Facebook (NASDAQ:FB) announced their second quarter earnings yesterday and their stock plunged more than 14% to a new low of $22.28 earlier this morning.  Their revenue was strong-than-expected and they continue to gain users, but it was not good enough for investors.

As of June 30th they are up to 955 million active monthly users (up 29% from last year) but their revenue growth has slowed.  Between 2009 and 2010, the company’s revenue nearly tripled.  In the first quarter of this year, revenue climbed 44%. In the second quarter, Facebook’s revenue increased 32% to $1.18 billion from $895 million a year earlier.  At the end of the first quarter, Facebook reported 901 million users.  It was stated on yesterday’s call that duplicate accounts were “more than expected.”

Overall they posted a loss of $157 million, or 8 cents per share in the April-June period, mainly due to compensation expenses it incurred when it paid $1.3 billion in restricted stock and related taxes for employees are part of the IPO.  The loss compared with earnings of $240 million, or 11 cents per share, in the second quarter a year ago. The company’s adjusted earnings of $295 million, or 12 cents per share.

Facebook CEO Mark Zuckerberg said that the website’s mobile users are more active than those using the traditional web.

“On average mobile users are around 20% more likely to use Facebook on any given day,” he said. “So mobile not only gives us the potential to connect more people with our services and also gives us the ability to provide more value and more deeply engaging experience.”

Facebook’s advertising revenue of $992 million made up 84% of their earnings.  They did not break this down from what potion was from mobile advertising.  The remainder of their revenue is from payments and fees from games and other applications.