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 off-road-vehicles builder Polaris Industries (NYSE: PII) went way off the beaten path today, sinking 11% deep in market sludge on heavy trading volumes.

So what: Polaris beat analyst estimates in last night's third-quarter earnings report and raised full-year guidance figures -- but the higher projections add up to a significantly weaker fourth quarter than had been expected once you factor in the size of this quarter's positive surprise. So this is a case of too much good news, too early, and no follow-through.

Now what: The company competes chiefly with Arctic Cat (Nasdaq: ACAT) and Harley-Davidson (NYSE: HOG), and the Hogfather's own gloomy report yesterday didn't help any. That said, don't cry for Polaris shareholders. The stock has crushed the market over the last year, or three, or 10, all while showering investors in healthy dividends. I think it's safe to see this drop as a rare buy-in opportunity, because one potentially weak quarter will soon be forgotten while rock-solid margins and growth trends live on.

Interested in more information about Polaris Industries? Add it to My 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. You can check out Anders' holdings and a concise bio, follow him on Twitter or Google+, or peruse our Foolish disclosure policy.