There's the standard S&P 500 index (SPX) and the rarer used S&P 500 Total Return index (SPTR). If you compare graphs, you'll find that the latter grows faster. Supposedly, SPTR assumes ...
In the draft chapter about hedge funds of his forthcoming book Andrew Ang postulates the dawn of new factor funds (p. 35 ff.), i.e. funds that directly target factors like volatility, value-growth, ...