21 4 points On January 1, an investor buys 100 shares of stock in Twitter at the share price of $45. At the time of purchase, the investor estimated the required return for Twitter using the CAPM using a beta of 2.5, a market risk premium of 7.5%, and a risk-free rate of 1.25%. Exactly one year after purchase, the investor sells the shares for $54 per share. Twitter did not pay any dividends over the year. The investor's investment in Twitter generated: a negative alpha an alpha equal to zero. a positive alpha