Sterne Agee has upgraded Groupon (GRPN 0.57%) to a buy, and has given the stock a $9 price target. In this video, however, Motley Fool senior technology analyst Eric Bleeker gives investors a word of caution. He notes that while the company is aiming to expand beyond being an email-based business to becoming a local marketplace portal with longer-term fixed deals, success in the marketplace arena can be a lot easier said than done and offers little to appeal to consumers who weren't already on the company's e-mails. While investors might be excited by Groupon experimenting with new avenues for growth, jumping in now before we've seen whether a marketplace idea can get traction might be premature.