Whenever you sell a stock, thinking it will go down, somebody else has to buy it, thinking it will go up. One of you is wrong – every time. That’s why you always have to think about, if and why you are on the right side of the trade. An that is why you have to start with a systematic search strategy and not with coincidence.
Bruce C. Greenwald – American professor for finance and asset managemant (*1946), Quotations book 2007