THE BACKGROUND: Energy drinks have been surging in popularity in recent years, particularly among younger consumers. Their growing popularity has also raised concerns about the caffeine levels in the drinks. They can have more than three times as much caffeine than soda such as Coca-Cola or Pepsi.
THE IMPACT: Monster said that it doesn't know what impact, if any, the investigation could have on its business. Its shares were down 11 percent at $54.20 Friday.