It is well documented that actively managed stock mutual funds underperform the market. A new study documents that members of the general public who use actively managed mutual funds perform even worse than the funds themselves. Dalbar, a financial research firm in Boston, has studied individual investor and market returns for the last thirty years. Their research showed that for that period, the S&P 500 stock index had an 11.1% annualized return. During that same period, investors in act...