A recent BusinessWeek article pointed that six of the ten largest U.S. stock funds have reported correlations of 0.99 with the S&P 500, meaning their moves almost exactly mirror the S&P 500. One investment manager stated that investors have a "risk-on/risk-off" attitude that leads at times to violent swings. The high correlation is making it difficult for actively managed funds to produce better returns than the lower-cost index funds.