What happened

Shares of at-home-postage provider Stamps.com (NASDAQ:STMP) are up 27.3% as of 10:45 a.m. EDT.

So what

This being earnings season, you're probably guessing that Stamps.com stock's surge has something to do with an earnings report -- and you're right.

Wednesday evening, after close of trading on the Nasdaq, Stamps.com reported its fiscal Q2 2017 results. Earnings more than doubled to $1.71 per share on a sales increase of 38% year over year (to $116.1 million). Analysts had only been looking for $1.65 in profit per share (and probably only pro forma at that), with sales of just $99.2 million.

Naturally, investors were pleased with the beat.

A Christmas postcard with notation that it was delivered by Santa Claus's Reindeer.

Stamps.com posted an early Christmas present to investors on Wednesday. It arrived Thursday morning. Image source: Getty Images.

Now what

They should prepare themselves to continue being pleased. Factoring Q2's strong performance into its guidance, Stamps.com said it now expects to close out this year with GAAP profit anywhere from $5.15 to $6.07 per share, and sales of between $435 million and $460 million. The new numbers call for profits per share $0.37 higher than Stamps.com had previously expected. Sales are now looking to come in about $30 million ahead of previous estimates.

So what does this mean for the stock? After Thursday's bump, Stamps.com stock carries a market capitalization of roughly $3.3 billion and a share price just north of $196. At the midpoint of new guidance, Stamps.com stock sells for about 35 times earnings, which sounds very expensive.

In fact, it probably is very expensive if Stamps.com slows down to analysts' long-term expectation of 21% annualized earnings growth. Then again, these are the same analysts who were wrong about Stamps.com in Q2.

Stamps.com shareholders can only hope the analysts will keep being wrong in quarters to come.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.