It took more than a year, but it looks like Facebook has finally impressed Wall Street.

Facebook's stock opened above $33 a share on Thursday, its highest opening price since the day after it went public last May, after smashing Wall Street's expectations with its second quarter earnings report.

The stock surged more than 30% overnight as Facebook beat earnings and revenue estimates for the quarter and, perhaps more importantly, came in well ahead of expectations for mobile growth, a key concern for investors. The number of monthly active users on mobile increased 51% year-over-year to 819 million. Mobile ads now account for 41% of Facebook's total revenue, up from essentially nothing a little more than a year ago and beating estimates that it would be about 33% of total revenue for the quarter.

"This quarter helps cement the bull thesis and underscores how successful FB's transition to mobile has been," Arvind Bhatia, an analyst with Sterne Agee, wrote in an investor note Thursday. "Over the long term, advertising dollars always seem to follow eyeballs and FB has plenty of eyeballs."

Facebook briefly traded above $32 a share in January after having plummeted to as low as $17.55 — half its IPO price — a few months earlier. Facebook went public at $38 a share, but has never traded at or above that mark after its first day on the public market.

The surge in stock price added $15 billion to Facebook's market cap overnight: It closed Wednesday with a market cap of about $64 billion and opened with a market cap of more than $80 billion.

For those keeping track, it also added a pretty penny to CEO Mark Zuckerberg's personal net worth. Zuckerberg's total Facebook shares — 609.5 million as of a filing with the SEC on March 31 — were worth about $16.2 billion on Wednesday. As of Thursday morning, those shares are now worth more than $20 billion.

To put that another way, Mark Zuckerberg's net worth increased by around $4 billion overnight.

FB data by YCharts

Image: Kevork Djansezian/Getty