NO.PZ2021101401000003
问题如下:
Assume that the following one-factor model describes the expected return for portfolios:
Also assume that all investors agree on the expected returns and factor sensitivity of the three highly diversified Portfolios A, B, and C given in the following table:
Assuming the one-factor model is correct and based on the data provided for Portfolios A, B, and C, determine if an arbitrage opportunity exists and explain how it might be exploited.
(备注:课后题原题,虽然题目形式是问答题,但是建议不用纠结题目形式,了解题目考查角度即可)
选项:
解释:
According to the one-factor model for expected returns, the portfolio should have these expected returns if they are correctly priced in terms of their risk:
Portfolio A
E(RA) = 0.10 + 0.12βA,1 = 0.10 + (0.12)(0.80) = 0.10 + 0.096 = 0.196
Portfolio B
E(RB) = 0.10 + 0.12βB,1 = 0.10 + (0.12)(1.00) = 0.10 + 0.12 = 0.22
Portfolio C
E(RC) = 0.10 + 0.12βC,1 = 0.10 + (0.12)(1.20) = 0.10 + 0.144 = 0.244
In the table below, the column for expected return shows that Portfolios A and C are correctly priced but Portfolio B offers too little expected return for its risk, 0.15 or 15%.
By shorting Portfolio B (selling an overvalued portfolio) and using the proceeds to buy a portfolio 50% invested in A and 50% invested in C with a sensitivity of 1 that matches the sensitivity of B, for each monetary unit shorted (say each euro), an arbitrage profit of €0.22 -€0.15 = €0.07 is earned.
比如这题 Portfolio B 的E(rp)是0.22,市场的E(rp)是0.156,
那么如果去long Portfolio B, 最后获得的收益是0.156还是0.22?