Bullish investors profit from buying stocks at a low price and selling them for a higher price. Investors may also make money when they are bearish and believe the stock market or a particular share will decline in value in the future. Investors who short shares of a stock never own the stock, but borrow the shares for a specific time period. Shorting shares of a stock requires an understanding of how to value stocks and trade on margin. Shorting a stock can lead to substantial profits for experienced investors, but it can lead to substantial losses for investors who lack sufficient knowledge and experience.