After conducting an extensive analysis of past stock prices, you come up with the following observations. Which of your observations would appear to contradict the weak form of the e cient market hypothesis? Explain.

(a) The average rate of return is significantly greater than zero.

(b) One could have made superior returns by buying stocks after a 5% rise in price and sell after a 5% fall.

(c) Insiders earn abnormal trading profits.

(d) The correlation between the market rate of return one week and the rate of return the following week is zero.