Private equity has delivered superior returns to investors over the past two decades. Research by Professor Steven Kaplan of the University of Chicago, has shown that over the last 20 years the top buyout funds usually generate returns more than triple the overall returns of the US stock market. Source

Another study found that during the past 25 years, top-quartile PE funds generated annual returns of nearly 39 percent, compared to 12.1 percent for the S&P 500 and 12.3 percent for the NASDAQ. By 2008, the total net profits distributed to investors worldwide by private equity funds raised through 2007 were $1.12 trillion. See Insight - Why Should You Invest in Private Equity?