(Image source: scmp.com) Shares of Twitter Inc (NYSE:TWTR) are advancing this morning after the microblogging site was upgraded by SunTrust to buy from neutral. According to SunTrust, Twitter is trading at a discount compared to its growth potential. Despite user growth concerns and recent pullbacks in the stock, SunTrust believes that the social media site has a lot positive attributes. For example, the company is experiencing rapid growth in monetization and has potential to increase ad revenue. As a result, the price target was raised to $45 a share. At the current price target level, the suggested upside potential is 41 percent.