Sam bought shares of stock ZYX on 12/31/2014. He uses the CAPM and estimates that the risk-free rate is 3%, the market risk premium is 8% and the CAPM beta for stock ZYX is 1.2. In the year 2015, the return for stock ZYX was -5% and the return for the market portfolio was also -5%. Would you say that Sam demonstrated positive skill, negative skill, or no skill, in choosing to buy ZYX? Why?