Why this hot restaurant segment is plunging By: CNBC.com News August 15, 2014 at 12:12 PM EDT Fast casual is widely regarded as a bright spot in the ho-hum restaurant industry. Why then have some of the category's stocks cratered this year? Read More >> Related Stocks: Chipotle Mexican Grill Investment Technology Group Noodles & Company Piper Jaffray Companies Potbelly Corp