Portfolio A returned 5.86% p.a. over the evaluation period compared to a 2.57% p.a. for the S&P 500. This equates to a difference or outperformance of 3.29% p.a. According to the CAPM, the annualized alpha of portfolio A is 3.32% p.a. Explain the difference between the two numbers. (Note: It's not due to rounding)