The shares of Chipotle Mexican Grill (CMG) are falling sharply after the company reportedly shut down one of its restaurants following complaints of customers who claim they got sick after eating there recently. Notably, the stock had been higher in early trading after research firm Maxim upgraded Chipotle to Buy from Hold, citingthe sales potential of its new Mexican cheese dip, which could be "an important catalyst" for the company in 2018.

VIRGINIA STORE CLOSURE: Chipotle has shut down a location in Sterling, Virginia, after eight reports were made to the website iwaspoisoned.com claiming that customers fell sick after eating there from July 14-15, according to Business Insider. The company's executive director of food safety, Jim Marsden, told Business Insider: "We are working with health authorities to understand what the cause may be and to resolve the situation as quickly as possible. The reported symptoms are consistent with norovirus. Norovirus does not come from our food supply, and it is safe to eat at Chipotle." 

QUESO CATALYST: The Mexican cheese dip, called queso, is currently being offered in a special Chipotle restaurant in New York City where new concepts are tested, wrote Maxim analyst Stephen Anderson. The product, which is more natural than "typical queso" offered by competitors, "found strong acceptance" at the New York location, said Anderson, who predicted that the product would raise Chipotle's margins next year and increase its same-restaurant sales by as much two percentage points. Anderson increased his 2018 EPS estimate for the company to $14.21 from $13.88, adding that the stock's 20% decline since mid-May and the upcoming queso launch have created a buying opportunity.

PRICE ACTION: In late morning trading, Chiopotle sank 4.4% to $374.64. Other restaurant shares have also moved lower as Chipotle has dipped, with McDonald's (MCD) and Starbucks (SBUX) each down about 0.6% and Wendy's (WEN) sliding about 0.7%.