Assuming 30 trading days horizon, S&P 500 is expected to under-perform the Ford. But the index apears to be less risky and, when comparing its historical volatility, S&P 500 is 1.86 times less risky than Ford. The index trades about -0.05 of its potential returns per unit of risk. The Ford Motor Co is currently generating about 0.13 of returns per unit of risk over similar time horizon. If you would invest  1,495  in Ford Motor Co on May 20, 2013 and sell it today you would earn a total of  70.00  from holding Ford Motor Co or generate 4.68% return on investment over 30 days.