Chipotle Mexican Grill (NYSE:CMG) continued its blistering growth, as fourth quarter net income grew 47% on the strength of a 12.6% increase in same-store sales. The company said that despite rising input costs, it plans to hold the line on prices this year. The market sent the stock up more than 5% on the report.

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Growth Story Continues
Chipotle's excellent management continues to grow its earnings even faster than its fast-growing revenue, as it increases traffic and expands its number of restaurants. Chipotle pushed its operating margins up 140 basis points to 25.9% in the year-over-year quarter, and 180 basis points to 26.7% for the full year 2010 versus 2009. Although the company expects inflation for its beef and chicken ingredients to rise into the mid-single digits in 2011, it doesn't plan on initially passing these costs through to the consumer.

Burger Alternatives
There are a slew of chains along with Chipotle which operate beyond the burger model. Specialty sandwich restaurant Panera Bread (Nasdaq:PNRA) also turned in great fourth quarter earnings, with net income up 21.7%, revenue up 16.7% and same store sales up 5.2%. BJ's Restaurants (Nasdaq:BJRI) quadrupled its earnings, while Cheesecake Factory (Nasdaq:CAKE), though profitable, was hampered by poor weather. California Pizza Kitchen (Nasdaq:CPKI) also turned profitable after a loss in last year's same quarter.

As for Chipotle, one could argue Yum! Brands (NYSE:YUM) with Taco Bell paved the way for the wide cultural acceptance of burritos, a slipstream which Chipotle is riding to maximum advantage for its stunning success.

Turning Burritos into Cash
Chipotle's fourth quarter revenue rose 24.5%, and net income was $46.4 million or $1.47 per share, versus $31.6 million net income or 99 cents a share in the year ago quarter. Chipotle opened 62 new restaurants, with company plans to open 135-145 new restaurants in 2011. For the full year 2010, net income rose to $178.98 million or $5.64 a share, compared to $126.84 million or $3.95 a share, on revenue of $1.836 billion, up from $1.518 billion in 2009. Same store sales for the year increased 9%. These numbers read like a baseball superstar's stats - they're all great.

Chipotle's Prospects
There are a couple of other numbers to watch, however. The first will be food input costs. This was 31% of revenue in the fourth quarter, a slight rise from 30.1% in the previous year's quarter. Food inflation may end up making a larger impact on Chipotle than the company assumes.

Another number to watch is Chipotle's share price, which touched its 52-week high of $275. Investors might also want to look at the PE. Chipotle trades at a current PE just under 50 and a forward PE of 33, so investors are paying up for that impressive growth. Chipotle's a fast-food superstar right now, but the stiff premium in its stock price leaves an increasingly smaller margin of safety. (To learn more, see Sinking Your Teeth Into Restaurant Stocks.)

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