“No one can consistently predict either the direction of the stock market or the relative attractiveness of individual stocks and thus no one can consistently obtain better overall returns than the market. And while there are undoubtedly profitable trading opportunities that occasionally appear, these are quickly wiped out once they become known. No one person or institution has yet to produce a long-term, consistent record of finding money-making, risk adjusted individual stock trading opportunities, particularly if they pay taxes and incur transaction costs” (A Random Walk Down Walk Street, p.245, Burton G. Malkiel).

What are the weaknesses of this argument?