This could be an opportunity.Shares of energy drink maker Celsius Holdings (CELH 1.31%) dropped 28.6% in June, according to data provided by S&P Global Market Intelligence. Investors have been fretting over the company's inventory levels and market-share trends, leading to its subpar performance last month.Fears are bubbling up with CelsiusCelsius and its line of energy drinks have been around for years. But only within the last five years or so has the company really started to climb the energy-drink ranki ...