If you were fortunate enough to buy the S&P 500 at the very bottom in October 2002, your investment would be up 68%. Unfortunately but most likely, 99% of investors didn't buy at the bottom. Instead, investors probably worked their way into long positions in 2003 and 2004 once the market proved it could sustain a clear up trend. Below we highlight the returns of an investment in the S&P 500 if you bought at the start of each year and held until now. As shown, unless you bought at the start of 2003, you'd have gains of less than 20% in all instances. And buying at the start of 2007 and 2008 would have resulted in negative returns.