Chipotle stock dropped after a CDC post about an E. coli outbreak listed three more states reporting people being infected by E. coli.
The fast-casual chain's stock closed down 12.5 percent. (Click here to track its shares.)
To date, the multi-state outbreak has affected 45 people in six states: California, Minnesota, New York, Ohio, Oregon, and Washington. Of this group, 43 ill people interviewed reported eating at a Chipotle in the week before their illnesses started.
"The epidemiologic evidence available at this time suggests that a common meal item or ingredient served at Chipotle Mexican Grill restaurants in several states is a likely source of this outbreak," the CDC stated.
In a Friday statement, Chipotle reiterated it continues to work closely with state and federal health officials.
"We take this incident very seriously because the safety of our food and wellbeing of our customers is always our highest priority," said Steve Ells, chairman and co-CEO of Chipotle. "We are committed to taking any and all necessary actions to make sure our food is as safe as possible, and we are working diligently with the health agencies."