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's happening: Shares of Yelp (NYSE:YELP) were down 21.2% as of 11 a.m. Thursday after the local business reviews specialist reported mixed first-quarter results the night before.

Quarterly revenue rose 55% year over year to $118.5 million, including a 51% increase in local advertising revenue to $98.6 million, an 11% decrease in brand advertising to $6.6 million, and a 254% pop in "other" revenue to $13.3 million. On that last item, keep in mind Yelp's recently acquired online food ordering company, Eat24, contributed $5 million in sales during the quarter. Local advertising accounts also grew 43% year over year to roughly 90,200.

Meanwhile, that translated to 92% growth in adjusted EBITDA to $16.3 million, and a narrowed net loss of $1.3 million, or $0.02 per share, compared to a net loss of $2.6 million, or $0.04 per share in the year-ago period. On an adjusted basis, Yelp's net income was $7.9 million, or $0.10 per share.

Analysts, on average, were anticipating much lower adjusted net income of $0.01 per share, but on higher revenue of $120 million.

Why it's happening: For the current quarter, Yelp expects revenue of $131 million to $134 million, or well below analysts' expectations for second-quarter sales of $138.4 million. For the full year, Yelp anticipates revenue of $574 million to $579 million, while Wall Street was modeling sales near the high end of that range.

But likely more influential in today's drop -- and similar to last quarter's solid report -- are concerns about slowing growth in Yelp's active user base. Average monthly unique visitors climbed 8% year over year to 143 million in Q1, versus a 30% increase in the year-ago period and a 13% year-over-year jump in the previous quarter.

Even so, remember Yelp is currently working hard to ultimately monetize its international site base, though management has previously noted it will take some time to reach great enough scale to effectively do so. In the end, while it doesn't feel good to absorb a near-term loss like this, from a long-term investor's viewpoint I don't believe today's results are as bad as the market makes them seem.