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 mobile software specialist Smith Micro Software (Nasdaq: SMSI) are trading 10% lower today after plunging as much as 14.6% in early trading on massive volume.

So what: The company reaffirmed earlier guidance with sales and earnings midpoints well above the average analyst estimate. We're probably looking at overheated expectations here, as Smith Micro's shares closed yesterday at roughly double the six-month low set at the end of August.

Now what: It's easy to see why you'd be enthusiastic over Smith Micro, because its client list is a veritable who's-who of the wireless industry. Verizon (NYSE: VZ), AT&T (NYSE: T), and Clearwire (Nasdaq: CMWR) all depend on its QuickLink Mobile product to manage high-speed connectivity needs for their smartphones. But today's news reminds us that not even the red-hot smartphone sector can beat every expectation, every time -- there's a limit to growth rates in every market.

Interested in more info on Smith Micro Software? Add it to your watchlist.

Fool contributor Anders Bylund holds no position in any of the companies discussed here. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool is investors writing for investors.