With Google (GOOGL 0.54%) shares handily outperforming the major averages this year, it certainly begs the question if this recent run is sustainable. According to Larry Kim, the founder and chief technology officer of WordStream, certain areas of display and mobile ads are currently undervalued on the Google network. Fool contributor Steve Heller believes that once advertisers catch wind of this opportunity, it could pave the way for Google shares to continue rallying. Check out the video below to get into the details.