Facebook posted strong stock results Wednesday. The internet giant's shares rose 19%. It seemed strong mobile ads earnings contributed much to this increase.

After-hours trading showed stocks rose more than US$30 per share. This was the first time the company reached this share price since January. However, this was still below the US$38 per share IPO price of May 2012.

The main factor that contributed to the current stock performance was FB's mobile ad business. Mobile continues to take a big portion of FB's advertising business, as more and more people are using FB on their mobile phone and tablets. The company noted a year-over-year increase of 51% to 819 million.

As a result, FB saw an increase in its mobile ad sales. Out of its total ad revenue, 41% came from mobile ad sales, compared to only 30% last quarter.

"When it comes to mobile, I'm very pleased with our results," CEO Mark Zuckerberg said on a conference call with investors.