Shares of energy-drink company Celsius Holdings (NASDAQ: CELH) surged 31.3% in May, according to data provided by S&P Global Market Intelligence, and have gone on to hit new all-time highs in June. After the shares gained over 2,800% in just the past five years, many investors are betting on a pullback in the stock price. In the case of Celsius, over 10.4 million shares were sold short as of May 15, according to data from Nasdaq.