After the Centers for Disease Control yesterday stated that it was investigating a more recent E. coli outbreak linked to Chipotle Mexican Grill (CMG) - Get Report , a formerly bullish analyst JPMorgan downgraded the stock, saying that the worst may not be over in terms of sentiment and that estimates will need to bottom before he can recommend the stock again.

WHAT'S NEW: In an update, the CDC said yesterday that it is now investigating another, more recent outbreak of a different, rare DNA fingerprint of Shiga toxin-producing E. coli O26 linked to Chipotle. Five ill people have been identified in Kansas, North Dakota, and Oklahoma and all five reported eating at a Chipotle restaurant in the week before their illnesses started, said the regulator. "Because it is not known if these infections are related to the larger, previously reported outbreak of STEC O26 infections, these illnesses are not being included in the case count for that outbreak," the CDC noted. In response to reports of potentially new cases of E. coli linked to Chipotle, a company spokesperson stated that the company has indicated before that it expected that it may see additional cases and that it was confident that it "can achieve a level of food safety risk that is near zero" given the new initiatives it is undertaking.

GIVEN PAUSE: JPMorgan analyst John Ivankoe downgraded Chipotle to Neutral and cut his price target for shares to $555 from $630 after the CDC's update. The analyst, who views the CDC's "strong allusion" that these new cases are "probably unrelated" to the prior outbreak as "very surprising and disappointing," now believes the consensus forecasts for Chipotle's earnings in fiscal 2016 and 2017 are "far too high" given that the news flow shows the impact of the company's health issues continuing. "Even rational and informed consumers could potentially be given reason to pause when choosing Chipotle over the plethora of fast casual competition in the marketplace," Ivankoe told investors in his research note.

STILL LESS CONCERNED: William Blair analyst Sharon Zackfia, conversely, says she still expects Chipotle to emerge "largely unscathed" over the longer term from the E. coli incidents that have plagued it recently. Near-term earnings visibility is hampered, however, until media reports subside and better clarity is achieved on the cost of implementing the company's new food safety protocol, Zackfia tells investors. Still, she expects Chipotle's comps to bottom in the current quarter and keeps an Outperform rating on the stock.

WHAT'S NOTABLE: Maxim analyst Stephen Anderson released research notes on two companies he believes could benefit from the E. coli and norovirus outbreaks at Chipotle -- Panera Bread (PNRA) and Zoe's Kitchen (ZOES) .

PRICE ACTION: Chipotle shares slid over 3.5% yesterday to close at $521.71. Over the last three months, the Mexican restaurant operator's stock has dropped nearly 30%.

Reporting by Jason Keil.

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