With less than 250 locations, the restaurant chain has plenty of opportunity to expand its footprint.Shares of Sweetgreen (SG 1.63%) increased by more than 33% after the restaurant operator raised its outlook following strong second-quarter results. The stock has now tripled this year.Already one of the hottest stocks on the market, Sweetgreen may seem like a missed opportunity to anyone who was sitting on the sidelines during its post-earnings surge. But let's take a closer look at the company's most recen ...