Profits in the stock market can usually be made faster by selling stocks short than by buying them. The reason is that price declines are usually much steeper than price rises, which occur more gradually, over a longer period of time, and are usually accompanied by a healthy amount of pessimism that gradually lessens the longer the price rise continues. Price declines, on the other hand, contain an element of panic that increases as stock prices plunge lower.
Source: Superperformance Stocks by Richard Love
