Facebook (META 1.54%) and LinkedIn (LNKD.DL) are now at all-time highs, despite all the skepticism both have garnered over the past few years. Social networking isn't necessarily a zero-sum game, though, and there can be multiple winners. 

However, LinkedIn may face different challenges with international expansion, as its core recruiting business may not be as successful in other countries as it is stateside. Trading at such incredibly high valuation multiples means LinkedIn will inevitably be susceptible to volatility and investors should expect plenty of risk.

In the following video, Erin Kennedy discusses social-media players with Evan Niu, CFA, and Eric Bleeker, CFA.