Social-networking giant Facebook's (NASDAQ:FB) earnings are always some of the most-watched in all of tech, and this week's earnings announcement didn't disappoint -- so much so that Facebook's stock both spiked and then crashed as much as 15% in after-hours trading as investors digested Facebook's quarterly results and listened in on its conference call.

Why such massive swings in both directions?

On the positive side, Facebook's key growth story remains every bit as robust as in past quarters. The company managed to grow its sales meaningfully, especially on the mobile front. Barring something short of a catastrophic event, Facebook's mobile advertising business is set to hit $1 billion in quarterly sales in the fourth quarter. Not bad for a segment of Facebook's business that didn't even exist two years ago. Investors should be very encouraged here.

Things got dicey, though, when Facebook CFO David Ebersman let a key detail slip that spooked investors big time.

So with so much conflicting evidence, how should investors frame Facebook's most recent quarterly performance? Fool tech and telecom analyst Andrew Tonner breaks down the numbers and what they mean for investors in the following video.

Fool contributor Andrew Tonner has no position in any stocks mentioned. The Motley Fool recommends and owns shares of Facebook. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.