<p>Facebook founder and CEO Mark Zuckerberg.(Photo: Kimihiro Hoshino, AFP/Getty Images)Story HighlightsFacebook hit with the fourth unlocking of shares due to lockup expirationMore than 156 million shares are now able to be soldInvestors seem increasingly disinterested in Facebook's lockups as time wears on</p><p>Facebook stock finished 5% lower Friday as a fourth lockup expired, making more shares available for trading.</p><p>The shares closed at $26.81, down $1.43 or 5.06%.</p><p>At under $27 a share, the fear is that the sell-off of Facebook (FB) shares could worsen. And despite a rally in recent weeks, the stock remains below its $38 a share IPO price.</p><p><a href="http://www.usatoday.com/story/money/business/2012/12/14/facebook-ipo-lockup-expiration/1769295/">Keep reading...</a></p><p>Read also:</p><p><a href="http://www.searchenginejournal.com/nasdaq-100-facebook/56548/">Nasdaq 100&#039;s Latest Star: Facebook</a> (Search Engine Journal)</p><p><a href="http://www.businessweek.com/ap/2012-12-14/facebook-falls-as-lock-up-expires">Facebook falls as lock-up expires</a> (Businessweek)</p><p><a href="http://www.canadianbusiness.com/list-and-rankings/facebook-ipo-big-loser-2012/">Big Loser: Facebook Value down 28% since IPO.</a> (CanadianBusiness.com)</p><p>Explore: <a href="http://news.google.com/news/more?ncl=dtYhEgLXRYOIkuMshw8sL63pauVMM&ned=us">11 additional articles.</a></p>