To most of us, the Standard & Poor's 500 Index is a monolith, a barometer of our economic health, along with the Dow Jones Average, which has its own larger than life status.  But, thanks to the staff at S&P, we're now able to peel back the curtain on this venerable weathervane and reveal the genies behind it.  No smoke-no mirrors, just all in day's work.

How Many Stocks in the S & P 500?