Between the end of 2000 and the end of 2005, assets in U.S. mutual funds swelled from $6.96 trillion to $8.91 trillion, according to data from the Investment Company Institute. Compounded annually, that's growth of a handsome 5.1%, and if the current trend continues, the industry should pass the $11 trillion mark by 2010.
But it's still just one-third of the growth the industry realized between 1982 and 1999, which included one of the greatest bull markets in history. During the 1990s, the industry grew by an astonishing 21%. Some experts believe that exchange-traded funds could slow growth further.