Sizing up Chipotle

• Chipotle (NYSE:CMG) is upgraded by JPMorgan to an Overweight rating from Neutral.
• Oppenheimer thinks investors should buy shares of the restaurant chain on any weakness.
• Last week, Chipotle reported sizzling comparable store sales growth in Q1, but also noted it was getting hit by higher food input costs.
• What to watch: An across-the-menu price increase from Chipotle is expected something this year.
• CMG +1.0% to $524.53 premarket