Chipotle, which was decimated in the fourth quarter over a norovirus outbreak that followed an E. coli incident earlier in the fall, has parted ways with Edelman amid a conflict.

chipotleThe fast-food chain said in a Jan. 6 SEC filing that national media attention surrounding the norovirus incident in Massachusetts, along with the Centers for Disease Control and Prevention's ongoing probe of its earlier E. coli outbreaks, sparked a sales drop of 30% for the month of December.

The separation follows Edelman, along with CAA, and Chipotle's win of the PR Grand Prix award in Cannes in 2014 for "The Scarecrow" campaign.

Chipotle said it is currently considering agency proposals for PR as a new Edelman client conflicted with the relationship.

In the SEC filing, it also acknowledged a federal subpoena in a criminal probe related to an August 2015 norovirus incident at a Simi Valley, Calif., Chipotle restaurant.

The company said it will spend another $300M to repurchase shares, on top of $300M previously allocated. Its stock has plummeted from an August 2015 high of $758 to $416 today.