Distinguish between the following: 'Semi-strong form' and 'Strong form' of efficient market hypothesis.

The efficient-market theory is considered as having three forms, viz. Weak Form, Semi-strong Form and the Strong Form. Semi-strong Form Theory : This form says that the current share valuation is a reflection of historical information plus publicly available knowledge about the company. It maintains that as soon as the information becomes publicly available, it is absorbed and reflected in current prices. An analyst and an investor are similarly placed in so far as making use of the information is concerned. Thus an analyst cannot obtain better returns than an ordinary investor. Strong Form Theory : According to this form, not only is the publicly available information useless to the analyst or the investor, but all information is useless. No information, whether public or inside information can be used to earn better returns than the market.