问题
单项选择题
Will the covariance of returns for two common stocks be negative if the actual returns on both stocks tend to be: Above their expected returns Below their expected returns at the same time at the same time （）
A. No No
B. No Yes
C. Yes No
答案
参考答案：A
解析：
COV( R1, R2)=E[(R1-E(R1))(R2-E(R2))], the covariance of returns for two common stocks tend to be positive if they are above/below their expected returns at the same time.