Stocks are bought on the expectation that they will go up. If a stock is going up in price, it is fulfilling that expectation. When the price is going down, it is denying that expectation. Therefore, it is logical to buy a stock when its price is going up. Moreover, one of the best times to buy a stock is when the price has broken above an old high. At this point there are no unhappy holders who are waiting to dump the stock. If the stock is fairly valued, there should be clear sailing ahead.