Given investment horizon of 30 days, Alexion Pharmaceuticals Inc is expected to under-perform the Regeneron. But the stock apears to be less risky and, when comparing its historical volatility, Alexion Pharmaceuticals Inc is 1.57 times less risky than Regeneron. The stock trades about -0.18 of its potential returns per unit of risk. The Regeneron Pharmaceuticals Inc is currently generating about -0.11 of returns per unit of risk over similar time horizon. If you would invest  25,996  in Regeneron Pharmaceuticals Inc on May 20, 2013 and sell it today you would lose (1,720) from holding Regeneron Pharmaceuticals Inc or give up 6.62% of portfolio value over 30 days.