Also, margins and returns are razor thin, way below industry averages. This shows that the company is not optimizing resource use or reinvesting its money in profitable ways. Furthermore, the professional networking giant has limited presence in high-growth markets, where competitors like Viadeo have larger shares. Facebook Inc (NASDAQ : FB) might also pose a real threat someday soon. Finally, security issues have been raised once and again regarding LinkedIn Corp (NYSE : LNKD). You might remember the case of a group of hackers who stole millions of LinkedIn user passwords. So, although there is some upside potential on this stock, risks abound, making its sky high valuation a little bit too high. Disclosure: Javier Hasse holds no position in any stocks mentioned Recommended Reading: What Levi Strauss Can Teach Us About Twitter Google and Facebook to Sign Advertising Truce How LinkedIn Plans to Disrupt the World