What: Shares of Sonic Corporation (NASDAQ:SONC) were down 11.3% as of 11:45 a.m. Tuesday after the restaurant chain announced in-line fiscal third-quarter 2015 results, but followed with weaker-than-expected guidance.

So what: Quarterly revenue rose 8.3% year over year to $164.7 million, helped by a combination of new restaurants and a systemwide same-store sales increase of 6.1%. That translated to a 15% increase in adjusted earnings to $19.3 million, and a 20% increase on a per-diluted share basis to $0.36. Analysts, on average, were anticipating roughly the same earnings on slightly lower revenue of $164.2 million.

For the full-year, however, Sonic now expects to achieve growth in earnings per share of 27% to 29%, or just below the roughly 30% growth anticipated by analysts on Wall Street.

In addition, Sonic says it expects to open 22 to 27 new franchises in the current fiscal fourth quarter, leaving it with a maximum of 47 new franchises opened for the entire fiscal year. By contrast, Sonic had previously set a goal of opening 50 to 60 new franchises this fiscal year. 

Now what:  That's not to say Sonic's results were bad. But Sonic stock isn't exactly cheap trading around 32 times trailing 12-month earnings and 24 times next year's estimates. Considering those estimates are likely to decline as analysts have time to digest today's guidance shortfall and slower than expected restaurant development, it's no surprise investors are taking a step back today.