 80 percent, before fees, from its inception in 1988 through late 2016, according to Bloomberg. Simons retired in 2009 but remains non-executive chair; today the firm is run by co-CEOs Peter Brown and Robert Mercer, whom Simons recruited in the 1990s out of IBM's Thomas J. Watson Research Center. Both Brown, 62, and Mercer, 71, maintain low profiles, though Mercer's has risen in recent years, particularly after he emerged as an active supporter of Donald Trump's 2016 presidential campaign.

In a rare public appearance in 2014, Mercer, accepting an award, described himself as "simply a computer programmer." He added that in nearly 50 years of coding, he has "taken great pleasure in writing programs that do remarkable things."