Facebook's declining stock value hasn't just been bad for investors — it has also had a significant impact on the fortunes of Facebook employees.

Facebook employees have lost an average of $2 million each since the company went public in May, according to The Wall Street Journal, which cited new data from the compensation research firm Equilar. As of Friday, the average employee's stocks in the company were worth $2.5 million.

This average doesn't factor in executives at the company, some of whom lost much more. Sheryl Sandberg, the company's COO, has lost more than $700 million since the IPO. Meanwhile, Mark Zuckerberg, Facebook's co-founder and CEO, has lost an astounding $10.5 billion.

Facebook went public at $38 per share, but the stock quickly declined and went as low as $17.55 in early September. The stock has since rebounded slightly and closed Friday at just under $21, but it's still well below the IPO price.

To be sure, the average Facebook employee — like the company's executives — still has a handsome amount of money in Facebook stocks, but the larger problem is what this decline does to employee morale and talent retention. Many employees likely had dreams of selling the stock above the IPO price when the employee lockup periods expire at the end of this month. Instead, employees must either delay selling off their stock in the hopes that it rebounds, or else take a significantly lower payout — either of which may impact their personal plans.

Zuckerberg and other executives have begun to acknowledge the employee morale problem in public and in private, reportedly holding all-hands meetings to address employee concerns about the company's falling stock price. Facebook certainly isn't the only tech company whose stock price has fallen since the IPO — Groupon and Zynga have both seen their stocks collapse — but if Facebook's stock continues to sag, it could distract employees, make it harder to defend against poaching and more difficult for Facebook to acquire other companies.

What's more, there is still the question of whether and when the company's stock price will return to IPO levels. Barron's recently argued that the stock is overvalued even now and should be priced at $15 a share. Last month, Facebook's own underwriters Morgan Stanley and JP Morgan cut their 12-month price targets for the stock to well below the $38 IPO price. Doug Anmuth, an analyst with JP Morgan, now has a price target of $28 for the stock.

If that proves correct, it will be a long time before Facebook employees really see their fortunes improve.

Image courtesy of Flickr, Andrew Feinberg