The profits generated by Ray Dalio’s Bridgewater Associates and Jim Simons’ Renaissance Technologies “beat their rivals in a tough year for hedge funds in 2018, making a combined $13 billion for their investors.” This according to a recent article in Bloomberg.

“The profits accounted for more than half the money generated by the top 20 managers last year,” the article reported (based on estimates by LCH Investments NV, a fund of hedge funds). Rick Sopher, Chairman of LCH, explained: “Most managers in the top 20 either managed to stay out of trouble when equity markets fell sharply toward year-end, or had an investment approach that was not linked to the direction of equity markets.”

The article notes that both Bridgewater and Renaissance are “well-diversified funds that can benefit from rising and falling stocks.” It adds that last year the hedge fund industry as a whole suffered its worst performance since 2011, with several big names leaving the market entirely.

“Six in ten hedge funds lost money,” the article states, “the highest proportion since the financial crisis, as a sharp spurt in volatility made it tougher to make profitable bets.”