A planner is reviewing an equity manager for a client whose investment policy statement requires managers to be judged on return above the return their systematic risk warranted. Over the review period the manager's portfolio returned 12.0 percent, the benchmark market portfolio returned 9.0 percent, the risk free rate was 3.0 percent, and the portfolio's beta measured against that market portfolio was 1.20. Using the Capital Asset Pricing Model to set the required return, what was the manager's Jensen's alpha over the period?
- A3.0 percent, obtained by subtracting the 9.0 percent market portfolio return from the 12.0 percent portfolio return, on the basis that the market return is the return the manager had to beat over the period.
- B9.0 percent, obtained by subtracting the 3.0 percent risk free rate from the 12.0 percent portfolio return, on the basis that alpha measures the reward earned for accepting risk instead of holding the risk free asset.
- C4.8 percent, obtained by multiplying the 6.0 percent market risk premium by the beta of 1.20 to give 7.2 percent, and subtracting that from the 12.0 percent portfolio return without adding the risk free rate back.
- D1.8 percent, obtained by setting the required return at 3.0 percent plus 1.20 times the 6.0 percent market risk premium, giving 10.2 percent, and subtracting that required return from the 12.0 percent portfolio return. Correct
Why A is wrong: Tempting because raw outperformance against the market is the figure most often quoted in a client meeting. It is wrong because it ignores the beta of 1.20, so it gives the manager credit for the extra return that simply came from carrying more systematic risk than the market.
Why B is wrong: Tempting because return above the risk free rate is the numerator of both the Sharpe and the Treynor ratios, so the subtraction is familiar. It is wrong because that quantity is the excess return, and alpha is what remains after the required return for the beta taken is also deducted.
Why C is wrong: Tempting because it applies beta to the market risk premium correctly, which is the step candidates most often miss. It is wrong because the Capital Asset Pricing Model required return is the risk free rate plus that product, and omitting the 3.0 percent understates the hurdle by exactly that amount.
Why D is correct: Correct because Jensen's alpha is the realised return less the Capital Asset Pricing Model required return for the portfolio's beta. The required return is 3.0 plus 1.20 times 6.0, which is 10.2 percent, and 12.0 less 10.2 leaves 1.8 percentage points of return the beta does not explain.