Monday morning (05 August 2013), shortly after markets had opened, Facebook's stock finally passed its IPO price for the first time since the company's initial public offering on May 18th of last year. The stock briefly traded above $38 before falling back down and closing at $36.80.
Following the over-hyped IPO and the ensuing nosedive of Facebook's stock price, it took the company more than 14 months of rebuilding trust for its stock price to get back to this level. After the stock had been dancing around the $25 mark for the past few months, it took a better-than-expected earnings report to catapult it back to its IPO price.
Facebook had reported a steep increase in mobile ad revenue last week, indicating that the company is on track to successfully deal with the ongoing shift to mobile usage. More than 70 percent of Facebook's users access the service via mobile devices and almost 20 percent do so exclusively. In mid-2012, Facebook had finally started serving ads to its mobile users, a move than can be considered the key to the company's recent performance on the stock market.
You will find more statistics at Statista.