It's been a September to remember for Facebook (FB), with shares up 25% so far this month. The social media kingpin is hoping the worst is behind them after going down as the worst U.S. IPO in history. Keep in mind that despite the September bounce, shares are down 40% from the May 18 IPO where they debuted at $38 apiece.

"I think we're heading into a period where these guys are going to pump this thing up ahead of the lockup expirations in October and November," says Eric Jackson, founder of Ironfire Capital. "There's a big flood of stock coming on the market."

Think "tsunami." That's how many FB shares will hit the market by year-end.

The first lockup period, open to some insiders, expired on August 16, bringing 271 million shares to market. Nearly two billion more shares could hit the market in a series of lockups expiring over the next eight months, with none more significant than the two this Fall. Here's a schedule recently published by TheStreet:

Ahead of the expiration dates, Jackson says to expect a string of positive news generated about the company. He says little details about user experience and effective ads could "leak" out, and large shareholders and managers could become a little more visible. "I think they got some religion," he says. "When you get your stock chainsawed in half, it starts to shake the chairs up there."

Notably, Peter Thiel was one of the first board members to sell some of his FB shares at the time of the IPO and after the August lockup expiration. Shortly after, CEO Mark Zuckerberg announced he wouldn't sell his shares for at least a year and then made his first public appearance since the IPO at the TechCrunch conference on September 11. Facebook shares rallied 8% in reaction to Zuck's appearance, where he addressed key issues including the "disappointing" stock performance, mobile strategy, and betting too much on HTML5.

"I'm not a fan of Facebook, but I'm definitely not one of these people who says 'fire Zuckerberg.' He's Facebook; love him or leave him," says Jackson.

Regardless, he believes after the expirations, Facebook shares easily fall below $10. "We saw some ComScore data a few weeks ago that was showing people are pulling back, definitely from the PC side of the business. Even in mobile, they seem to be losing their footing."

Monetizing mobile ads remains the biggest question mark. Jackson believes they should move on to other means of generating revenue, including search. But until then, this month's pop has no staying power in his opinion.

"Ahead of this lockup, I think it gets into the high $20s, but if we're talking 12 months from now, I think mid-teens," he predicts. "And it might go lower than that first."

Please answer our poll question below: Do you think Facebook (FB) will end this year above or below its IPO price of $38 a share?