Chipotle just warned that its sales are tanking.
In a regulatory filing on Friday, the fast-food chain forecast that its comparable sales — at stores open for at least a year — will fall by between 8% and 11% in the fourth quarter.
The US Centers for Disease Control and Prevention (CDC) is investigating E. coli cases linked to Chipotle.
"Sales trends during the quarter so far have been extremely volatile," the company said in the filing. "Future sales trends may be significantly influenced by further developments, including potential additional announcements from federal and state health authorities."
Shares dropped by as much as 6% in after-hours trading.
Sales fell 20% in the days after it first closed 43 restaurants in Washington and Oregon on November 3, following the CDC's observations.
Those restaurants reopened a few days later, and sales recovered to about -9%.
But after the CDC announced four new E. coli cases linked to Chipotle, comparable sales fell by about 22%.
Earlier on Friday, the CDC said that seven more people had come down with E. coli, including cases in three new states: Illinois, Maryland, and Pennsylvania. And of the newest cases, one person reported eating at Chipotle a week before they fell ill.
The company said that it had "significantly increased" its efforts to ensure the safety of its food since the incidents were reported.
In the filing, Chipotle also said that its board had authorized share buybacks worth $300 million, in addition to previously announced repurchases totaling about $1 billion.
Screen Shot 2015 12 04 at 4.33.17 PMGoogleChipotle shares in after-hours trading on Friday.

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