Some hedge fund managers have in recent weeks posted their worst trading results in almost a year, as many got caught in crowded trades amid highly volatile markets, according to Goldman Sachs. Goldman said in a note dated Wednesday that systematic managers — sometimes called quant funds — have given back a quarter of their year-to-date returns, now up 10.8% for the year, down from a return of 14.4% on June 22. Losses came from bets against U.S. equities, Asian developed-market stocks and, to a lesser extent, Europe. Huge volatility in shares of chipmakers had made for a tricky trading environment in late June and into early July, but hefty levels of leverage among retail investors in Korean markets amplified share-price moves. Quant funds made up roughly 10% of the largest hedge funds in 2025, according to data from S&P Global. Regulators have warned about lofty valuations in the tech sector and voiced concern over how the growing role hedge funds play adds to volatility and risk. Goldman said fundamental managers, or stockpicking funds, were down 2.2% in the same period but still up 15.5% this year, and have "aggressively" fled trades related to AI, bringing hedge fund leverage to its lowest levels of the last year.