Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of online review provider Yelp, Inc. (YELP -0.79%) surged 20% today after its quarterly results and outlook topped Wall Street expectations.

So what: The stock has skyrocketed over the past year on a string of better-than-expected quarters, and yesterday's Q4 results -- net loss narrowed to $2.1 million vs. $5.3 million in the year-ago period on a revenue surge of 72% -- coupled with upbeat guidance only reinforces that trend. In fact, monthly unique visitors surged 39% year over year to 120 million with about 53 million of them coming from mobile devices, giving analysts plenty of good vibes over Yelp's monetization prospects going forward.

Now what: Management now sees full-year 2014 revenue of $353 million-$358 million, nicely ahead of Wall Street's view of $347.8 million. "We enhanced the mobile experience, brought on thousands of new local business customers and completed the integration of Qype, which accelerated our European expansion," CEO Jeremy Stoppelman said of 2013. "Looking to 2014, we will continue our geographic expansion, add new products and programs for our community of writers and find even more ways to drive value to business owners." Of course, with the stock now up a staggering 300% over the past year and trading at a 20-plus price-to-sales ratio, much of that bullishness might already be baked into the price.