The One Reason Facebook’s Stock Just Skyrocketed

Facebook’s stock is up nearly 9% in after-hours trading Wednesday after the company’s first quarter results obliterated analysts’ expectations.

Facebook posted adjusted earnings of $.77 per share on revenue of roughly $5.38 billion for the quarter. Analysts expected earnings of $.62 per share and $5.26 billion in revenues, per CNBC.

How is Facebook making all that money? Advertising, mostly:

But it’s the source of most of that ad revenue that’s really impressive: mobile devices, like smartphones and tablets. Facebook’s revenue from mobile advertising represented a staggering 82% of the company’s $5.2 billion in total ad revenue this quarter, or about $4.3 billion.

That’s a big deal. People are increasingly spending time on mobile devices instead of desktop computers. Just over half of Facebook’s 1.65 billion monthly active users only visit the site on a mobile device. But mobile devices represent a big challenge for advertisers, as their smaller screens offer less room for ads. Facebook, with its in-feed ads, has clearly cracked the mobile nut.