The Centers for Disease Control and Prevention (CDC) has been investigating a recent E. coli outbreak linked to McDonald's (MCD) Quarter Pounders. Early findings have raised concerns about slivered onions and beef patties.

In a release titled "Always Putting Food Safety First," McDonald's Chief Supply Chain Officer of North America Cesar Piña confirmed that the Quarter Pounder has been removed from menus in the states affected, stating that other beef products on the fast-food chain menu's remain unaffected.

McDonald's stock sank by 10% in Tuesday's extended trading on this news and has moved nearly 6% lower in Wednesday's session.

"The near-term risk is for continued negative news cycle here around this E coli issue with more consumers getting sick," BTIG managing director and restaurant analyst Peter Saleh tells Catalysts. "To blunt this, if we start if we see this kind of end here where we don't see any more consumers getting sick and it comes out of the news cycle over the next week or so, I think that's probably the best case scenario for McDonald's."

Saleh compares this scenario with Chipotle's (CMG) own E. coli outbreaks from nearly a decade ago: "I think this is more contained and more neutralized than what we saw back in 2015 with Chipotle."

BTIG downgraded McDonald's from Buy to Neutral in February, and is maintaining this rating amid these headlines.

Soda and snack maker Coca-Cola (KO) reported third quarter earnings results on Wednesday. Catch Yahoo Finance's coverage of what McDonald's E. coli outbreak could mean for Coca-Cola going forward.

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This post was written by Luke Carberry Mogan.