Facebook is a hot property, in case you haven’t noticed. Rumors of an IPO have run rampant for three years, but still there’s no news on that front. Meanwhile, Facebook is trying to clamp down on secondary sales of its privately-held stock—especially by employees, according to the Wall Street Journal.

Last week, Facebook announced a new employee stock policy:

The policy says employees who sell their shares could face disciplinary action or be fired, one of these people said. The new rule also leaves room for the company to open a trading window during which employees would be allowed to sell shares in the future.

Facebook spokesman Larry Yu said the company implemented the “insider trading policy to better comply with insider trading laws and to protect the interests of the company and its employees and shareholders.”

Not many of Facebook’s 1200 employees actually own stock options or shares—the WSJ says that many actually hold restricted stock units, which “don’t convert into stock until the company goes public, giving those employees no holdings to trade at this time.”

Naturally, Facebook probably wants to keep the major interests and stockholders close. But Facebook also dislikes the secondary market sales because they allow individuals to influence the overall value of the company. However, they’re obviously not always averse to employees selling stock. Last year, Facebook garnered $200M from Russian company Digital Sky Technologies partially by allowing employees to sell portions of their stock.

However, that may not be the only reason. As the WSJ says,

Adam Oliveri, managing director of SecondMarket’s private company market, . . . says that he thinks Facebook’s purported goal of trying to combat insider trading is a “chimera” for it trying to stay under the 500 shareholder threshold at which the Securities and Exchange Commission requires companies to disclose more financial information, often spurring them to go public.

The WSJ notes that “sources” say Facebook’s nowhere near the 500 mark.

What do you think? Is Facebook trying to control its valuation, keep more of its ownership close to its vest, or avoid the SEC?