What is the difference between RWH and EMH?
In efficient market, the price will be fully reflected by available information.
If there is no news, the price would be unchanged. If there is a news, the price would immediately adjust to a new price reflecting the price. This is the same as the idea of RWH.
However, it is not necessary for efficient efficient market to have random walk prices. I do not totally understand the difference between two hypothesis.
Also, when will the stock prices follow martingale property in efficient market? Only in risk-neutrality?
Which one is the better model for EMH?