The stock was off $15.46, or 3.3%, to $450.01 in late trading.
Several people reported feeling ill over the weekend and on Monday after eating at the restaurant in Powell, Ohio, near Columbus, Business Insider reported.
The company said it plans to re-open the restaurant on Tuesday, pending health department approval, according to the report.
Chipotle was one of Wall Street's high-flying darlings until 2015 when repeated food safety issues occurred, putting the stock into a tailspin that only appeared to end in February after nearly 66% of its value had been wiped out. The stock has posted substantial gains since bottoming at $247.52 earlier this year.