Chipotle's new management still has the old problem: Food safety

Chipotle Mexican Grill's new CEO, Brian Niccol, is facing his first big test — a food safety outbreak.

The burrito chain briefly closed down one of its restaurants in Powell, Ohio, on Monday after a number of customers became sick. The restaurant reopened Tuesday.

While analysts have maintained their confidence in the brand, keeping outperform ratings and even upgrading the stock, it seems that investors remain queasy. On Tuesday, shares of the company were down more than 7 percent.

Chipotle told CNBC on Tuesday morning that the local health department received two illness complaints, but by Tuesday afternoon the Delaware General Health District reported receiving "over 100 calls and climbing."

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