Which of the following phenomena would be either consistent with or a violation of the efficient market hypothesis? Explain briefly.

a. Money managers that outperform the market (on a risk-adjusted basis) in one year are likely to outperform in the following year.

b. Stock prices tend to be predictably more volatile in January than in other months.

c. Stock prices of companies that announce increased earnings in January tend to outperform the market in February.

d. Stocks that perform well in one week perform poorly in the following week.