Tough times continue for Facebook. Lock-up periods on shares are approaching expiration, with up to 1.5 billion shares expected to come online before November. This flood of shares coming out of lock-up could drive the share price down even further.

Mark Zuckerberg has said that he will hold his own shares of the company for a year, an announcement likely intended to inspire investor confidence, but it begs the question: Shouldn't it be expected that the CEO of Facebook will maintain his holdings anyway?

Long-term investors should hold off on this IPO until it comes down in price. analysts would also like to see more certainty in Facebook's ad-based revenue model before considering the stock a buy.

Given Facebook's dramatic fall since its IPO in May, most investors don't even want to think about the stock. But there's a lot more to this company than meets the eye -- things every investor should know -- and we've outlined them all in our newest premium research report. So read up on whether there's anything left to "like" about Facebook, and we'll tell you if and when we think it deserves a place in your portfolio. Access your report by clicking here