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 Western Refining (NYSE: WNR) fell as low as 12% in intraday trading Monday after RBC Capital cut its rating on the stock to "underperform" from "sector perform."

So what: While RBC also lifted its price target on the stock from $7 a share to $8 a share, it still represents a huge discount to where the stock is currently trading. And according to Thomson Reuters, even the average analyst one-year price target for Western Refining shares is $7.92 -- more than 20% below the stock's closing price on Friday.

Now what: Today's downgrade might provide the entry point that many investors have been waiting for. Driven by early success on several restructuring initiatives (paying down debt, refocusing portfolio, etc.), Western Refining shares have just about doubled over the past three months alone. The stock still trades at a forward P/E premium to the likes of Valero Energy (NYSE: VLO), Holly (NYSE: HOC), and ConocoPhillips (NYSE: COP), but if Western Refining continues to make turnaround progress, today's plunge might just be a short-term setback on the road to long-term multibagger gains.

Interested in more info on Western Refining? Add it to your watchlist.

Fool contributor Brian Pacampara owns no position in any of the companies mentioned. Try any of our Foolish newsletter services free for 30 days. 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 Fool's disclosure policy always gets a perfect score.