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 hard-drive maker Western Digital (NYSE: WDC) fell off the Pacific continental shelf today, dropping as much as 11.1% on tremendous trading volume.

So what: The company is set to report first-quarter earnings after the closing bell today, and that event may very well move the stock further down or right back up depending on what we learn. This untimely drop comes from concerns that heavy flooding in Thailand will hurt this quarter's results.

Now what: This issue has hovered over Western Digital and archrival Seagate Technology (Nasdaq: STX) since early August, but it took a turn more recently as Western Digital issued a stern warning while Seagate appears to be chugging along quite nicely. Both companies report earnings this week, which will bring some clarity to the financial damages; there's even a small chance that the disaster could be good for margins, as tighter supplies might lead to higher prices. Knowledge is power, so I'd wait until Friday before diving into either one of these stocks.

Interested in more information about Western Digital? Add it to My Watchlist.

Fool contributor Anders Bylund holds no position in any of the companies discussed here. The Motley Fool owns shares of Western Digital. Try any of our Foolish newsletter services free for 30 days. We Fools don't 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.