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 fast-food restaurant franchiser Sonic Corp. (Nasdaq: SONC) made a tasty advance today, gaining nearly 13% after the company announced better-than-expected earnings.

So what: Fourth-quarter earnings season doesn't officially kick off until Alcoa's announcement next week, but there are still a smattering of companies not on the normal calendar schedule that are posting results this week. Sonic's fiscal first-quarter numbers topped Wall Street expectations, with revenue of $129.1 million and earnings per share of $0.12 besting the respective estimates of $128.8 million and $0.10. Same-store sales continued to decline, though at a slower rate of 2.4% versus 6.4% for the previous quarter.

Now what: Sonic's shares also benefitted from an analyst upgrade. Stifel Nicolaus' Steve West boosted the shares from sell to hold, saying that the company's fundamentals looked "less negative." West also suggested that value investors may be digging in in hopes of a continued turnaround. The directional momentum of the business, particularly in light of the company's continued ability to generate positive cash flow, could be a good reason to take a closer look at Sonic, particularly as investors bid up shares of competitors such as Chipotle (NYSE: CMG) and Yum! Brands (NYSE: YUM). However, management still has a lot of work ahead to get Sonic back on solid footing where it can start targeting growth.

Want to keep up to date on Sonic? Add it to your watchlist.

Chipotle Mexican Grill is a Motley Fool Rule Breakers choice and a Motley Fool Hidden Gems selection. The Fool owns shares of Chipotle Mexican Grill and Yum! Brands. 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.

Fool contributor Matt Koppenheffer does not own shares of any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or on his RSS feed. The Fool's disclosure policy is looking forward to a great 2011!