Mixed signals breed mixed results, and today's sideways market reflects just that sort of environment.

With a paucity of concrete indicators, investors weighed positive auto, home, and retail sales against a bleak unemployment outlook and continued signs of slowing growth in Europe. This confluence of disparate signs ended with meager gains in the S&P 500 Index (^GSPC 0.02%), as it rose 0.3 points, or less than 0.1%, to close at 1,472. Nonetheless, three S&P 500 stocks stood out as laggards today. 

Organic Tex-Mex restaurant Chipotle Mexican Grill (CMG 0.40%), first and foremost, fell more than 5.5% today as it warned the markets about higher food costs that it expects will ding fourth-quarter earnings. Chipotle stock, which has seen a prodigious rise in the past few years amid rapid expansion and popularity, has gone through some tough times since hedge fund manager David Einhorn announced he was shorting the shares last year because of increasing competition. We'll have to wait until Feb. 5 to see how dramatically Chipotle results are affected by higher input costs. 

A week before, Allegheny Technologies (ATI 0.24%) is set to announce fourth-quarter results, its stock took a 4.3% hit. While there was no clear catalyst today, the selling may just have been a continuation of a year-long trend: Allegheny has lost 40% of its market cap in the last year. That, and investors in the steel and specialty metal producer were probably more than a bit underwhelmed with signs of a bleak European growth environment.

Shares in PC powerhouse Dell (DELL.DL) round out the last of the three big S&P losers Wednesday. Falling 4.3%, the stock was overdue for a correction, after rising 13% on Monday and 7% on top of that on Tuesday. Despite The Wall Street Journal's report that private equity group Silver Lake Partners was willing to offer as much as $13-$14 per share for the company, the level of uncertainty surrounding such a deal leaves shares trading around $12.60.